JANUARY 31, 1978

THE

NAUTILUS

Vol. 92

No. 1

A quarterly

devoted to

malacology and

the interests of

conchologists

Founded 1889 by Henry A. Pilsbry. Continued by H. Burrington Baker.

Editor-in-Chief: R. Tucker Abbott

EDITORIAL COMMITTEE

CONSULTING EDITORS

Dr. Arthur H. Clarke, Jr.

Division of Moliusks

National Museum of Natural History

Washington. D. C. 20560

Dr. WUliam J. Clench

Curator Emeritus

Museum of Comparative Zoology

Cambridge, Mass, 02138

Dr. William K. Emerson

Department of Living Invertebrates

The American Museum of Natural History

New York, New York 10024

Mr. Morris K. Jacobson

Department of Living Invertebrates

The American Museum of Natural History

New York, New York 10024

Dr. Aurele La Rocque

Department of Geology

The Ohio State University

Columbus, Ohio 43210

Dr. James H. McLean

Los Angeles County Museum of Natural History

900 Exposition Boulevard

Los Angeles, California 90007

Dr. Arthur S. Merrill

Woods Hole Biological Laboratory

National Marine Fisheries Service

Woods Hole, Massachusetts ()'2543

Dr. Donald R. Moore

Division of Marine Geology

School of Marine and Atmospheric Science

10 Rickenbacker Causeway

Miami, Florida 33149

Dr. Joseph Rosewater

Division of Moliusks

U. S. National Museum

Washington, D.C. 20560

Dr. G. Alan Solem

Department of Invertebrates

Field Museum of Natural History

Chicago, Illinois 60605

Dr. David H. Stansbery

Museum of Zoology

The Ohio State University

Columbus, Ohio 43210

Dr. Ruth D. Turner

Department of Moliusks

Museum of Comparative Zoology

Cambridge, Mass. 02138

Dr. Gilbert L. Voss

Division of Biology

School of Marine and Atmospheric Science

10 Rickenbacker Causeway

Miami, Florida 33149

Dr. Charles B. Wurtz

3220 Penn Street

Philadelphia, Pennsylvania 19129

EDITOR-IN-CHIEF

Dr. R. Tucker Abbott

American Malacologists, Inc.

Box 4208, Greenville. Delaware 19807

Mrs. Horace B. Baker

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Subscription Price: $8.00 (see inside back cover)

THE

NAUTILUS

Volume 92, Number 1 — January 31, 1978

CONTENTS

A. M. Cvancara and P. G. Freeman

Diversity and Distribution of Mussels (Bivalvia: Unionacea) in a Eutrophic Reservoir,

Lake Ashtabula, North Dakota 1

Richard S. Houbrick

Redescription of (Bittium pmteum) (Jousseaume, 1930)

with Comments on its Generic Placement 9

Richard W. Fullington and Kate E. Fullington

A New Species ofAshmunella (Pulmonata: Polygyridae) from the Davis Mountains, Texas 12

Emile A. Malek and Rebecca R. Malek

Potential Biological Control of Schistosomiasis Intermediate Hosts by Helisome Snails 15

W. L. Pratt, Jr.

Nesovitrea suzannae A'Ne-w Zonitid Land Snail from Coastal Southern Texas 19

Mary Ann Gilbert

Aspects of the Reproductive Cycle in Macoma halthica (Bivalvia) 21

G, L. Mackie

E^ffects of Pollutants on Natality of M?iscw^mmsecwns (Bivalvia: Pisidiidae) 25

Arthur S. Merrill, Robert C. Bullock and David R. Franz

Range Extension of Mollusks from the Middle Atlantic Bight 34

Fred G. Thompson

A New Genus of Operculate Land Snails from Hispaniola

with Comments on the Status of Family Annulariidae 41

Morris K. Jacobson

Tarebia (Prosobranchia: Thiaridae) in Cuba 54

Beatrice L. Burch

Asian Clam, Corbicula, Threatens Hawaii 54

Dee S. Dundee and E. A. Cancienne

Louisiana Citrus Being Damaged by Snails 55

James A. Kushlan

Predation on Apple Snail Eggs (Pomacea) 57

Publications Received ii

STATEMENT OF OWNERSHIP. MANAGEMENT AND CIR-

CULATION (Required by) Act of October 23. 1962: Section

4396 Title 39. United States Code, and postal regulation

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1 Title of publication: THE NAUTILUS.

2 Dateof filing, September 25. 1977.

3. Frequency of Issue: Quarterly (4 per year),

4. Location of known office of publication: 429B Arthur

Drive, Hockessin, DE 19707,

5 Location of ttie Headquarters of General Business

Offices of the Publishers: 429B Arthur Drive,

Hockessin, DE 19707

6. Names and addresses of publisher, editor, and

managing editor: Publisher, American Malacologists,

Inc , PO. Box 420a Greenville, DE 19807 Editor, R.

Tucker Abbott. P.O. Box 4208. Greenville. DE 19807

Business Manager. Mrs Horace Burrmgton Baker. 11

Chelten Rd,. Havertown, PA 19083.

7. Owner: American Malacologists, Inc. P.O. Box 4208.

Greenville. DE 19807. R, Tucker Abbott.

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holders owning or holding 1 percent or more of total

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Extent and Nature of Circulation:

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copies Printed (Net

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I certify that the statements made by me above are cor-

rect and complete,

(signed) R. Tucker Abbott. Editor

PUBLICATIONS RECEIVED

Kay, E. Alison and William Magruder. 1977. The BioUigii of

Opihi [Patellidae: Cpllana]. 4(5 pp. Dept. Planning and

Economic Development, Honolulu. Hawaii, Significant study

of popular f(K)d limpets of Hawaii.

Ciolikov. A. N. and 0. A. Scarlato. 1977. Biocoenoses of the

Shelf of Franz Josef Land and the Fauna of Adjacent

Waters. Kxpl. Fauna Seas XIV, pp. 313-390. 1(M species

reported upon. New genus Arctimia (Ri.ssoidae): type:

Rismmjanmayeni Friele.

Boss, Kenneth .J. 1977. Monograph of larca (Bivalvia:

Semelidae). Ofnixiarinl Papirx on Molluxlcx. vol. 4. no. .57, pp

189-22.5. An excellent, well-illustrated revision of this Indo-

Paci fie subgenus of A bra.

.Johnson. Richard 1. 1977. Norman Macdowell Grier. a

Bibliography of His Work on Mollusks, with a Catiilogue of

His Unionid Taxa. lor. cit.. pp. 226-227. $2,00 for above two

papers,

Johnson, Richard I, 1977. Monograph of the Genus Medionidnx

(Bivalvia: Unionidae) mostly from the Apalachicolan

Region. Southeastern United States, lor. rit.. no. .5fi. pp.

I(il-1K7. illus,. maps. The taxonomy and zoogeography of six

species of freshwater mussels are thoroughly treated. .fl.-IO.

John.son, Richard I. 1977. Arnold Edward Ortmann. a

Bibliography of his Work on Mollusks, with a Catalogue of

his Recent Molluscan Taxa. lor. rit.. no. 58, p. 229-341. por-

trait.

Johnson, Richard I. 1977. The Carnegie Museum, its Collec-

tions and Curators of Mollusks. lor. rit.. pp. 242-214. 80 cents

for above tw<i.

Lyons, William G. 1977. (^bmments on Three Jamaican

Melanellid Species Described by C. B. Adams, loc. cit.. no.

.5.5, pp. 149-1,57.

Hornblower, Harriet. 1977. Alcide d'Orbigny's South

American E.xpedition (182(^183;3). loc. rit.. pp. 1.58-160. 60

cents for above two. All obtainable from the Museum of

Comparative Zoology, Cambridge, M.A 02138.

Solem, Alan. 1976. Enrhthmtoid Land Snaik from Pacific

hlaridif. Part 1. Family End(Klontidae. xii — .508 pp.. 206 pis.

$:35.fKl. Field Museum of Natural History, Chicago. This

magnificent work will take its place among the land

mollusca classics. These exquisite little snails, many of

which brood eggs in the umbilicus of the shell, have been

exhau.stively studied. Patterns of morphological variation

(both soft parts and shells), the phylogeny. ecology,

zoogeography, and systematics of the family are thoroughly

documented and beautifully illustrated. Independent trends

in the development of brood compartments is revealed

anmng the 185 endodontids. A total of 102 species and 19

genera are described as new. In any index of molluscan

genera the author will now come first and last, since he has

proposed the names .Aandonta and Zyzzijidonta. A valuable

geographical index is also included. Tribute is given to C.

Montague Cooke who left behind a preliminary manuscript

and the,se magnificent collections. (R. T. .Abbott).

Walls, Jerry G. Nov. 1977. Two New Cones from the We.stern

Pacific, lite Pariali P.O. Box 42. Hightstown, NJ (H520), no.

1, pp. 1-3, 4 figs. Conus uittigi from Timor and Tonus

tribhlri from off Taiwan are described as new. Privately

published by the author, .50 cents.

Vol. 92 (1)

January 31, 1978

TTie Nautilus 1

DIVERSITY AND DISTRIBUTION OF MUSSELS

(BIVALVIA: UNIONACEA)

IN A EUTROPHIC RESERVOIR,

LAKE ASHTABULA, NORTH DAKOTA

A. M. Cvancara

Department of Geology

University of North Dakota,

Grand Forks,

North Dakota .58202

and

P. G. Freeman

314 Belmont Road,

Grand Forks,

North Dakota 58201

ABSTRACT

Lake Ashtabula, a 28-year-old eutrophic reservoir on the Sheyenne River in

southeastern North Dakota, was surveyed for mussels by saiba diving during the

summer of 197 U. Belt transects, 20 m by 1.75 m and paralleling depth contours,

were run at six stations at each meter depth, usually to 6 m. Four species, in order

of decreasing abundance, were found in the lake: Anodonta grandis Say, Lampsilis

radiata (Gmelin), Amblema plicata (Say), and Lasmigona complanata (Barnes).

Eight species are known in the river above the lake and 11 species below the lake.

Lake individuals of A. grandis were conspicuously smaller than those in the river;

most (82.7%) had about two or three unnter rings, and the largest had about five.

Individuals of L. radiata, however, were of a size about normal for those in the

river: the largest individual had about seven winter rings. Most mussel individuals

occiured at 3 m (^6.9%) and 2 m (25.0%) fewest (3.1%) occurred at 6 m, and none

was found at 5 m. The maximum density was O.lfS individuals/m^ for A. grandis at

3 m. Individuals of A. grandis (collectively from all depths) decreased in numbers

down the reserimr toward the dam. The average density (from 2 and 3 m) of A.

grandis in the lake (0.27 individuals/ m^) was significantly (P=0.10) greater than

that in the river below the lake (0.05 individuals/m^) and about the same as that

above the lake (0.32 individuals/m^). The average density o/L. radiata in the lake

(0.05 individiwils/m^ ) was significantly (P = 0.10) less than that above the lake (0.'2iin-

dividuals/m^) and about the same as that below the lake (0.07 individuals/m^).

Pos.^ible causes for fewer mussel species in Lake Ashtabula are alteration of nor-

mal mussel reproductive processes and periodic low levels of oxygen content.

INTRODUCTION

It is well-known that the impounding of rivers

generally has adverse effects on the mussel

(Bivalvia: Unionacea) fauna of a natural

drainage, but the reasons are not always clear

(for summary of effects, see Fuller, 1974:

247-250). This paper reports the results of a study

of mussels in a 28-year-old eutrophic reservoir on

the Sheyenne River in southeastern North

Dakota.

Cvancara et al. (1976) have recently sum-

marized the mollusks in the Sheyenne River and

Lake Ashtabula and reported only two mussels,

from one station (fig. 1, station 6), in the lake.

Peterka (1972) analyzed the concentrations and

depth -occurrences of four snail and two pill clam

(Sphaeriidae) genera in Lake Ashtabula and said

(written communication, May 2, 1974) that five

young "Anodontidae" were collected (by Ekman

dredge) from 2-4 m at the mouth of Baldhill

Creek (station 4, fig. 1) and at 2.1 km above the

dam in July and August, 1966.

The Nautilus

January 31. 197H

Vol. 92 (1)

A

COLLECTING STATION

10 KILOMETERS

47°00 -

FIG. 1. Map of Lake AKhtahuta and vicinity showing wussel

collecting stations.

The generally north -trending Lake Ashtabula

(fig. 1) is backed up by Baldhill Dam (NW 1/4

sec. 18, T. 141 N., R. 58 W. 47° 02' N., 98°05'

W.), 8.4 km northwest of Valley City in Barnes

County, North Dakota. The reservoir occupies the

Sheyenne River Valley, whose floor is about 656

m below the .surrounding terrain at the dam. Oc-

cupying a glacial meltwater trench (Aronow,

1963), the valley is cut into late Quaternary

bouldery sand, silt, and clay (glacial till), sand

and gravel (glacial meltwater deposits), and silty

clay (glacial lake sediment) and Late Cretaceous

shales (Kelly and Block, 1967; Merritt, 1966). The

major tributary of the valley at the reservoir is

Baldhill Creek (fig. 1). The bottom sediment of

the reservoir is generally soft, organic mud

beyond a depth of 1-3 m (Table 1).

Peterka (1972), Peterka and Knutson (1970),

and Peterka and Reid (1969) have described the

physical, chemical, and biological characteristics

of I^ke Ashtabula. The reservoir began storage

in July, 1949; it is 43.5 km long at normal full

I>iol and up to 0.97 km wide. The maximum

depth, in the old river channel, is slightly over 15

m, and the mean depth is 4.0 m. At normal full-

pool elevation the surface area is 2197.5 ha and

the storage capacity is 8720.7 ha-m.

The water generally did not stratify (physical

and chemical measurements from April 1966 to

April 1967 unless otherwise stated (during ice-

free periods. Dissolved oxygen concentration was

6.4-13.9 mg/1 during ice-free periods (at a single

station) and nearly uniform throughout the water

column. Supersaturated o.xygen levels occurred

often during April through September, 1966. Dur-

ing ice cover, oxygen concentrations dropped to

lows of 8.2 mg/1 at the surface and 0.4 mg/1 at

the bottom. Secchi disc transparency (at a single

station) was 0.5-3.8 m, affected by both suspended

sediment and phytoplankton. Transparency in-

creased down -reservoir, was generally less than 1

m near station 2 (fig. 1), and averaged 2 m near

the dam; this generally agrees with the results of

Johnson et al. (1974; 16-17), obtained in July and

August, 1974.

Total dissolved solids (at a single station) have

varied from a little more than 200 mg/1 (April)

to more than 600 mg/1 (February) (Peterka and

Reid. 1969: fig. 5). Total alkalinity ranged from

140-160 mg/1 (April-May 1966) at all depths

to 330 and 440 mg/1 (April 1967) at the surface

and bottom. The pH values were 7.5-8.3 in April-

May 1966, 8.8-9.2 in June 1966-January 1967,

and decreased to about 8.0 in March-April 1967.

Generally, fluctuations of sulfate, ammonia,

nitrite, nitrate and total phosphate were similar

to those of dissolved solids and alkalinity; low

concentrations followed spring run-off and higher

concentrations were reached just before ice

break-up. The mean concentrations of total iron,

total and ortho phosphate, and bicarbonate

alkalinity (June 1967 to July 1968) were

significantly less in the lower and middle reaches

of the reservoir than in the upper part (Peterka

and Knutson, 1970; 19). Conversely, the mean

Vol. 92 (1)

January 31. 1978

The Nautilus 3

TABLE 1. Estimated predominant bottom sediment and percentage of rooted aquatic plant cover for six stations in Lake

Ashtabula in 1974 (stations are shown in fig. 1).

"Estimate of bottom sediment made by generally following percentage limits of Shepard (1954).

concentrations of nitrate nitrogen and carbonate

alkalinity were higher in the middle and upper

reaches of the reservoir.

Lake Ashtabula is highly productive with an

average annual gross primary productivity of 4.1

and 6.8 g O^/mVday for 1967 and 1968. Heavy

algal bl(X)ms occurred during the summer and

autumn of 1967 and 1968 when Aphanizomenon

hohaticum comprised about 90% of the blooms in

numbers and volume (Peterka and Knutson, 1970:

59, 62-63). A band of submergent vegetation, largely

of species of Potamogetoru occurred along the

shores of the reservoir in water 0.6-2.5 m deep

(Peterka and Knutson, 1970: 67). The existence of

this vegetation band is partly reflected in Table

1. The total zooplankton dry weight standing crop

was dominated by Daphnia, comprising 84% of

the standing crop in 1967 and 81% in 1968; the

average dry weight standing crop for D. pulex

was 1110 mg/m^ in 1967 and 2851 mg/m^ in 1968

(Peterka and Knutson, 1970: 25, 28). The average

standing crop of benthic invertebrates (spring

and summer of 1967; single station 3.2 km north

of the dam, fig. 1) was 7.2 g/m' and 2126 in-

dividuals. The total biomass consisted of mollusks

(snails and pill clams), dipterans, annelids,

ephemeropterans, and others (e.g., amphipods), in

order of relative abundance. Most (90% by

weight) of the invertebrates occurred at depths of

0-8 m (Peterka, 1972).

MATERIALS AND METHODS

During the summer of 1974, mussels were

surveyed at six stations in Lake Ashtabula by

scuba diving. The stations (fig. 1) were chosen so

as to be distributed over most of the lake, be

about equally spaced, and be in relatively un-

disturbed areas. No sampling was done above sta-

tion 1 because Lake Ashtabula above this point is

very shallow and largely a marsh. Belt transects,

20 m by 1.75 m and paralleling depth contours,

were run at each meter depth to 6 m, except at

station 1 where the maximum depth was less

than 5 m. The transects were limited to 6 m

4 "Hie Nautilus

January 31, 1978

Vol. 92 (1)

because of extremely low lateral visibility;

estimated values of visibility at 6 m for four sta

tions were 0-0.4 m. (At 3 m, the estimated values

at four stations were O.fi-1 m). To gain access to

the 6-m depth, it was usually necessarj' to locate

the former river channel; this was accomplished

by use of a Lowrance Electronics Mfg. Corp.

Fish-Lo-K-Tor. Each transect line was begun

from a bearing normal to shore, established with

an underwater compass. The transect line, a

nylon cord 5 mm in diameter with lead weights,

was held by a diver at one end while the other

diver e.xtended it along the desired depth contour

by means of an underwater depth gauge. All

mussels (alive and empty shells) that could be

reached on either side of the transect line (a

1.75-m-wide belt or band) were placed in a

numbered bag. Collecting was commonly done

strictly by feel because of the generally low

visibility. Observations on the estimated predomi-

nant bottom sediment and percentage of aquatic

plant cover were made for each transect. More

than 20 underwater manhours were devoted to this

survey.

Shells were measured (to the nearest milli-

meter) for length (greatest distance parallel to

the hinge line), height (greatest dorsoventral

distance normal to the hinge line), width (greatest

distance across both valves normal to a plane pass-

ing between them), and posterior length (greatest

distance parallel to the hinge line from the beak

to the posterior margin) in the field by use of a

specially contructed measuring box with a sliding

guide and by vernier calipers. The total weight

(body and shell) and shell weight were measured

to the nearest tenth of a gram. All excess mois-

ture w'as removed before weighing live individu-

als, and shells were dried before weighing.

Specimens used are encompassed within accession

numbers A 1203-1222 of the Department of Geol-

og>'. University of North Dakota.

RESULTS

Four mussel species, in order of decreasing

abundance, were found living in Lake Ashtabula

(Table 2): Anodonta grandis Say, Iximpsilis

rndiata (Gmelin), Amblemn plicnta (Say), and

Lasmigona complanata (Barnes). Individuals of ^.

grnndis were conspicuously small (Table 3); most

(82.7%) had about two or three winter rings and

the largest had about five. The ratios of posterior

length/length, total weight/length, and shell

weight/length of lake individuals of this species

were less than those of Sheyenne River in-

dividuals. Individuals of L. radiata were of a size

about normal for those in the river, and the

largest had about seven winter rings. The

male/female ratio of this species was 2. Too few

TABLE 2 Individuals of four species of mussels recovered from six stations in Lake Ashtabula.

•Each entry represents the individuals (empty shells indicated by parentheses) collected from a 20-m by L7.5-m transect. NS

= not sampled because the maximum depth was less than .5 m.

Vol. 92 (1)

January 31,1978

The Nautilus 5

TABLE :!. Statistical data of shell measurements, shell measurement ratios, weights, and weipht length ratios for Ariodonta

<iraii(ii.s Say and Liunpsili.s rddiata (Gmelin) from si.\ stations in Lake A.shtabula and 21 stations from the Sheyenne River above

and below the lake.

'River data were generated during the study of Cvancara et. al (1977).

'Only data for males are given.

lake individuals make comparisons with river in-

dividuals uncertain. The two individuals of A.

plicata were 81 and 100 mm, 62 and 78 mm, and

29 and -39 mm in length, height, and width, and

had about 4 and 7 winter rings. The single live L.

complanata was 80 mm, 65 mm, and 28 mm long,

high, and wide and had five winter rings.

Oviferous individuals were found of A. grandis

(stations 2 and 5 at 2-4 m; 20-21 August), L.

radiata (station 5 at 2 m; 20 August), and L.

complanata (station .5 at 2m; 20 August).

Most (71.9%) mussel individuals occurred at 3 m

(46.9%) and 2 m (25.0%), fewest (3.1%) at 6 m, and

none was found alive at 5 m. Empty shells common-

ly occurred in numbers comparable to those for live

individuals (Table 2). The maximum density was

0.43 individuals/m^ for .4. yrandis at 3 m. The

average densities (individuals/m^) for A. grandis

and L. radiata at combined 2- and 3-m depths were

0.27 and 0.05. Total A. grandis decreased

significantly (P<0.01) and linearly down the reser-

voir toward the dam (r = -0.96).

Densities of A. grandis and L. radiata in the lake

did not show a consistent pattern as compared with

densities in the river (Table 4). The average density

of A. grandis in the lake was significantly greater

than that in the river below the lake, but about the

same as that above the lake. The average density of

L. radiata was significantly less than that above

the lake, but about the same as that below the lake.

The relative abundances of the two species were

about the same above and below the lake, but

decidedly different in the lake.

B The Nautilus

January 31, 1978

Vol.92 (1)

TABLK t. Density of Anodonta grandis Say and Lampsilis radiata (Gmelin) in Lake .■\shtabula (from 2- and 3-m depths)

and Sheyenne River above (three stations) and below (four stations) the lake.

Km above or

below lake dam

A. grandis

Density (individuals/m'^)

L. radiata

250.0

150.6

58.2

30.6

23.6

20.1

14.2

8.0

0.5

3.0

111.3

274.8

399.4

Mean

r i-=0.32

NS

Mean

^=0.27

Mean

•=0.05

r 0.143-1

0.21

L 0.60 J

0.14a

0.21

0.60

0.54

0.51

0.34

0.20

0.03

I- 0.00 -J

0.01

0.14

0.00

0.05

NS

]

' Values are listed in downstream and downlake order. Lake values are underlined.

'S= compared means are significantly different (t-test; P = 0.10). NS = eompared means are not significantly different

(t -test ;P = 0.10).

TABLE 5. Comparison of mussel species in Lake Ashtabula with those in the Sheyenne River above and below the lake.

1. Amblema plicata (Say)

2. Fiisronaiaflavn (Rafinesque)

3. Quadrula quadnda (Rafinesque)'

4. Anodonta grandis (S&y)

5. Anoddntoideftferiisfinrinnus (Lea)

6. Ldsmigami complanata (Barnes)

7. L. compressa (Lea)

8. Stmiihitui^ ii)idulatu.'< (Say)

9. Latnpxilui nvata (Say)

10. L radiata (GmeVm)

11. Ligimiin recta (I.amarck)

12. Fniptrraalata (Say)

3

2

10

3

5

3

1

9

7

11

6

10

1

4

6

9

2

1

"Number of stations at which aspecies was found among totals of 6. 16. and 11 in the lake, above the lake, and below the lake.

'Data for the Sheyenne River are from Cvancara pt. nl. (1976).

'Only empty shells of this species were found, in the river below the lake.

Vol. 92 (1)

January 31, 1978

The Nautilus 7

DISCUSSION

Considerably fewer mussel species were found

in Lake Ashtabula than are known to exist in the

Sheyenne River above and below the lake (Table

5). Those found in the lake are the same species

as those found at most stations in the river. The

chances of finding additional species in the lake

can be estimated from the Poisson distribution,

which fits the observed species distribution

remarkably well. The Poisson probability of find-

ing more than four species is 0.003 based on an

extension of the observed data (Darnell, 1971:

189-193). One might ask, what would the mussel

fauna be like if Lake Ashtabula were elsewhere

on the Sheyenne River? If farther downstream,

more species might occur since diversity is

greater in the lower reaches of the river (Table

5). Other studies (summarized by Fuller, 1974:

247-250) have demonstrated the smaller number

of mussel species in reservoirs as compared to

those in the nonimpounded river. Shifts in the

species composition may also occur, with com-

monly increased prominence of members of the

Anodontinae. This was documented for reservoirs

on the Tennessee River (Bates, 1962; Isom, 1969,

1971). Baker (1928), in a dammed-up creek system

in Wisconsin, found that only two mussels out of

eight remained in the man-made lakes—Anodonta

grandis (including "Anodonta marginata") and

iMmpsilis radiata. A. grandis, an anodotine, was

the dominant mussel found in Lake Ashtabula,

followed by L. radiata (Table 2).

Possible causes for fewer mussel species in

Lake Ashtabula are 1) alteration of reproduc-

tive processes and 2) periodic low levels of ox-

ygen content. Since most mussels are dependent

on a fish host for dispersal and development of

the glochidial larva, fish species in Lake

Ashtabula were checked (from Farmer, 1974 and

from a list compiled by Dr. John B. Owen,

Department of Biology, University of North

Dakota and his students). Fuller (1974: 228-237)

has compiled a list of host fishes for many mussel

species from the literature. With the exception of

Anodontoides fe7nssacianns (Lea), all mussels in

the Sheyenne River with known fish hosts have

one or more host fishes present in Lake Ashtabula.

Therefore, there seems to be no problem with

glochidial host availability. However, even though

a suitable host is present, the level of infection by

glochidia in reservoirs may be very low. Also, the

reproductive process may be altered by loss of

glochidia in the soft substrate or by increased at-

tacks upon larvae by microorganisms, especially

under conditions of high siltation and organic

enrichment (summarized by Fuller, 1974: 222,

247, 252), as are present in Lake Ashtabula.

Periodic low levels of oxygen also may be

responsible for low mussel diversity in the lake.

Peterka and Reid (1969: 145) recorded a low of

0.4 mg/1 on the bottom (8 m) between stations 5

and 6 on 27 February 1967; Mr. James Ragan, of

the North Dakota Game and Fish Department,

reported (letter dated 4 August 1975) 0.5 mg/1 at

4.5 m depth at station 2 on 18 February 1970. The

preponderance of Anodonta grandis in the lake

suggests that this species is physiologically more

adaptable to conditions of marginal oxygen. Isom

(1971) attributed the sparse mussel fauna in Fort

Loudon Reservoir on the Tennessee River to

periodic insufficient oxygen resulting from

organic enrichment entering the upper reservoir.

Individuals of A. grandis were conspicuously

smaller in the lake than in the river (Table 3),

not because of stunting, but because the lake

forms were consistently younger, as mentioned

under Results. It is possible that the prepon-

derance of young individuals is due to

significantly low water causing a dying off prior

to their birth. The lowest levels (below normal res-

ervoir level) during 1969-1974 were 8.22 feet (early

April), 3.40 feet (early April), 4.34 feet (late

March), 3.90 feet (early March), 2.79 feet (early

March), and 8.49 feet (early April) (data from Mr.

Melvin Rieman, Flood Control Dam Operator for

the U.S. Army Corps of Engineers, 11 August

1975). The 8.22-foot drawdown in 1969 may be

significant because most individuals of A. grandis

were found at 2 and 3 m in 1974. and the time of

the drawdown is close to the estimated time of

birth of most of the individuals collected. Most of

the adults may have died during the drawdown,

and the shallow-water populations may have been

dominated thereafter by juveniles developed after

the water level rose. If reservoir level -lowering is

significant, however, it is unclear why Lampsilis

8 The Nautilus

January 31,1978

Vol. 92 (1)

radiata was not represented primarily by younp

individuals. Also, the possible detrimental effects

of the 8.49-foot drawdown in 1974 were not evi-

dent in either species.

The smaller posterior lenjrth/lenpth ratio of lake

individuals of A. grandis implies more centrally

placed beaks, but may be the result of generally

younger individuals in the lake than in the river.

Clarke (1973: 69, 80) found high values of the

anterior to beak length/length ratio (which cor-

respf)nd to low values of the posterior length/

length ratio) in individuals of A. grandly from

large lakes. He said such values imply a superior

development of the foot for maintaining position

better in lakes in exposed habitats and on shift-

ing substrates (of sand). This explanation is ques-

tionable since one might expect currents in

rivers, especially during flood stage, to affect a

mussel's position on the bottom as drastically as

does wave action.

The greatest concentration of individuals at 3

m differs notably from 1 m in Long Lake, a

natural lake in northwestern Minnesota.

However, the maximum density of 0.43 in-

dividuals/m^ is similar to the 54 mussels/m^ in

L<ing Lake (Cvancara, 1972: 155). The scarcity of

trees and long fetch at Lake Ashtabula are con-

ducive to frequent, strong wave action that may

result in more disturbance and fewer individuals

at depths less than 3 m.

The fewer individuals with increasing depth in

Lake Ashtabula also occurred in Long Lake. In

both lakes, this may be because of decreased

biological activity (slower metabolism, reproduc-

tion and growth) as related to lower

temperatures (Cvancara, 1972: 157). In Lake

Ashtabula, however, thermal stratification has

generally not been observed (1966-1967) during

ice-free periods, but does occur during such times

in Ijong Lake. It may be, too, that periodic low

levels of oxygen on the bottom result in fewer in-

dividuals with depth.

'Hie decrease in numbers of individuals of A.

grandit down the reservoir toward the dam may

be due to a chemical factor. As mentioned under

Introduction, total iron, total and ortho-

phosphate, and bicarbonate alkalinity were less in

the lower and middle reaches of the reservoir

whereas nitrate nitrogen and carbf)nate alkalini-

ty were higher in the middle and upper reaches.

It is unclear, however, which chemical factor

might be responsible and how it might relate to

mussel density.

ACKNOWLEDGEMENTS

J. P. Bluemle and M. E. Bluemle, North

Dakota Geological Survey and Department of

Geology, University of North Dakota, aided in

collecting river specimens of Anodonta grandis

and Lainps-ilis mdiatn used in making com-

parisons with those in the lake. A. C. Lindem, Jr.,

Manager of Academic Systems at the University

of North Dakota Computer Center, aided in the

tabulation and analysis of shell and weight

measurements. We wish to thank Mr. Samuel L.

H. Fuller for his rigorous review of our initial

manuscript.

LITERATURE CITED

Aronow, S. 1963. Late Plesitocene glacial drainage in the

Devils Lake region. North Dakota. .7imr. (Tpo/. 74: 8.59-874.

Baker, F. C. 1928, Influence of a changed environment in the

formation of new species and varieties. Ecotwui 9(3):

271-283.

Bates, J. M. 1%2. The impact of impoundment on the mussel

fauna of Kentucky Reservoir. Tennessee River. .4m. Midi

7Va(/. 68{1):2;&236.

Clarke. A. H,. Jr. 1973. The freshwater molluscs of the Cana-

dian Interior Basm. MalacoU)gia 13(1-2): 1-509.

Cvancara, A. M. 1972. Lake mussel distribution as determined

with SCUBA. &«/oyi/ 53(1): 1.54-1.57.

Cvancara, A. M.. J. P. Bluemle, and M. E. Bluemle. 1977.

Variation of shell dimensions and shell and total weights of

Anodonta grandis Say and Laniptsilit: mdiata ((imelin)

(Bivalvia: Unionidae), Sheyenne River. North Dakota. I^oc.

N. Dak. Acad. Sri. 29(11) (in press).

Cvancara, A. M.. R. D. Norby. and J. B. Van Alstine. 1976.

Mollusks of the Sheyenne River. North Dakota, U.S.A.: pre-

sent and past. Makicol. Rer. 9(1):25-:S.

Darnell. R. M. 1971. Organism and environment, a manual of

quantitative ecology. W. H. Freeman and Co., San Fran-

cisco. 290 p.

Farmer, P. .1. 1974. Age and growth, population structure, and

relative abundance of several fish species in Lake

Ashtabula, North Dakota. M. S. thesis. Univ. N. Dak. 107

pp.

Fuller, S. L. H. 1974. Chapter 8. Clams and mussels (Mollusca:

Bivalvia). Pages 215-273 in C. W. Hart, Jr. and S. L. H.

Fuller, eds. Pollution Ecology of Fresh uxiter Invertebraies.

Academic Press, N. Y. 416 pp.

Vol. 92 (1)

January 31, 1978

TTie Nautilus 9

Isom. B. B. 1969. TVie mussel resource of the Tennessee River.

Mnlncolmjm 7(2-3): :S7-12.5.

Isom. B. B. 1971. Mussel fauna found in Fort I/iudon Reser-

voir, Tennessee River, Knox County, Tennessee. Shdm-ul

Ker. 4: 127-130.

Johnson. G. E. et al. 1974. Environmental impact assessment

of BaldhiU Dam and Lake Ashtabula, North Dakota. Univ.

N. Dnk: Inst. End. Studies Res. Rep. No. 2. 206 p.

Kelly. T. E. and D. A. Block. 1967. Geology and ground water

resources Barnes County. North Dakota. Part I. Geology .V.

Dak: Geol. Sunvy Bull. 43. 51 pp.

Merritt. .J. C. 1966. Surfieial geology of the southern half of

Griggs County. North Dakota. M. S. thesis. Univ. of N. Dak.

78 p.

Peterka. J. J. 1972. Benthic invertebrates in Lake Ashtabula

resen-oir. North Dakota. /I ?«. Mull. Nat. 88(2): 408-418.

Peterka. J. J. and K. M. Knutson. 1970. Productivity of

phUoplankton and quantities of zooplankton and bottom

fauna in relation to water quality of Lake Ashtabula reser-

voir. North Dakota. Research Project Technical Campleticm

Report. N. Dak. Water Resources Res. Inst.. Fargo, N. Dak.

79 pp.

Peterka, .1. J. and L. A. Reid. 1969. Primary production and

chemical and physical characteristics of Lake Ashtabula

reservoir. North Dakota. Proc. N. Dak. Acad. Sci. 22:

l:«-1.56.

Shepard, F. P. 19.54. Nomenclature based on sand-silt ratios. J.

Sed. Petrology U{3): 151-158.

REDESCRIPTION OF BITTIUM PROTEUM

(JOUSSEAUME, 1930)

WITH COMMENTS ON

ITS GENERIC PLACEMENT

Richard S. Houbrick

Associate Curator, Dept. Invertebrate Zoolog>'

National Museum of National History

Smithsonian Institution

Washington. D. C. 20560

WTiile examining cerithiid-type-material from

the Museum d'Histoire Naturelle, Paris, I came

across five lots of specimens from Aden that were

described by Jousseaume in 1930 as Cerithium pro-

teum. All of the specimens are less than 5.2 mm in

length and have extremely variable sculpture that

consists of intersecting axial and sprial cords.

Jousseaume (1930) noted the conchological po-

lymorphism and remarked that each individual

could be construed as a separate species were it not

for the intergradation of forms within a popula-

tion. The type-shells have wide, shallow, short

anterior siphonal canals and very weak anal

sinuses that are indicative of the genus Bittium

Gray, 1847 rather than Cerithium Bruguiere, 1789.

To my knowledge, Cerithium proteum was not

mentioned again in the literature until 1971 when

Biggs examined a series of small cerithiids

collected in beach drift from the Dahlak Island,

Ethiopia, by the Polish Expedition to the Red Sea

("Dar Opola"). Biggs (1971) was unable to identify

the specimens or place them into any known genus;

consequently, he proposed the genus Dahlakia

which he suggested should be placed somewhere

near the potamidid genera Pirenella Gray, 1847

and Cerithidea Swainson, 1840. He described four

new species based on the material collected at the

Dahlak Islands: Dahlakia leilae (type-species of the

genus), D. striata, D. jugosa and D. pirenelloides. I

believe these four species are conspecific with

Cerithiimi proteum Jousseaume, 1930. Examina-

tion of Jousseaume's type-material, which consists

about 100 specimens, shows that all of the

characters used by Biggs (1971) to define his species

10 TTie Nautilus

January 31, 1978

Vol. 92 (1)

exist in C. proteum and intergrade with each other,

clearly indicating one extremely variable species.

Some of Jousseaume's specimens were collected

alive and still have their opercula and smooth pro-

toconchs in contrast to the beach-worn specimens

of Biggs. The operculum of C. proteum is thin,

corneous and paucispiral with an eccentric nucleus

characteristic of a cerithiid operculum. Biggs (1971)

was thus mistaken in referring his specimens to the

Potamididae.

Cerithium proteum seems to be a Bittium

species, but there is much confusion and

disagreement about the limits and subdivi-

sions of this group. Many small cerithiid

genera and subgenera are artificial groupings

that do not reflect sound phytogeny and are

impossible to use on a practical toxonomic

level. I have commented on the nomenclature

and usages of Bittium elsewhere (Houbrick,

1977) and suggest that Dahlakia Biggs, 1971

should be considered a synonym of Bittium Gray,

1847. A synonymy and redescription of Cerithium

proteum Jousseaume, follow:

SYNONYMY

Subfamily Cerithiinae Fleming, 1828

Genus Bittium Leach in Gray, 1847

Ritttiim 1847 (Oct.), I^ach in Gray, Annalti. Mag. Nat. Hist.

20:270. Type-species. Miirei retwulatiis Montagu, 180.3

=Stnimbif(innis retu-idnius Costa, 1778). by subsequent

designation. Gray, 1847 (Nov.), Proc. Zool. Sric. London

129:154.

FIGS, a - d, Bittium proteum (Jouxseaume, 19:10). Lectoti/pe (a)

and representative paratifiKf; frtm Djibmiti French Somaliland

(h-d) shou-ing variation in shell form and sculpture.

Meaxurements: a) 5.1, X Zi mm: h) 5.9 X 2.1, mm: c) i.9 X 2.:i

mm:d) ti.,1 X 2.x mtn.

Dnhlak-ia 1971, Biggs, Joum. Conch. 27:221. TVpe-species,

[hhlak'ia leilae Biggs. 1971 l—Cerithum proteum Jousseaume,

lOmt). by original designation.

Bittium proteum (Jousseaume)

(Figs, a- d)

1930 Cerithium proteum Jousseaume, Joum. de Conchyliol.

74: 28.3-284, fig. 1. Djeddah. Hf)deidah. .\den Djibouti

(type-locality here restricted Xx) Djibouti. French

Somaliland). Lectotype, Mus. Hist. Nat., Paris, not

registered. (.5.4 X 2.2mm)

1971 Dahlakia leilae Biggs, Joum. Conch. 27: 221. pi. 7. fig. 3.

Entedebir I., Dahlak Archipelago, Red Sea. Holotype:

Zool. Inst. Polish Acad. Sci., Warsaw.

1971 Dahlakia .'ttriata Biggs. Joum. Omch. 27: '22. pi. 7. fig. 1.

Entedebir I., Dahlak Archipelago, Red Sea. Holotype:

Zool. Inst. Polish Acad. Sci., Warsaw.

1971 Dahlakia .mgosa Biggs. Joum Conch. 27:^2, pi. 7, fig. 2

Ente<iebir I.. Dahlak .\rchipelago. Red Sea. Holotype:

Zool. In.st. Polish Acad. Sci., Warsaw.

1971 Dahlakia pirenelloides Biggs, Jounj. Conch. 27: 222, pi. 7.

fig. 4 Entedebir I., Dahlak Archipelago. Red Sea.

Holotype: Zool. Inst. Polish Acad. Sci. Warsaw.

RE-DESCRIPTION

Shell tiny (3.7-5.2 mm in length; 1.7-2.3 in

width), turrited, elongate, consisting of 7-9

moderately inflated whorls having an apical angle

of 28-45 degrees. Whorls sculptured with slanted

axial ribs, numerous thin spiral cords and striae of

variable number. Intersections of axial ribs and

spiral cords usually beaded. Whorls sometimes

lacking axial ribs sculpture and with reduced

sprial sculpture. Protoconch smooth, 2-2.5 whorls.

Suture deeply incised. Aperture ovate, columella

concave with slight callous. Outer lip convex, thin,

weakly crenulate. Anal canal very small. Anterior

siphonal canal short, broad and shallow, very

slightly reflexed backwards. Shell color tan to dark

brown, axial ribs usually flecked with white. Aper-

ture yellowish brown. Operculum thin, corneous,

tan, ovate, paucispiral with eccentric nucleus.

Radula and soft parts unknown.

REMARKS

As Jousseaume (19.30) remarked, this species is

exceedingly variable in sculpture and form (see

figs. a-d). Although Bittium proteum is

characterized by its inflated whorls and by slanting

axial ribs and riblets, some individuals are almost

devoid of sculpture and others are rather elongate.

Elongate individuals were named Dahlakia

Vol, 92 (1)

January 31, 1978

The Nautilus 11

pireneMoiden and D. leilae by Biggs (1971). Bittium

proteum is normally more stocky than B.

retlculatnm. the type-species of the genus, and is

closest in shape to several Tertiary sjjecies from

Venezuela described by Weisbord (1962) and refer-

red to a new subgenus, Brachijhittium Wesbord,

1962; Bittium caraboense. B. venezuelanum, B.

salirme. and B. palitoense. These fossil species are

also variable in sculpture and I question the tax-

onomic necessity of a new subgenus to accomodate

them because good supraspecific characters are, in

my opinion, lacking.

Jousseaume (1930) did not designate a holotype

and I have been unable to find a paratype that ex-

actly matches the figure given in his paper; thus, I

herein select a lectotype (fig. a, this paper, 5.4 X 2.2

mm) and restrict the type-locality to Djibouti,

French Somaliland.

Bittium proteum most likely occurs throughout

the Red Sea but may be overlooked by collectors

due to its small size. It is not well -represented in

American museum collections: The National

Museum of Natural History, Washington, D.C. has

only two lots, from Jidda, Saudi Arabia and Port

Sudan, Sudan. Bigg's material is from the Dahlak

Ids., Ethiopia and the original type-material of

Jousseaume was collected in French Somaliland

and Aden. Thus, Bittium proteum may have a

larger geographic distribution extending into the

Indian Ocean.

ACKNOWLEDGMENTS

I wish to thank Photographic Services of the

Smithsonian Institution for the photographs and

the Museum d'Histoire Naturelle, Paris for loan of

the types of Bittium proteum.

LITERATURE CITED

Biggs. H. E. J., 1971. On a proposed new genue of cerithid

mnllusca from the Dahlak Islands, Red Sea. Jour. Cnnch. 27:

221-22.3, pi. 7.

Bruguiere, J. G., 1789. Encyclopedie Methodique. Histoire

Naturelle des Vers. Paris. 1(1): 1-.344.

Costa. E. M. da, 1776. Elements of G/nchoioyy: or an introduc-

tion to the knowledge of shells. Ulust. London, viii -I- vi + .318

pp. 7 pis.

Fleming, J.. 1828. The philosophy of zoology or a general view of

the structure, functions and classifications of animals, etc.

Edinburgh. 2 vols.

Gray. J. E., 1847 (Sep.). The classification of the British mollusca

by N. E. Leach M.D. Annals. May. Nat Hist. 20:267-273.

Gray. J. E., 1847 (Nov.). A list of the genera of Recent mollusca.

their synonyma and types. Proc. Zool. Soc. London, part 15:

129-219.

Houbrick, Richard S.. 1977. Reevaluation and new description of

thegenusS!'»!wm (Cerithiidae). Veliger 20(2): 101-106.

Jousseaume, F., 1930. Cerithiidae de la Mer Rouge. Joum. de

Conch yliol 74: 270-296, 3 figs.

Montagu, George. 1803. Testaj^ea Britanmra. or natural history

of British sea shells, marine, land and freshwater, parts 1 and

2, 1803; i-,\.xxvii, -I- 606 pp.. .30 pis. (Suppl. 1810).

Swainson, William. 1840. .4 Treastise On Malacology, or shells

and shellfish. London, i-viii + 419 pp.

Wiesbord, Norman E., 1962. Late Cenozoic gastropods from

northern Venezuela. Bull Amer. Paleont. 17(193):7-672, 48

pis.

12 The Nautilus

Januarv 31. 1978

Vol. 92 (1)

A NEW SPH'IES OF ASHMUNELLA

(PULMONATA: POLYGYRIDAE)

FROM THE DAVIS MOUNTAINS, TEXAS

Richard W. Fullington

Invertebrate Department,

Dallas Museum of Natural History,

Dallas, Texas 75226

and

Kate E. Fullington

Department of Biolopy,

North Texas State University.

Denton, Texas 76201

ABSTRACT

Ashmunella sprouli FiillliKiton and Fullimitdn is the third sprrirs afthis (jemiR

descril)('(l fniiii the I kwi.'i Mountains. Jeff Ikivis Count n. Texas. The type loeality w

a localized colony in an igneous talus slide at)ore No. l<i Spring. Hell's Canyon, on

the R. E. Sproul Ranch.

Ash m u nelln sf)rouli

Fullington and F\illington, spec. nov.

(Figures 1 to 3)

Holotyp)e description - Shell light-brown, slight-

ly convex above (although 5 of the 41 collected

specimens were dorsally flattened or even con-

cave), and moderately umbilicate (umbilical

width, 3.41 mm; contained 3.4 X in shell

diameter). Whorls, 5 1/2, tightly coiled; suture

lines slightly indented. Periphery sharply

carinated and the last whorl is deflected

downward immediately behind the peristome.

The peristome thin and expanded, but not

flanged. Two parietal teeth; the upper is shorter,

more degenerate than the larger, s-shaped lower

parietal. The larger parietal tooth bends toward

the upper parietal at its upper end. The

peristome contains 3 palatal teeth. The upper-

most is elongate, and rests very obliquely across

the nearly converging parietals. Basaily, two

laterally compressed teeth are connected by a

small, raised ridge slightly below the peristome.

The two teeth are equidistant externally but

strongly diverge as they continue 1.4 mm into

the ai)erture. They may be observed as two white

lines through the thin shell. The expanded

peristome is continuous across the parietal wall

and slightly elevated. The upper shell surface is

marked by fine, curved spiral striae evenly

spaced from the protoconch until the penultimate

whorl where they become irregularly spaced and

larger, resembling wrinkles more than striae.

Ventrally, the striae are fine, evenly spaced to

the peristome and continue to the umbilicus. The

entire .surface is covered by rows of structures

termed cuticular scales by Clench and Miller

(1966:2). The scales are embedded only in the

periostracum.

Measurements ^mm):

Genitalia: The genitalia of Ashmunella sprouli

(fig. 10) are similar to those of A. bequaerti as

de.scribed by Clench and Miller (1966:3). However,

they differ in several respects. The penial retrac-

tor muscle is attached to the epiphallus much

higher than the attachment site on A. bequaerti

and the epiphallus itself is much shorter, but the

flagellum is much longer. The most obvious dif-

ference is in the length of the prostate gland. In

.4. Itequaetii. it travels the entire length of the

uterus touching the albumen gland. In the new

species, it extends only half the length of the

uterus. Externally, the peristome of A. .sprouli is

Vol. 92 (1)

January 31, 1978

The Nautilus 13

^^.t/n^"-

8

9

FIGS. 1-3. Ashmunella sprouli Fnllington and FuUington. new speciex. Haliiti/pe: X2.1: FIGS. 4-6. A. bequaerti (lench

andMUler. 1966; Topotype: XZl: FIGS. 7-9. A. mudgei Cheatum. 1970. Holntype: X1.8.

continuous forming a raised shelf across the

parietal wall and the umbilical diameter is smaller.

Although, the two species are externally similar

with the exception of the peristome, we feel that

the new species merits specific rank based upon the

several differences in the two reproductive systems.

Opposition of Specimens: holotype, Dallas

Museum of Natural History (DMNH 5355);

paratypes deposited California Academy of

Sciences, Delaware Museum of Natural History

(no. 119484) and United States National Museum.

Tyjje Locality: Davis Mountains, Jeff Davis

County, Texas. Spring No. 10 on north wall of

Hell's Canyon just west of junction with Frazier

Canyon 30° 40' 10" N Lat.. 103°5' 15" W Long.

(U.S.G.S. map. Casket Mountain Quadrangle, 1972);

Elev. 5500'; R. E. Sproul Ranch.

Habitat: On 24 July. 1975, forty-one (11 living)

specimens of the new species were collected in a

small talus slope just above the small spring

emerging from a sheer igneous cliff face. The cliff

is located in Hell's Canyon on the R. E. Sproul

Ranch just north of Fort Davis, Texas. The col-

luvium is surrounded by dense, low vegetation.

14 The Nautilus

January 31. 1978

Vol. 92 (1)

large Red Oak trees (Quercus gravessii). Ash (Prajc-

inua cuspid fit ii), Walnut (Juglans microcarpa) and

Buckeye (Aesculus sp.). Maidenhair fern (Addian-

tnni sp.) was abundant on rocks by the spring.

Water from the spring cascaded almost 100 feet to

the canyon floor. Specimens were dug from

under leaf covered rocks. Rain was falling at

the time of collection, but no live specimens

were observed above ground. The collecting par-

ty consisted of the Dallas Museum staff

members: Steven Runnels, Charles Meister.

Ray Garza and the senior author.

FIG. Ill Ashmunella sprouli Pullingtm and Pidiingtun. rinv

species. Genitalia ofparat^)f. (DMNH 5356).

GO -Genital Orifice

LSP - I/iwer Sac of Penis

PR - Penial Retractor Mus-

cle

EP - Epiphallus

VD- Vas Deferens

T - Talon

OV- Oviduct

UT - Uterus

HD - Hermaphroditic Duct

A -Atrium

US? - Upper Sac of Penis

SP - Spermatheca

FL - Flagellum

VA - Vagina

AG ■ Albumen Gland

SD - Spermathecal Duct

PR - Prostate

COMPARISONS

This new species is the third Aahmunella to be

described from the Davis Mountains: Ashmunella

inwlgci Cheatum (1970) (fig. 7 to 9) from

Sawtooth Mountain on the west side and

Ashmunella bequaerti (fig. 4 to 6) Clench and

Miller (1966) which occurs in Goat Cave Canyon

located ten miles north of Hell's Canyon. A.

mudgei is a large, smooth shelled Ashmunella

and bears no resemblance to A. bequaerti or to

this species, although Bequaert and Miller

(1973:39) considered A. mudgei a subspecies of ^.

bequaeiii. Specifically, A. bequaerti and the new

species are similar in external morphology and

probably evolved from a single parental st<jck.

The colony oi A. sprouli appears to be relatively

sinall and extremely isolated as the canyon was in-

vestigated for some distance on either

side of the spring and no additional specimens

were collected. This situation is typical of the

larger-sized land mollusks that inhabit the narrow

steep-sided canyons in the Davis Mountains.

Genetic studies will probably indicate that the

whole Davis Mountains Ashmunella are inter-

related but with extreme localized allelic fi.xation.

Preliminary electrophoretic data on the Hum-

boldtiana complex in the Trans-Pecos Mountains

by Fullington and Zimmerman indicates that this

is the case.

This species is named in honor of Mr. R. E.

Sproul a rancher who has been an amateur

naturalist most of his life. He has long en-

couraged and assisted in scientific studies of the

Davis Mountains flora and fauna.

LITERATURE CITED

Bequaert. Joseph C. and Walter B. Miller. 1973. Tlie Mollusks

(if the Arid SmdhiirM >nth an .Arizana Checkli.<st. Tucson

(University of Arizona Press), pp. i-.xvi, 1-271.

(Tieatum, F^lmer P. 1971. A New Species of .A xh mini did from

the Davis Mountains in West Texa.s. Tfii Saiitiliis

84(:i): 107-1(19.

Clench, William J. and Walter B. Miller. UMia A New Species

of Ashmunella from West Texas (Mollusca: Pulmonata).

Rivriiiria. Museum of Comparative Z(x)log\-, No. 244: 1-6

Vol. 92 (\)

January 31, 1978

TTie Nautilus 15

POTENTIAL BIOLOGICAL CONTROL

OF SCHISTOSOMIASIS INTERMEDIATE HOSTS

BY HELISOME SNAILS'

Emile A. Malek and Rebecca R. Malek

Department of Tropical Medicine,

Tulane Medical Center

New Orleans, Louisiana 70112

ABSTRACT

Helisoma, an Ameriran planorhid genm <if mainly northern firshivater snnil.% is

represented by only one or two species in Central America and certain Caribbean

islands. Their distiibution overlaps that of the neotropical and medicxdly impor-

tant snail. Biomphalaria glabrata in only Ptwrto Rico and Guadeloupe. Results of

laboratory studies point to possible use of helisome snails as competitors against

adult B. glabrata. The snails coidd also function to reduce the reproductive poten-

tials of B. glabrata and also act as decoys in absorbing miraeidia of the human

schistosome Schistosoma mansoni.

Interest in biological control of medically im-

portant snails has intensified in recent years, to

serve as an alternative of, or in addition to,

chemical and engineering measures. The reason

for this has been the gradual opposition to the

application of chemical molluscicides, and the

possible side-effects of these compounds. Among

the reviews of the use of biological control have

been Malek (19.56, 19.58), Michelson (19,57),

Mandahl-Barth (1965), Ferguson and Ruiz-Tiben

(1971). Ferguson (1972). and Berg (1964, 1973).

Investigations on certain species of snails as

biological control agents against medically impor-

tant snails include those on Marisa cornuarietis

(Linne', 17,58) (Ferguson and Palmer, 1958;

Oliver-Gonzales and Ferguson, 1959; Demian and

Lutfy, 1965; Ruiz-Tiben et ai. 1969; .Jobin and

Berios-Duran, 1970); on Pomacea spp. (Paulinyi

and Paulini, 1972); and on Helisoma duryi (Ab-

dalla and Nasr, 1971; Rasmussen, 1974).

MATERIALS AND METHODS

An albino NIH strain of Biomphalaria glabrata

was used. Helisoma duryi normale Pilsbry, 1934,

'This study was supported by a U.S. Public Health Service

Research Career Award K6-AI-18.424 to the senior author.

from near Tallahassee, Florida were supplied by

Dr. Robert B. Short, and Helisoma trivolvis len-

tum (Say, 1834) were collected from swamps near

New Orleans, Louisiana. Aquaria used for the ex-

periments were filled each with 12.5 liters of

dechlorinated tap water, and had a small amount

of gravel on the bottom, but were without vegeta-

tion and aeration. The design of the experiments

to test the effect of the presence of the helisome

snails on adult B. glabrata is shown in Table 1.

Each set of aquaria, for example, 1 and 2, 3 and

4, and 5 and 6 were quite identica as to main-

tenance and diet for the snails.

Experiments on the effect of helisomes on the

viability of eggs of B. glabrata were undertaken

at a temperature of 22-24° C in plastic boxes, 17

X 12.5 X 6 cm in size with 800 ml of water.

Four boxes were used, in each of which 5

Helisoma tnvolvis lentum were kept for 3 weeks

without change of water, before introduction in

each of the dishes of 10 newly-laid egg clutches.

Susceptibility of B. glabrata to infection with a

Puerto Rican strain of Schistosoma mansoni in

presence of H trivolvis lentum was tested in 4

boxes similar to those used for the effect on the

eggs. Medium-size, about 6 mm in diameter,

albino B. glabrata, and the helisomes about 10

l(i The Nautilus

January 31, 1978

Vol. !)2 (1)

T.ABLE 1: Experimental Design to Test the Effect of

Helisiime Snails on Binmphalaria ylabrata. T\\e capacity of

each aquarium was 12.8 liters.

mm in diameter were used for this experiment

according to the following protocole: box 1) 10 B.

glabrata and 20 helisomes. 2) 10 B. glabrata and

10 helisomes. 3) 10 B. glabrata and 3 helisomes. 4)

10 B. glabrata alone. In each container 6

miracidia of S. mansoni per snail (B. glabrata)

were introduced. Replicates of each of the 4 ex-

periments were done.

RESULTS

The rate of growth of Biomphalaria glabrata

was slightly greater when associated with

HelLvima durifi (aquarium no. 1), than when

raised alone (aquarium no. 1). This indicates that

there were no ill effects upon adult B. glabrata

when maintained with H. dun/. However, there

was a vast difference in the number of young;

there were 364 offspring in aquarium 1, and only

20 in aquarium 2 in which B. glabrata coexisted

with H. duryi.

Replicates of the above experiment, but using

Hi'lisiiuta trivolvis lentum. from Lfjuisiana. and

different numbers of the component snails, gave

similar results. Table 2 shows that the reproduc-

tive capacity of B. glabrata was hampered by the

presence of H. trivohns lentum. Such a drastic ef-

fect can be deduced by comparing the number of

offsprings in aquarium No. 3 and 4, and also No.

5 and 6. During the first month of the ex-

periments B. glabrata laid eggs when in ass(X'ia-

tion with the helisf;mes in aquaria 4 and 6, but

many of the eggs failed to hatch, and there was

mortality among the hatched embrv'os. Beyond

the first month, egg laying by B. glabrata was

minimal. As to growth rate of B. glabrata the

snails grew normally in greatest diameter during

the first two months, but beyond this period their

growth was slow or was arrested.

In the experiments to test the susceptibility of

B. glabrata to infection with 5. ynansoni in

presence of H. trivolvi.'^. the infection rates in the

4 groups were as follows: 10%, 20%, 50% and

90%. Replicates of these experiments resulted in

the following infection rates in B. glabrata: 0"h,

10%, 40%, and 90% respectively. Thus the in-

crease in the infection rates of B. glabrata was

proportional to the decrease in the number of H.

trivoims present in each experiment (group),

pointing to the possible use of the latter snails as

decoys in absorbing miracidia of the schistosome.

DISCUSSION

The fact that there were no deaths among

Biomphalaria glabrata in aquarium 2 and that

TABLE 2: (irowth Rate and Reproduction of Hidiiiphdldnii (/lnhrdld when maintained alone or in as,sociation with

Helisome Snails. I) = average diameter in mm: 0 = nunilier nf (iffsprin^'.

Vol. \)2 (1)

January 31, 1978

The Nautilus 17

these snails grew, more or less, at the same rate

as those in aquarium 1 indicate that there were

no ill effects upon adults of B. glabrata due to

the presence of Helisomn durifi. However, there

was a vtist difference in the breeding rate of B.

glabi'ata in the two aquaria. This difference was

also confirmed in the other two sets of aquaria.

Evidently, breeding of B. glabrata was con-

siderably affected in the presence of either

species of the helisomes. The detrimental effect of

the helisomes on the egg clutches of B. glabrata

in other experiments was also evident, as was

observed by Abdalla and Nasr (1971). This might

suggest that excretions or secretions from the

helisomes affect the reproductive jjotential of B.

glabrata. In the experiments on the susceptibility

rates of B. glabrata to S mansoni there was a

consistent reduction of these rates as the number

of helisome snails increased. This points to the

fact that helisomes absorb a good number of the

miracidia of the schistosomes possibly acting as

decoys, as has already been suggested by Chernin

(1968), and Rasmussen (1974).

Although results of laboratory experiments

should not always be indicative of what happens

in natural habitats there is evidence of competi-

tion between helisome snails and B. glabrata as

indicated by the data from the literature and our

own observations of the geographical distribution

of helisomes and the susceptible snail hosts of S

mansoni in the neotropics. Observations on the

natural geographical distribution of Helisoma

spp. point to their possible use as biological con-

trol agents of medically important snails such as

Biomphalaria spp. in Africa and the neotropics

and of Bulinus spp. in Africa and the Middle

East.

Although most species of Helisoma are

temperate climate snails in North America, a few

species are adapted to and occur in the subtropics

and tropics of the Americas. The genus is not

represented in Africa or Asia. In the neotropics

species of Binmphalaria. such as B. obstructa, B.

nisei. B. albicans and B. fieldii, share habitats

with a few species of Helisoma. However,

helisomes do not occur in the geographical zone

of distribution of the medically important

neotropical B. glabrata. B. ,sfra??n'nm or B.

tenagophila. except in a small overlap zone in the

Caribbean, and probably Venezuela. In Puerto

Rico, Harry and Hubendick (1964) reported B.

glabrata co-existing with Helisoma foveale

(Menke, 1830) in two habitats. The senior author

has collected Helisoma spp. from Panama, El

Salvador, Colombia, and Mexico. He did not en-

counter helisomes on Saint Lucia (Malek, 1976)

nor on Grenada, but helisomes are known to oc-

cur on Guadeloupe and Martinique. Helisoma

dunji a species common in Florida has been in-

troduced into the Distrito Federal and two other

habitats in Brazil (Paraense, personal com-

munication).

Other snails which have been advocated for

biological control of Biomphalaria glabrata are

Pomacea spp., and Marisa comvarietis. However,

both Pomacea and Marisa are neotropical and in

certain habitats they occur together with B.

glabrata. The senior author encountered several

localities in western EJahia in Brazil, where large

numbers of Pomacea and B. glabrata co-exist. In

Africa species of the genus PUa, an ampullarid

closely related to Pomacea co-exist with Biom-

phalaria spp. and Bulinus spp., hosts of S. man-

soni and S haematobium respectively.

In addition to helisomes acting as competitors

against the medically important biomphalarids

and bulinids they can also serve as decoys in ab-

sorbing a large number of the miracidia as

demonstrated in this study, and as reported by

other workers. It has been demonstrated by us

and by other workers that helisomes cannot act

as suitable hosts for the schistosomes. Helisomes

certainly deserve to be considered as biological

control agents either by being competitors, intox-

icators or decoys. Other suggested forms of com-

petitive displacement of the medically important

B. glabrata has been by the use of other species

of Biomphalaria. such as B. tenagophila and B.

.'itraminea, and in this case the competition is

termed interspecific competitive displacement

(Barbosa, 1973). Observations by the senior

author in Bahia, Brazil, support the apparent

displacement under natural conditions of B.

glabrata by B. straminea. Interest in such forms

of biological control has arisen from the fact that

18 The Nautilus

January 31, 1978

Vol. 92 (1)

these measures are inexpensive tx) apply. They re-

quire minimal training of the personnel, no

equipment and have no chemical side effects.

Thus while we are making use of the information

which has been gained about chemical control of

snails for the last 2 or 3 decades, we should also

be considering effective biocontrol.

LITERATLT^E CITED

Abdalla, A., and Nasr. T. 1973. Helisoma H. duryi as a means

of biolopical control of schistosomiasis vector snails. Jimr.

Eymit. Med. Asuoc. 56:514-.520.

Barbosa, F. S. 1973. Possible competitive displacement and

evidence of hybridization between two Brazilian species of

planorbid snails. MaUwulngia 14:401-408.

Berg, C. (). I9ly\. Snail control in trematode diseases; the

possible value of sciomyzid larvae, snail-killing Diotera. In

Admmref: in Parasitology (B. Dawes, ed), 2:259-.309.

Academic Press.

Berg, C. 0. 197.3. Biological control of snail-borne diseases: A

review. Erper. Parasit. 33:318-3.30.

Chernin. E. 1968. Interference with the capacity of

SchiMoxiinifi maiisoni miracidia to infect the molluscan

host. Jdur. ParoRitol. 54:.t09-.516.

Demian. E. S. and Lutfy-. R. G. 196.5. Predatory activity of

Mansn cornuarietis against Biomphnlnria nlexnndrina

under laboratory conditions. Ann. Trop. Med. Pnraxit.

59:3.37.

Fergu-son, F. F. and Palmer, J. R. 1958. Biological notes on

Mmisa c.nmnmnpti% a predator of Attst ralorbis glabratiis,

the snail intermediate host of schistosomiasis in Puerto

Rico. Am. Jour. Trop. Med. Hyg. 7:M0.

Ferguson, F. F.. and Ruiz-Tiben. E. 1971. Review of biological

control methods for schistosome-bearing snails. Ethmp. Med.

Jour. 9:95-l(M.

.Jobin. W. R. and Berrios-Duran, L. A. 1970. Cost of

harvesting and spreading Mnriin rornuariet ix for biological

control of Biomphalnna glnhratii in Aibonita. Puerto Rico.

Bull. md. Hlth. Org. i2:m-.

Malek, E. A. 19.56. Factors conditioning the habitat of bilhar-

ziasis intermediate hosts of the family Planorbidae.

WHO/Bil. Eeol./26, 30 August 19.56. Also 19.58. Pull. H7rf.

Hlth. Org.. 18:7aW!18.

Malek. E. A. 1962. Report on precontrol studies of bilharziasis

in St. Lucia. Plan American Health Organization /World

Health Organization, mimeographed document.

Mandahl-Barth. G. 1965. A possible biological method of con-

trolling bilharzia snails. Mimeographed lecture. Ain Shams

Univ. Cairo. 9 pp.

Michelson, E. H. 19.57. Studies on the biological control of

schistosome-bearing snails. Predators and parasites of-

freshwater molluscs. Review of literature. Parasitology

47: 413-426.

Oliver-Gonzalez. J. and Ferguson, F. F. 19.59 Probable

biological control of schistosomiasis in a Puerto Rican

watershed. .4m. Jour. Trop. Med. Hyg. 8: .56-.5.9.

Paulinyi, H. M., and Paulini. E. 1972. Laboratory observations

on the biological control of Biomphalarui glahrata by a

species of Pomacea (Ampullariidae). Bull. Wld. Hlth. Org.

46:21.3-247.

Rasmussen, 0. 1974. Biological control of Biomphalaria pfeif-

feri by Heli.<!onia durifi. Pror. .i)-d Intematl. Congress

araxit.. Munich, Section GI:1.598-1.5;».

Ruiz-Tiben, E., Palmer. J. R., and Ferguson. F. F. 1969.

Biological control of Biomphalaria glahrata by Mariia cor-

muirie.ti.i in irrigation ponds of Puerto Rico. Bidl. H7d.

Hlth. Org.. 41:329-.33.3.

Vol. 92 (1)

January 31, 1978

Tlie Nautilus 19

NESOVITREA SUZANNAE.

A NEW ZONITID LAND SNAIL

FROM COASTAL SOUTHERN TEXAS

W. L. Pratt, Jr.

Museum of Natural History

Uniyersity of Nevada, Las Vegas

Las Vegas, Nevada 89154

ARSTRACT

Nesovitrea suzannae Pratt is a new zonitid. land snail from leaf litter in live

oak groves of Aransas County, Texas. It is distinguished from other North

American Nesovitrea species by its diameter of 2.25 to 2.5 mm, umbilicus 16% to

21% of diameter, lack (f spiral scvlptiirr. and pinkish hroum. color.

In April of 1974 a field party of the Fort Worth

Museum of Science and History, making general

natural history collections in southern Texas, col-

lected a casual leaf litter sample in Goose Island

State Park. When sorted some months later the

sample proved to contain a small series of an

undescribed land snail of the family Zonitidae.

I^ter sampling of the same locality provided more

material, including living specimens.

Nesovitrea (Perpolita) suzannae

new species

r>iagnosis: a small Nesointrea, 2.5 mm or less in

diameter, translucent pinkish brown in color, with

fewer than four whorls, umbilicus less than 22% of

diameter, and without spiral sculpture.

Description: shell depressed heliciform, whorls 3

1/2 to 37/8, slowly increasing, periphery rounded,

aperture ovate-lunate, lip simple; diameter 2.25 to

2.5 mm, height 47% to 51% of diameter; umbilicate,

the umbilicus 16% to 21% of diameter. Irregular

growth striae strongly developed above periphery,

barely discernable on base, shell otherwise smooth,

without sprial sculpture. Fresh shell translucent

pinkish brown.

Atrium long, simple; penis strongly clavate, apex

bluntly rounded, the slender and delicate penial

retractor muscle inserted well below the apex,

slender atrial end of penis without internal folds,

internal walls of swollen apical half with complex

internal folds forming a reticulate pattern; a mem-

branous sheath visible at insertion of epiphallus;

epiphallus entering penis will below apex, walls of

epiphallus simple, without glandular thickening;

vagina short; spermotheca a clavate sac, tapering

slightly toward insertion. Length of penis .6 mm,

length of epiphallus .6 mm. Ek)dy of living snail

light gray.

Holotype: United States National Museum of

Natural History, (USNM 711140); type locality:

Goose Island State Park, 1 mile east of Lamar,

Aransas County, Texas. Sifted from leaf litter in

grove of coastal live oak (Quercus virginiana L.), 19

April 1974, W. L. Pratt, W. R. Barber et al.

Paratypes: deposited in the Fort Worth Museum

of Science and History (FWMSH 3201). the Dallas

Museum of Natural History (DMNH), and in the

author's collection (WLP 1528). Additional

paratypes collected on 1 December 1974 at the type

locality have been deposited in the author's collec-

tion (WLP 1529) and will be distributed to major

natural history museums.

Measurements:

(All specimens fully mature; all measurements by ocular

micrometer.)

20 The Nautilus

Januar>' 31, 1978

Vol. 92 (1)

FIGS. 1. 2 and 3. Nesovitrea suzannae Pratt, new species.

Hiiliil tflii: (immi>ter 2..') mm.

Discuasinn: Neaomtrea dalliann (Pilsbry and

Simpson) of Florida and coastal Georgia differs

from N. .'iuziinndi- in color, has more whorls (4 to 4

1/2), a wider umbilicus (22.5% to 27% of diameter),

and is larger (2.66 to 3.35 mm). A^. subhyalinia

(Pfeiffer) of Mexico is larger with a more depressed

shell and weak spiral striae. A^. electrina (G<;)uld),

known from the Texas Pleistocene, and A^. hin-

neijana (Morse) are northern species, both much

larger with somewhat wider umbilicus and dif-

ferent color. The penial retractor is inserted on the

apex of the penis in both A^. electrina and A^. hiu-

neyanu. in addition to numerous other differences

in detail (Baker, 1930); neither of the other

American Nesovitrea has been dissected.

A single Texas species, Glyphyalinia roemeri

(Pfeiffer), might be confused with A'', suzannae in

drift material. G. roemeri is larger, with closely-

spaced, regular radial grooves; fresh material is

translucent yellowish white. G. roemeri. so far as

presently known, is restricted to the uplands of

central Texas, well away from the coastal range of

N. suzannae, but might be found in river or beach

drift.

Nesoritrea s:iizannae is known only from the

type locality. The minute snails of the region are

FIG. 4. Nesovitrea suzannae l^ntt. new .tperie.t. Outliur Hrtiw-

Iny iifthe anteritir ycnilalia afa ))iimUij>e. scale tine equals 0.1

mm.

j)oorly known, however, and A^. suzannae is pro-

bably widespread in the live oak groves of the

Te.xas coastal prairie. Living snails in the original

sample had been mostly young juveniles with a few

lingering adults, suggesting that the species pro-

bably breeds in late winter and early spring. An

additional collection made in early December, 1974

was composed of large juveniles and young adults,

strengthening the evidence for a late winter

breeding season. At the tyf)e locality A^. suzannae

inhabits leaf litter of a grove of coastal live oak

(Qxercus mrginianm L., s. str.) with a dense

understory of yaupon (Ilex vomitoria Ait.) and red

bay (Persea borbonia (L.) Spreng.). The litter forms

a layer about 4 cm thick on Pleistcx'ene beach sands

with little or no development of soil horizons.

Nest)ritrea suzanna.e is named for my wife, in

recognition of her assistance in the field and her

patience at home.

LITERATURE CITED

Biiker. H. B. IMl. The North .American Retinellae. Pr<ir. .Acad.

.\'at. Srh Philadelphia 82: 193-219.

Vol. 92 (1)

January 31. 1978

TTie Nautilus 21

ASPECTS OF THE REPRODUCTIVE CYCLE

IN MACOMA BALTHICA (BIVALVIA)

Mary Ann Gilbert'

Department of Zoology

University of Massachusetts

Amherst, Massachusetts

ABSTRACT

77ie reproductive cycle and sex ratio by size in a poptdation of Macoma balthica

at Rand harbor, Falmoidh. MA, were determined by dissecting live, measured

animals taken from monthly samples (October 1969 to August 1970) and examining

the gonads. Several specimens, representative of the stages of gonadal development

observed macroscopically, were fixed for histological study. The histological ap-

pearance of gonadal development is very similar to that reported by Caddy (1967)

and Lavoie (1970). There appears to be but one, annual reproductive cycle in M.

balthica at Rand Harbor, with spairning occuning in May. Gonadal regeneration

starts by late fall an gonadal growth continues thnmghout the winter. There ap-

pears to be no significant deviation from a 50:50 sex ratio at any size at Rand

Harbor:

In molluscan species with extensive latitudinal

ranges, spawning in wadely separated localities

occurs at different times (Lammens, 1967; Giese,

1959). For example, populations of Mya arenaria

(Ropes and Stickney, 1965; Shaw, 1965), Spisula

solidissima (Ropes, 1968), and Mercenaria

mercenaria (Porter, 1964, cited in Ropes, 1968)

spavvTi once a year in the northern portions of

their range, but twice a year to the south.

The reproductive cycle in Macoma balthica (L.)

has been studied at several localities: Bay of

Mecklenberg. Baltic Sea (von Oertzen. 1972); Den

Helder. the Netherlands (Lammens, 1967); the

Thames estuary at Whitstable, Kent, England

(Caddy. 1967); the Saint Lawrence estuary.

Cacouna-est, Quebec. (Lavoie, 1970); Malpeque

Bay, Prince Ekiward Island (Sullivan, 1949); the

Saint Croix estuary and Birch Cove in Passama-

quoddy Bay, Saint Andrews, New Brunswick

(Battle, 1933); and the Tread Avon River in the

Chesapeake Bay, Maryland (Shaw, 1%5). I

'Present address: 1017 Main St., Ottawa, Kansas 66067

studied the reproductive cycle of M. balthica at

Rand Harbor, Falmouth, Massachusetts, in-

termediate between the Canadian and Maryland

sites, to clarify latitudinal patterns.

METHODS

Samples of M. balthica and water -column

temperatures were taken at approximately

monthly intervals from October 1969 to August

1970 from the zone of greatest abundance in the

intertidal area at Rand Harbir. Spadesful of mud

were washed through a 2 mm mesh sieve and the

animals removed and taken to the laboratory.

Sex and gonadal condition were examined after

removal of the left shell valve and mantle lobe.

Sex is easily determined by the color of the

gonad: ovaries are gray to gray -orange and testes

are white (Battle, 1933; Lammens, 1967: Caddy.

1967). Eggs are also often visible through the

body wall. As a histological check on the visual

determination of gonad condition, 25 specimens

(total) were chosen as representative of all stages

22 The Nautilus

January 31, 1978

Vol. 92 (1)

TABLE 1. Date, water temperature and number (IN = 228)

of .U lidUhira examined at each o)llection at Rand Harbor.

of gonadal development from the animals ex-

amined in March, May, June and August. The

visceral masses of these specimens were fixed in

Rossman's fluid, imbedded in paraffin, cut at

5-10^, mounted on slides and stained with

hematoxylin and eosin.

RESULTS

The gonad was observed to invest the visceral

mass in a slightly different pattern from that

detailed by Caddy (1967), so a different system of

classification was used to chart the development

of maturity. The gonad was first visible just

below the pedal retractor muscle (fig. la,), but

sexing was not possible at this time (immature

stage). The gonad then grows down among the

coils of the hindgut and through the central por-

tion of the foot (Stage A), and finally appears

dorsal and anterior to the stomach (Stage B; fig.

la). Stage C (pre-spawming) is marked by a strik-

ing swelling of the visceral mass due to a rapid

increase in the volume of the gonad. For up to

two months after spawning, the visceral mass is

in the "spent" condition. It appears flaccid with a

glassy hyaline surface and contains visible

gonadal remains. As the animals recover from

spawning, the gonad remains are resorbed and

the gut becomes clearly visible through the body

wall (undifferentiated stage); sex is again in-

distinguishable at both the macro- and

microscopic levels.

Histologically, the cycle is basically the same

as reported by Caddy (1967) and Lavoie (1970). I

was unable to confirm Caddy's observation that

the gonia were concentrated near the pedal

ganglia after spawning. Rather, the observed pat-

tern of gonadal proliferation (fig. la) supports

Lavoie's findings that the germinal cells are first

found around the genital pores near the internal

dorsal pallial cavity.

Fig. lb presents the percentage of animals in

each stage of development throughout 1969-70 at

I 00 -]

75

% SO

25

0

Undifferentiated and

J

M

J

J

F M A

Month

FKl. 1, a. Diagram showing the .several .stapes of gonadal

maturity of .If halthiai at Rand Harbor. Lines labeled A. B

show the dorsal extent of the gonad at stages A and B; F,

foot; I'RM, pedal retractor muscle; VM, visceral mass.

.Anterior is to the left.

b. Percentage (N = 228) of M hallhirn in each stage of

gonadal maturity during 11 months at Rand Harbor. Stages

.■\ and B are a.s diagramed in la; see text (p. 22) for the

description of the remaining stages.

Vol. 92 (1)

January 31, 1978

TTie Nautilus 23

Rand Harbor. There was clearly only one

reproductive cycle, with spawning occurring

largely in May and finishing by early June.

Recovery occurs over the summer and into the

fall, and gonadal regeneration starts by late fall.

Gonadal growth progresses slowly and steadily

until February, when it speed up in preparation

for spawning.

Table 2 presents the percentage of male, female

and undifferentiated individuals in each size

category (5 to 13+ mm) for all animals ex-

amined. Individuals become sexually mature at

about 8 to 10 mm in length, i.e. at the end of

their first year (Gilbert, 1973). Although Caddy

found that small (4 to 10 mm) specimens are

predominantly male with the sex ratio ap-

proaching 50:50 as animals become larger, there

appears to be no significant deviation from a

50:50 sex ratio at any size at Rand Harbor. This

discrepancy may be due to the fact that very few

M. balthica are 4 to 6 mm in length at the end of

their first year at Rand Harbor.

DISCUSSION

As in the pelecypod species mentioned in the

introduction, M. balthica appears to have but one

spawning season in the northern part of its range

and two in the southern portion (fig. 2). The tim-

TABLE 2. Percentages of male, female and undiffertiated

M. balthica in each size cat^ory collected throughout one year.

ing of these seasons varies, but seems to be tied

to the annual periods when the seawater ranges

from 7 to 14°C. In Passamaquoddy Bay (Saint

Croix and Birch Cove; Battle, 1933), the water

warms much more slowly and evenly than in

other localities and reaches a peak of only

12-14°C by late summer, explaining the delayed

spawning season there. Sullivan's (1948) data

show that planktonic larvae are only found for

three o four weeks at temperatures warmer than

15°C, implying that spawning occurred during

the immediately preceding period when

temperatures rose from 10-15°C within a week.

Lammens (1%7) concluded from laboratory and

field observations that the critical temperature

conditions may indicate hospitable conditions for

larval survival; and both the coincidence of

spawning with neap tides (Battle, 1933; Caddy,

1967) and the rapid rate of development at low

Month

M A M J J

Q fg Temperature cluri nq

spawning ("C)

7-14

8-14

15-17

0-13

12

12-16

Source

van Oertzen

1973

Caddy

1967

Lammens

1967

Sullivan

1948

Lavoie

1970

Battle

1933

Gilbert

Shaw

1965

FIG. 2. Dates and temperatures of the water during spawning seasons of Macoma balthica (rf various locations.

24 The Nautilus

January, 31, 1978

Vol. 92 (1)

temperatures (Gilbert 1975) may be adaptations

to help ensure return of the larvae to the adult

locality.

Two characteristics of this species' reproductive

cycle emerged. First, gonadal growth occurs

throughout the winter (fig. 1; Caddy, 1967; Lam-

mens, 1967; Lavoie, 1970). As Lammens points

out, since M. balthica feeds on the substrate, its

food source is available throughout the year. Se-

cond, there is an alternation of growth in size

and gonadal development: the annual period of

rapid increase in length (Gilbert, 1973) occurs

during the gonadal recovery period (fig. lb). Lam-

mens and Lavoie also observed such an alterna-

tion for animals at Den Helder and Cacouna-est

(Saint Lawrence), resjaectively.

The age of sexual maturity does vary. On the

Thames it occurs during the second year (at 5 to

6 mm length; Caddy, 1967), whereas in the

Netherlands first year animals larger than 4 mm

contained gonads during the spawning season

(Lammens, 1967). At Cacouna-est, sexual maturi-

ty is not achieved until the second year (mean

length of 3.57 mm), as first year animals (2.34

mm) did not spawn their sexual products (Lavoie,

1970). Cx)nsidering that the growth rate varies

widely among different populations of M.

balthka (Gilbert, 1973), this species may mature

sexually during the second year, regardless of

size, and during the first year if a certain size (4

mm) is reached.

ACKNOWLEDGMENTS

This study was conducted at the Systematics-

Ecology Program of the Marine Biological

Laboratory. Woods Hole, Massachusetts, was sup-

ported in part by an NDEA Title IV Fellowship

and was submitted to the University of

Massachusetts at Amherst, as part of a dtx'toral

dissertation. I wish to thank the Part-Time

Graduate Fellowship Program of the Radcliffe In-

stitute for their support and Dr. A. C. Scott, Pro-

fessor Emeritus, for allowing the use of the

facilities of the Department of Biology at Colby

College. I also gratefully acknowledge the advice

of Drs. D. C. Edwards and H. E. Potswald who

read and commented on early manuscripts of this

paper.

LITERATURE CITED

Battle, H. 1933. Rhythmic sexual maturity and spawning of

certain bivalve mollusks. Cont. Can. Biol. Fisheries n. s. 7:

2.57-276.

Caddy. .J. F. 1%7. Maturation of gametes and spawning in

Maaimii balthim (L.) Can J Zml. 45: 955-96.5.

Giese, A. C. 1959. Comparative physiology: annual reproduc-

tive cycles of marine invertebrates. Ann. Rev. Phyfnol 21:

547-576.

Gilbert. M. A. 1973. Growth rate, longevity, and maximum

size of Maeoma balthica (L.) Biol. Bull. 145: 119-126.

Gilbert, M. A. 197,5. Distribution, reproduction, feeding, and

growth of Macoma balthica (L.) in New England. Ph.D.

dissertation University of Massachtisett.t at Amherst. 120

pp. (University Microfilms publ. no. 75-27, 514).

Lammens. J. .J. 1967. Growth and reproduction in a tidal flat

population of Macoma balthica. Neth. J. Sea Res. 3: 315-382.

Lavoie. R. 1970. Contribution a la biologie et a I'ecologie de

Macoma balthica L. de I'estuaire du Saint -Laurent. Ph.D.

dissertation. University Laval de Quebec. 249 pp.

Ropes, J. W. 1968. Reproductive cycle of the surf clam, SpisuJa

solidissima. in offshore New Jersey. Binl. Bull. 135: .349-.365.

Ropes. J. W., and A. P. Stickney. 1965. Repnxiuctive cycle of

Myaarenaria in New England. Biol Bull. 128: 315-.327.

Shaw. W. N. 196.5. Seasonal setting patterns of five species of

bivalves in the Tred Avon River, Maryland. Ches. Sci. 6:

.33-37.

Sullivan. Charlotte M. 1948. Bivalve larvae of Malpeque Bay.

P.E.L Fish. Res. Bd. Can. 77: 1-36.

von Oertzen. J.-A. 1972. Cycles and rates of reproduction of

six Baltic Sea bivalves of different zoogeographical origin.

Mar Biol 14: 143-149.

Vol. 92 (1)

January 31, 1978

The Nautilus 25

EFFECTS OF

POLLUTANTS ON NATALITY OF

MUSCULIUM SECURIS (BIVALVIA: PISIDIIDAE)

G. L. Maekie

Department of Z<x)log>', University of Guelph

Guelph, Ontario, NIG 2W1

ABSTRACT

LaboraUiry expenments show that natality o/Musculium securis is significantly

reduced below 10°C and above 25°C with optimum reproduction close to 18°C. Road

salts consisting of sodium chloride have a greater adverse effect than similar con-

centrations of salts consisting of calcium chloride on the natality of laboratory

reared M. securis. Natalities are significantly less in sulfate concentrations ex-

ceeding 100 tng/1. When reared in the field, reproduction o/M. securis is reduced

immediately below pulp and paper outfalls and sewage and slaughter house waste

discharges. It is conchtded that natality is a good index for the assessment of

water quality. Guidelines are given to standardize techniques for calculating a

natality index from naturally occurring populations of sphaeriixis.

A plethora of indices using benthic organisms for

the assessment of water quality has been developed

in recent years. Nearly all require species identifi-

cations of several groups of benthic organisms.

Perhaps the oldest and most commonly used are

the pollution indicators (e.g. Tubifex tubifex and

Chironomus plumosus) whose presence in large

numbers usually indicate organic enrichment

(Gaufin 1973). Long lists have been published of

plants and animals classified as indicators of dif-

ferent degrees of pollution (Kolwitz and Marsson

1908, 1909; Richardson 1929; Sladacek 1973). Lists

of groups of indicator organisms have been made

for calculating biotic indices, such as the Trent

Biotic Index (Woodiwiss 1964) and the Beak Biotic

Index (Beak 1%5). Use of diversity indicies based

on information theory (Wilhm and Dorris 1968;

Pielou 1967, 1969) are being used in assessment of

water quality with increasing frequency in the

literature.

All extant biotic indices require good quan-

titative samples to be able to calculate accurate

population sizes for each taxon. However, there are

numerous sources of error that are inherent in the

various methods needed for accurate population

estimates (Cummins 1962). For example, there are

no sampling devices that sample all communities

on all substrates equally well resulting in selectivi-

ty of gear for certain benthic groups (Flannagan

1970). There is usually loss of some organisms

through conventional sieves during washing pro-

cedures (Jonasson 1955; Reisch 1959; Maekie and

Quadri 1971). The methods that have been

developed for separating the organisms from the

debris are invariably selective for certain groups

(e.g. flotation, Anderson 1959, Whitehouse and

Lewis 1966; fluorescent dyes, Hamilton 1969;

elutriation, Moon 1935). Finally, the taxonomy of

some groups, especially of larval chironomids at the

species level, is poorly known and the identification

of all taxa within a community is time consuming

and often requires confirmation or identification

by experts.

Clearly, there is need for a biotic index that does

not require quantitative samples nor identification

of species within numerous taxa. These obstacles

largely can be reduced with the use of natality data

from a single group of organisms. Natality is a

useful parameter because it is a measure of popula-

tion increase under an actual specific environmen-

tal condition varying with the size and composition

of the population and the physical environmental

26 The Nautilus

January 31, 1978

Vol. 92 (1)

conditions (Odum 1971). The prerequisites for

choice of organisms are (a) they should be

cosmopolitan in distribution, and (b) they should be

viviparous or ovoviviparous (i.e. bear living young)

since oviparous organisms usually lay numerous

eggs (often uncountable) that are often hard to

find. The most cosmopolitan benthic organisms are

oligochaetes, chironomids, and sphaeriids, and of

these, only the sphaeriids are ovoviviparous and

bear living young.

The objectives of the present study are to deter-

mine the effects of some common pollutants, tem-

perature, road salts, sulfate, domestic and

slaughterhouse wastes, and pulp and paper effluent

on the natality of a sphaeriid, Muscvlium secwris,

and to assess the use of sphaeriid natality as an in-

dex for assessment of water quality. The effects of

substratum and competition on natality of M.

securis are described elsewhere (Mackie and Qadri,

in press; Mackie, Qadri, Reed, in press). M-nsculium

secwris was chosen as the test animal because it is

cosmopolitan in distribution and grows and

reproduces relatively quickly in the laboratory

(Mackie 1973).

MATERIALS AND METHODS

Natality in sphaeriids is relatively easily deter-

mined by one of two methods. The simplest method

is to place one to five newborn clams into grow^th

containers, allow them to grow and reproduce

under a specific set of environmental conditions

either in the laboratory or in the natural habitat,

and count the number of newborn produced after a

definite interval of time. For M. securis this inter-

val of time is the life of the clam (60 to 80 days)

since the parents usually die after producing a lit-

ter of newborn. For multivoltine species the con-

tainers must be examined at more frequent inter-

vals. Mean natality is determined by dividing the

total number of newborn produced in the con-

tainers by the number of parents (i.e. adults that

reproduce).

Since the first method requires at least eight

weeks to obtain results (from M. securis) the second

method is preferred where natality data is needed

in one or two days. However, a knowledge of larval

development in sphaeriids is required. A brief

description follows but detailed descriptions of life

history of M. securis are given by Mackie, Qadri,

and Clarke (1975, 1976) and of other species by

Heard (196.5, 1977).

In sphaeriids there are four arbitrarily defined

stages of larval development that occur on the in-

ner gill; these are embryos, fetal larvae, pro-

dissoconch larvae, and extra-marsupial larvae. Em-

bryos are contained within single-walled primary

sacs and include all stages from the zygote through

gastrulation. When the shell begins to form the lar-

vae are known as fetal larvae and the enveloping

brood sac forms a second wall to become a secon-

dary brood sac. TTie prodissoconch larva is the third

developmental stage including formation of the

shell up to but not including escape from the

double-walled tertiary sacs in which they are in-

cubating. The shelled larvae that have broken free

from the tertiary sacs are known as extra-

marsupial larvae and they are contained within the

marsupium prior to birth. All four larval stages

may be found on an inner gill in species of

Musculium but only one developmental stage is

usually found at one time in species of Pisidium

and Sphaerium.

There is usually some mortality between each

larval stage with more mortality occurring be-

tween fetal and prodissoconch larvae than between

prodissoconch and extra marsupial larvae. There

is very little or no mortality at the extra -marsupial

stage and more than 99% of these larvae are viable

at birth in M. securis (Mackie, Qadri, and Clarke

1976). Therefore, in the second method it is impor-

tant to account for extra-marsupial larvae. Care

must be taken, when examining a sample, to ensure

that none of the extra-marsupial in a litter have

been bom (i.e. newborn are not present in the sam-

ple). Counts of prodissoconch larvae are also useful

since they can be used to determine numbers of

extra-marsupial larvae in a litter if amount of mor-

tality between these two stages is known. A sample

of 50- UK) specimens of a species is sufficient for

calculating a reliable estimate (P<0.05) of mean

natality.

After trj'ing several methods, I found that a com-

bination of soil (from a willow-elm forest), leaves,

and water was the best medium for maintaining M.

securis in the laboratory. Newborn M. securis were

obtained from Carp Pond (Mackie, Qadri and

Clarke 1976) and grown in 100 mm dia X 50 mm ht

Vol. 92 (1)

January 31, 1978

TTie Nautilus 27

"Pyrex" dishes (= growth dish) containing 50 g

(oven-dry basis) of air-dried soil, (from Carp Pond),

2 g of air-dried black willow or white elm leaves,

and enough distilled or deionized water to fill each

dish. One day was allowed for equilibration, and

then usually five newborn M. securis were added.

These were allowed to grow, reproduce, and die

(60-80 days). Dishes were topped daily with

distilled or deionized water and examined every

two weeks to determine how many adults were

bearing larvae (shells are transparent enough to

see if larvae are present). Dishes were otherwise

left undisturbed, e.g. without aeration. At the end

of the experiment, when at least 75% of the parents

(usually 100%) were dead, the numbers of newborn

produced within each dish were determined.

Temperature - To determine the effects of

temperature on the natality of M. securis, adults

were grown in constant temperature rooms at 5°C,

10°C, 18°C, and 25°C. Other conditions, such as light

intensity, appeared to be similar in each room but

were not measured. TTiree dishes with five newborn

in each were maintained at each temperature.

Road salts - To determine the effect of road salts

on the natality of M securis, newborn were grovm

in various concentrations of rock salt, calcium

chloride (CaCU), and sodium chloride (NaCl). The

rock salt was obtained from the storage sheds of the

Ontario Department of Highways. The chemical

composition (by weight) of the rock salt as specified

by the Ministry of Transportation and Communica-

tions of Ontario (pers. comm.) had a moisture con-

tent of less than 0.5%, a sodium chloride content of

more than %.0%, and insoluble matter of less than

4.0%. Concentrations of 200, 400, 600, 800, and 1000

mg/1 of each salt were made using deionized water.

Growth dishes were prepared as described above

but in replicates of three and using the solutions of

different salt content rather than distilled water.

Three control dishes (i.e. soil, leaves, and deionized

water) were also prepared with five newborn clams

in each.

Sulfate - The effect of sulfate on the natality of

M securis was determined by maintaining adults

in sulfate (in sulfuric acid) concentrations of 0, 20,

40, 60, 80, 100, 200, 300, 400, and 500 mg/1. Natality

of M. securis was determined as described earlier

but in replicates of three for each concentration of

sulfate solution. The final sulfate concentration in

each dish was taken as the concentration of sulfate

added plus that which went into solution from the

soil used in the growth dishes. Sulfate concentra-

tion was determined on water samples taken from

each dish using a modification of the turbidimetric

technique of Toennies and Bakay (1953). These

modifications are described elsewhere (Mackie

1973).

Organic and Industrial Pollutants - Growth

tubes were made to maintain M. securis above and

below municipal sewage and industrial outfalls.

The tubes were made out of 35 mm dia X 60 mm ht

plastic vials with snap-on caps. Two 1 cm X 4 cm

rectangular holes were cut from the lower sides and

covered with nylon mesh to permit flow of water

through the tubes. Twenty growth tubes, each con-

taining one newborn M. securis from Britannia

Bay of the Ottawa River near Ottawa, were placed

at each distance of 50 m, 330 m, 700 m, and 1000 m

below the outfalls of a pulp and paper plant in the

Ottawa River. Another twenty tubes were placed

immediately upstream of the outfalls as controls.

Twenty tubes were also placed 1.6 km below a

slaughterhouse and several raw sewage outfalls;

growth tubes placed in Britannia Bay were used as

controls. All growth tubes were placed in less than

one meter of water. The number of young produced

by parents in each tube was recorded at the end of

the experiment.

RESULTS

Temperature

Of the four temperatures tested, the greatest

natality occurred at 18°C (Table 2). The optimum

temperature for reproduction was between 10 and

25°C, probably close to 18°C.

Road salts

Increased concentration of rock salt and pure

sodium chloride had greater adverse effects on the

natality of M. securis than did calcium chloride

(Table 2). Natalities were greater in control dishes

than in experimental dishes containing rock salt or

sodium chloride. Lower natalities occurred in high

concentrations of CaCl than in control dishes but

differences were not significant primarily because

of the large variations in natality that occurred

among dishes.

28 The Nautilus

January 31. 1978

Vol. 92 (1)

Sulfate

The following table gives the pH and sulfate con-

tents of the test solutions before and two weeks

after adding sediments. TVie results show that the

pH decreased with increasing concentration of

sulfate. Also, the increase in pH after adding sedi-

ment indicates the high buffering capacity of the

soil in the dishes. The amount of sulfate that went

into solution from the sediment tended to decrease

with increasing concentration of sulfate, in the

prepared solutions.

TABLE 1. Changes in the pH and sulfate concentrations of

water after adding Carp Pond soil to the growth dishes.

Concentrations of sulfate less than 100 mg/1 had

no significant effect on the natality of M. securis

(Table 2). Significant reductions in natalities oc-

curred in concentrations exceeding 100 mgS04/l.

Most clams in these concentrations formed blackish

shells.

Raw sewage and slaughterhouse wastes

There was no reproduction of M. securis in a

creek carrying raw sewage and slaughterhouse

wastes (Table 2). The qualities of the waters in the

creek and control stations are given in Table .'1

Ptdp and paper wastes

Natalities of M. securis were significantly

greater (P<0.05) above the outfalls than below the

outfalls and tended to increase with increasing

distance below the dutfalls (Table 2).

As many as eight leeches of the species,

Helobdella stagnalis, were present in the growth

chambers above the outfalls. The mortalities of M.

securis in the chambers were low and most pro-

duced young so that the leeches had little effect on

the production of first litters of young. Most M.

seniris adults died by the end of August in the con-

trol tubes but it is not known whether they died of

natural causes or leech predation.

High mortalities of M. securis occurred in

growth tubes below the outfalls. No leeches oc-

curred in the growth tubes below the outfalls.

Premature deaths of adults were probably at-

tributable to chemicals or other properties of the

effluents. Table 4 gives .'^ome physical and chemical

properties of the water at various distances from

the outfalls during the study period.

DISCUSSION

Effects of Pollutants

Mackie (1973) showed that growth of M securis

at 10°C in the laboratory was minimal and that in

the natural habitat growth did not appear to begin

until about 8°C. Similar results have been reported

for other sphaeriids. e.g. M. partumeium (TTiomas

1965) and S. comeum (Tliiel 1927; Mitropolskji

1966) and several freshwater gastropods (van der

Schalie and Berry 1973). These results suggest that

many sphaeriids should be absent or depauperate

in waters where the mean temperature is less than

10°C, although some (e.g. Pisidium conventus and

Sphaerium nitidum) are seldom found in

temperatures above 10°C, Herrington 1962).

Mackie (1973) also showed that the upper

threshold of tolerance for M. securis was less than

SOT and the present study would indicate that

reproduction probably ceases between 25 and 30°C.

Other species, e.g. M. partumeium CHiomas 1959)

have even lower thresholds, close to 2rC. These

results suggest that many sphaeriids would be ab-

sent in waters where the mean temperature ex-

ceeds 25°C.

High concentrations of rock salt and sodium

chloride have a greater adverse effect on the

reproduction of M securis than do high concentra-

tions of calcium chloride. Smaller natalities occur

with increased concentrations of rock salt and

sodium chloride, particularly in concentrations

greater than 200 mg/1. The results obtained using

calcium chloride are more difficult to explain.

Vol. 92 (1)

January 31, 1978

The Nautilus 29

Clams show higher natality with increased concen-

tration of calcium chloride but natality in all con-

centrations studied are less than those observed in

the control dishes. The reasons for this are not clear

but it is possible that chloride has an adverse effect

while calcium has a stimulating effect on the

reproduction of M. securis. If this interpretation is

correct then the adverse effects of chloride are

more pronounced at low calcium chloride concen-

trations and the stimulating effects of calcium are

more pronounced at high concentrations.

The results also indicate that road salts could be

a major factor in limiting the distribution of M.

siecuru;. This is particularly true in northern

latitudes where sodium chloride is used in the

winter months to remove ice from roads. The ef-

fects of road salts on growth, reproduction and

distribution of other sphaeriids have not been

reported in the literature.

The present study indicates that natalities of M

securis are not significantly affected by sulfate un-

til exposed to concentrations exceeding 100

TABLE 2. Mean natalities of Mmculium aeniris adults showing the effects of temperature, rock salt, sodium chloride, cal-

cium chloride, sulfate, pulp and paper waste and raw sewage and slaughterhouse wastes. Means side-.scored by the same lines

are not significantly different at P = 0.0.5. Standard deviation of the mean in parentheses.

30 The Nautilus

January 31, 1978

Vol. 92 (1)

TABLE 3. The means and ranges of several factors of the water below a slaughterhouse and several raw sewage outfalls.

Each mean is based on five water samples taken at approximately two week intervals in the summer of 1971. All values

are in mg 1 unle&s otherwise indicated

Biochemical oxygen demand — given in Mackie (1973)

MPN = Most Probable Number - given in Mackie (1973).

mgS04/l. However, as the sulfate concentration is

increased, the pH decreases. Therefore, it is dif-

ficult to determine whether pH or sulfate is the

limiting factor. Since the same inverse relationship

usually exists between pH and sulfate in the

natural habitat, it can only be concluded that high

sulfate concentrations would have either a direct or

indirect effect on the reproduction of M. securis.

High concentrations of sulfate may also limit the

distribution of M. Kcruri.'^ although specimens have

been collected near Sudbury, Ontario (see collec-

tion in National Museum of Canada, #NMC 28610)

where sulfur dioxide is a serious atmospheric pollu-

tant (Rao and Leblanc 1967). In the presence of

moisture, sulfur dioxide forms sulfurous acid which

is slowly oxidized to sulfuric acid; the acid in turn

is converted to sulfates such as amonium and

calcium sulfate (Johnstone and Coughanow 1958).

The effects of sulfate on the growth and reproduc-

tion of sphaeriids, and indeed on other mollusks,

have not been reported in the literature.

It is apparent that M. securis cannot tolerate

gross chemical and/or organic pollution of pulp

and paper, slaughterhouse, and raw sewage ef-

fluents. It is not possible to identify those factors in

the effluents that affected the reproduction of M.

securis although the water quality data indicates

that large B.O.D. 's and coliform bacteria counts

may be important factors. Since M. securis often is

exposed to very low oxygen levels (less than 1 ppm)

in temporary aquatic habitats (Mackie 1973), it is

doubtful that oxygen was a limiting factor in the

Vol, 92 (1)

January 31, 1978

The Nautilus 31

growth of M. securis below the outfalls. Thomas

(1965) also concluded that oxygen was not a

limiting factor in the growth of M parinmeium.

The effluent below the pulp and paper mill car-

ried large quantities of wood fibers but very little

entered the chambers in which M. securis adults

were maintained. Therefore, growth of M. securis

below the pulp and paper outfalls probably did not

represent the added effects of wood fibers.

The increase in reproduction of M. securis with

increased distance from the pulp and paper outfalls

indicates that the species could survive in recovery

zones. However, as indicated above, the environ-

ment in the growth chambers may not have been

representative of the environment in the "natural"

habitat below the outfalls. Wurtz (1956) suggest

that M. securis, as well as several other sphaeriids,

"can survive, at least to some degree, in the zones of

degradation and recovery", Ingram et al (1953) con-

clude that Sphaerium strixitinum (&?, S. solidulum)

cannot tolerate intensive pollution from domestic

sewage but that it may respond to a slight fertiliza-

tion effect from domestic sewage by increased pro-

ductivity. Kehr et at (1941) and Purdy (1930) con-

sider the Sphaeriidae as a group of sewage-tolerant

organisms while many others (Morgan 1930;

Carpernter 1928; Baker 1922) associate them with

clean waters.

Use of Sphaeriid Natality as an Index of Water

Quality

The results of the pollution studies indicate that

natality of M securis is generally either directly or

inversely related to the intensity of the concentra-

tion of a pollutant. This implies that the natality of

M securis is potentially a good index of en-

vironmental stress. However, before natality of

sphaeriid species can be used as an index of water

quality, the effects of various pollutants must be

determined for several species (especially for com-

mon species such as Sphaerium striatinum,

Pisidium casertanum, Pisidium compressum,

Pmdium nitidum, and all Mitsculium species) since

some, e,g. 5. striatinum, respond to slight fertiliza-

tion by increased productivity (Ingram et al 1953)

and others by decreased productivity. Also, because

of the heterogeneity of the natural habitat and the

multiplicity of interacting factors (e.g. sediment

texture, competition, temperature, etc.) ex-

periments should be done in the field on natural

populations. Stations should be established above

TABLE 4. The means and ranges (in parentheses) of several factxjrs of the water at various distances above and below a

pulp and paper outfalls. TTie values are based on five water samples taken at approximately two wek intervals. All values

are in mg/1 unless indicated otherwise.

oValues determined by Mackie (1971)

32 The Nautilus

January 31, 1978

Vol. 92 (1)

(= control) and at several distances below the out-

falls. Habitat characteristics should be similar, ex-

cept for those features altered by pollution, and

natalities should be compared with those in the

control stations. It is essential that at least two

control stations be established to detect differences

that may occur from one site to the next in the

unaltered habitat. Also, control stations account

for variations in natality that may occur from one

year to the next and among different bodies of

water.

If these criteria are met, then any changes in

water quality would be accompanied and be

detected by changes in the natality index. Values

significantly less than those obtained in the control

station would indicate deterioration in water

quality. Values significantly greater than those ob-

tained in the control station would indicate that

the species responds to the ambient conditions by

increased productivity. The habitat that supports

the highest natality would probably be the habitat

most characteristic of the species. Therefore, if a

species is more prolific in organically enriched

areas, it is probably an indicator of those condi-

tions.

Applying the index to the Ottawa River, the

highest natality in the natural population of M.

.spcwm in 1972 was obtained in Britannia Bay, the

control station (2.44. Table 2). Although a small

sample size (12), the mean natality of M. securis

below the pulp and paper outfalls (off east end of

Kettle Island, Mackie and Qadri 1973) in 1972 was

1.70 young per parent (standard deviation = 0.55).

This is significantly less (P<0.05) than that ob-

tained in Britannia Bay, indicating a deterioration

in water quality.

The advantage of using natalities as indices of

water quality are far reaching. Most significant is

that quantative estimates of population sizes are

not necessary and samples of sphaeriids need not

be obtained with quantitative sampling techni-

ques; it is necessary only to obtain a sufficient

number of any species of sphaeriid that has a por-

tion of the population in the process of reproduc-

tion. The number of extra-marsupial larvae

(shelled larvae lying free in the marsupium and

ready for birth) or prodissoconch larvae are deter-

mined for each parent and the mean natality per

parent is then calculated as described in materials

and methods. Enumeration of other larval stages

provides other important criteria such as per cent

viability of larvae and larval mortality rates

(Mackie, Qadri and Clarke 1976). Another ad-

vantage is that water quality can be assessed long

before conditions become aggravated if sphaeriid

species common in cleaner water are examined.

This is in direct contrast to pollution indicator

organisms that diagnose water already grossly

polluted.

Although this study indicates that natality is

potentially a good index for assessment of water

quality, considerably more studies are needed be-

fore its validity can be fully assessed. For e.xample

more data is needed to show variations in natality

within several species taken from several different

kinds of habitats. Ft is not known if species that re-

quire two and three years to complete their life

cycles can also be used for natality indices. Studies

are needed to determine if natality indices can be

used to characterize different degrees of pollution,

i.e. subpollution, gross pollution. Undoubtedly,

many more questions will be asked as more pro-

blems are solved.

ACKNOWLEDGEMENTS

This research was supported by the National

Research Council of Canada, Grant Nos. A2:386

awarded to S. U. Qadri, Biology Department.

University of Ottawa, Ottawa and A9882 awarded

to the author.

UTERATURE CITED

Anderson. R. C. 1959. A modified flotation technique for sorting

bottom fauna samples. Limnol. Oceanix/r. 4:223-12.5.

Baker. F. C. 1922. The molluscan fauna of the Big Vermillion

River. Illinois. Illinois Biol. Mnnof)): 7: 1-26.

Beak, T.W. 196,5. A biotic index of polluted streams and its rela-

tionship to fisheries, pp. 191-210. In: Advances in Water Pollu-

tion Research. Proc. Second Intemat. Conf. held in Tokyo,

1964. Pergamon Press, Oxford. Vol. I. :?73 pp.

Carpenter. K. E. 1928. Life in Inland Water. Sedgwick and

Jackson, Ltd., Ijandon, 627 p.

Cummins. K. W. 1962. An evaluation of some techniques for the

collection and ;inalysis of benthic samples with special em-

phasis on lotic waters. ,4 mpr. Midi Nat. 67:477-.504.

Flannagan , .J. F. 1970. Efficiencies of various grabs and corers in

.sampling freshwater benthos. Jour. Fish. Res. Bd. Can.

27:1691-1700.

Vol. 92 (1)

January 31. 1978

The Nautilus 33

Gaufin, A. R. 1973. Use of aquatic invertebrates in the assess-

ment of water quality, pp. 96-116. In: Biological Methods for

the Assessment of Water Qnaliti/. Cairns. J. and K. L. Dickson

(Eis.).Amer.S(x: Testing Materials. Philadelphia, PA 2r)6p.

Hamilton. A. L. 1969. A method of separating; invertebrates

from sediments using longwave ultraviolet light and fluores-

cent dyes./rwr. Fish. Res. Bd. Can. 26:1(567-1672.

Heard, W.H. 1965. Comparative life histories of North

American pill clams (Sphaeriidae: Pisidium). Matacologia

2:381-411.

Heard, W. H. 1977. Reproduction of Fingernail Clams

(Sphaeriidae: Sphaerium and Muscidium). Malaeohx/ia

16(2): 421 -i.5.5.

Herrington. H. B. 1962. A revision of the Sphaeriidae of Nort

Americi (Mollusca: Pelecypoda). Misc. Pithl. Miis. ZooL.

r«ic. A/iWayori. No. 118. 74 p.

Ingram. W. M., D. G. Ballinger, and A. R. Gaufin. 195:3. Rela-

tionship of Sphaerium snlididttm Prime to organic pollu-

tion. Ohio Jour. Sci. 53:230-235.

Johnstone, H. F. and D. R. Coughanow. 1958. Absorption of

sulfur dio.xide from air. Indus. Eng. Chem. 50:1169-1172.

Jonasson, P. M. 1955. The efficiency of the sieving techniques

for sampling fresh -water bottom fauna. Oikos 6:183-207.

Kehr. R. W., W. C. Purdy, et al. 1941. A study of the pollu-

tion and natural purification of the Scioto River. Public

Health Bidi. 276: 1-153.

Kolkwitz, R. and M. Marsson. 1908. Okologie der

pflanzlichen Saprobien. Ber. dt. Bot. Ges. 26A: 505-519.

1909. Okologie der tierischen Saprobien. Inter-

nal. Rev. Hydrolbiol. 2: 126-152.

Mackie. G. L. 1973. Biology of Museulmm seairis

(Pelecypoda: Sphaeriidae) in two temporary forest ponds,

a river, and a permanent pond near Ottawa. Canada.

Ph.D. thesis, Univ. Ottawa, Ottawa, Ontario. 175 p.

Mackie, G. L. and S. U. Qadri. 1971. A new sieve and tub

trough for washing substrate samples aboard a boat. Pro-

gre^ive Bsh-Cult urist 33:112-115.

1973. Abundance and distribution of Mollusca in

an industrialized portion of the Ottawa River near

Ottawa-Hull, Canada. Jour. Fish. Res. Bd. Canada

30:167-172.

xMackie, G. L, S. U. Qadri. and A. H. Clarke. 1975. In-

traspecific variations in growth, birth periods, and

longevity of four populations of Musculium securis

(Pelecypoda: Sphaeriidae). iV/a/cKo/ogia 15:433-446.

1976. Reproductive habits of four populations of

Musculium securis (Pelecypoda: Sphaeriidae) near Ot-

tawa, Canada. The NaidUus 90:76-86.

Mitropolskji, W. I. 1966. "Observations of the life cycle of

Sphaeriutn comeum L. (Mollusca: Lamellibranchia)" and "On

the mechanisms of filtration and the feeding habits of

Sphaeriidae (Mollusca: Lamellibranchia)" Eiigiish transla-

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vodeomov", Akademiya Nauk SSSR, Institut Biologii

Vnutrennikh Vod, Trudy, vypusk 12(15. 1966.

Mixm, H. P. 1935. Fl(K)d movements of the littoral fauna of

Windemere. Jour. Anim. Ecol. 4:216-228.

Morgan, A. H. 1930 Fietdbook ofPomh and Streams. G. P. Put-

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Odum. E. P. 1971 (2nd Ed.). Fundamentals of thiUyn. W. B.

Saunders Co., Toronto, Ontario. 574 p.

Pielou, E. C. 1967. The use of information theory in the study of

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1969. An Introduction to Mathematical Ecology.

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Purdy, W. C. 1930. A study of the pollution and natural purifica-

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Rao. D. N. and F. Leblanc. 1967. Influence of an iron-sintering

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40:307-309.

Richardson, R. E. 1929. The bottom fauna of the middle Illinois

River. 1913-1925: its distribution, abundance, valuation and

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Sladacek. V. 1973. System of water quality from the biological

point of view. Arch. Hydrohiol. Beih. Fjrgebo. Limnd. 7:1-218.

Thiel. M. E. 1927. Versuch, die Verbreitung der Arten der Gat-

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Thomas, G. J. 19.59. Self-fertilization and production of young in

a sphaeriid clam, ne Nautilus 72:131-140.

1965. Growth in one species of sphaeriid clam. The

Nautilus 19:4"-5i.

Toennies. G. and B. Bakay. 1953. Photonephelometric

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van der Schalie and Berry. 1973. (Abstract) The effects of

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Malacol. Rev. 6:60.

WTiitehouse. J. W. and B. G. Lewis. 1966. The separation of ben-

thos from stream samples by flotation with carbm

tetrachloride. Li'TO7io/. Oceanogr. 11:124-126.

Wilhm. J. L. and T. C. Dorris. 1968. Biological parameters for

water quality criteria. Bioscience 18:477-481.

Woodiwiss, F. S. 1964. The biological system of stream classifica-

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11:44.3-447

Wurtz, C. B. 1956. Fresh-water mollusks and stream pollution.

The Naidilus 69:96-100.

34- The Nautilus

January 31, 1978 Vol. 92 (1)

RANGE EXTENSION OF MOLLUSKS

FROM THE MIDDLE ATLANTIC BIGHT

Arthur S. Merrill'

Robert C. Bullock^

David R. Franz^

ABSTRACT

New northern and southern range and depth extensions off Eastern United

States of 67 species of mollusks colteeted alive by R/V DELA WARE Cruise 60-7

are repoHed. including 3 scaphopods. SO gastropods and 3U bivalves. Cylichna

linearis Jeffrei/s (0})isthobranchiata: Cylichnidae) is reported in Western Atlantic

waters for the first time.

TTie U. S. Bureau of Commercial Fisheries* con-

ducted a routine cruise (R/V DELAWARE Cruise

60-7) in the middle Atlantic Bight from &pe Cod,

MA, to Cape Hatteras, NC, during 11-21 May 1960.

Eight major transects with selected stations be-

tween the transects were made; in all, 113 stations

were occupied in depths of 26 to 146 meters (fig. 1).

The primary reason for the cruise was to in-

vestigate the abundance and distribution of the sea

scallop, Placopecten magellanicus (Gmelin). In ad-

dition to a 10-ft (3.05 m) standard offshore dredge

used to collect the scallops, a small 30-in (76.2 cm)

Digby dredge with a 1/2-in (12.7 mm) liner was

towed at all stations to collect a sampling of the

biota associated with the scallops. The scallop data

were analyzed and reported (Merrill, 1962). The

material collected in the lined Digby dredge was

slowly sorted, identified, and tabulated as time

allowed and the information is being used where

appropriate. Several specific studies incorporating

faunal data acquired from DELAWARE Cruise

60-7 have been published. Those relating to range

' National Marine Fisheries, Service Northeast Fisheries

Center, Woods Hole. MA 02543

' Department of Zoology, University of Rhode Island,

Kingston. RI02H81

' Department of Biology. Br(X)klyn College of the City Univer-

sity of New York. Brwiklyn. NY 1 1210.

' Now National Marine Rsheries Service.

extensions and species distribution are briefly sum-

marized below.

Galtsoff and Merrill (1962), studying shell mor-

phology, grow1;h, and distribution of the crested

oyster, Ostrea equestris Say. extended the range of

this oyster northward. Merrill and Webster (1964),

surveying oceanic commercial clam distribution,

defined the major populations of Spisiila

solidisgima (DiWwyn) and Arctica islandica (Linne)

in the middle Atlantic Bight. Boss and Merrill

(1965), monographing the family Pandoridae,

clarified distributional patterns of Pandora species

occurring in the middle Atlantic— the ranges of P.

arenosa Conrad, P. trilineata Say and P. infJata

Boss and Merrill were extended northward; and P.

gouldiana Dall, was extended southward. Merrill

(1970), working with the family Architectonicidae,

found a new species from the offshore waters of

Virginia and North Carolina. Merrill, Emery and

Rubin (1965), reporting the significance of fossil

shells of Crassostrea mrginica (Gmelin) on the floor

of the ocean off the middle Atlantic coast,

estimated the time and positions of former sea

levels and deduced probable former estuaries after

the end of the latest glacial epoch through the

distributional pattern of the oyster relics and

radiocarbon dating techniques. Merrill (1967),

assessing the possible adverse effects of the hydroid

eipzoan, Hydractinin echinata (Fleming), on sea

scallops, defined the offehore distribution of the

Vol. 92 (1)

January 31, 1978

The Nautilus 35

Bbch Island "' ^

\J- 1-' ^0 I i i_ong Island

08 1 Cape Hat teras

FIG. 1. Location of stations occupied during a survey of the

middle Atlantic shelf (DELA WARE Cruise 60-7). Stations are

identified by dnts. major transects by dashed lines.

hydroid in the middle Atlantic. Edwards and Mer-

rill (1977), reconstructing the continental shelf

areas of eastern North America for the times 9,500

B.P. and 12,500 B.P., discussed the distribution and

age-depth relationship of Holocene fossil-shell

deposits of C. virginica and Mesodesma arctatum

(Conrad). These and other studies underway give

an indication of the breadth of use of the data to

date.

This paper records the range extensions of the

mollusks, other than those mentioned above, taken

during DELAWARE Cruise 60-7. Table 1 includes

the previous range and depth and the new range ex-

tension, the number and condition of the specimens

and the stations and depths from which the

mollusks were taken. Shells from recently dead

animals can be distinguished from weathered and

fossilized material by the luster and fresh ap-

pearance of the shells. Only live or recently dead

specimens were used to determine new range and

depth extensions. The depth is included in the

range extension column only if the known

bathymetric range is extended. Range extensions of

32 species are noted in Table 1—22 northward, 9

southward, and one species is recorded in western

Atlantic waters for the first time. Depth ranges

were also extended for 16 of the 32 species.

Our record of Cylkhna linearis Jeffreys (fig. 2)

from off Wachapreague Inlet, VA, is the first time

this European species has been reported from the

western Atlantic. This species was introduced as a

variety of C. cylindracea Pennant, but noted to dif-

fer by its smaller shell and the possession of

brownish spiral lines at each end of the shell. With

regard to other western Atlantic members of the

genus, C. linearis must be compared with C. ver-

rillii Dall. The former species is larger, possesses

the numerous spiral brown lines, and the greatest

width is toward the anterior end of the shell, not at

the middle.

Two Species, Coins islandicm (Gmelin) and

Bwcinum undMum Linne, have been reported to

range south to South Carolina (Dall, 1903). Later

workers have restricted their range well to the

north— C. islandicm to Labrador and arctic

Canada; B. undatum to New Jersey in depths to

several meters (Johnson, 1934; Abbott, 1974). Bush

(1885) failed to find either species in dredgings

from six stations north of Cape Hatteras, NC, in

depths of 26 to 265 m. Porter (1974) had no record of

them south of Cape Hatteras in North Carolina,

nor had Merrill and Petit (1965, 1969) from South

Carolina. Clarke (1954) found C. islandicm south of

Georges Bank, MA, to east of Chincoteague Island,

VA, in 155-759 m. We now record C. islandicus

from off Block Island, RI, and off Cape Henry, VA,

FIG. 2. Cylichna linearis Jeffreys. R/V DELA WARE Cruise

60-7. Sta. 5-J,, off Wachapreagw Inlet. VA. llCnn. Length, 10

mm.

36 The Nautilus

January 31, 1978

Vol. 92 (1)

in 42-146 m. It is quite possible that Dall's report of

('. istandicm living at depths of 37-3017 m and

ranging to South Carolina is correct but only if the

species is living in very deep water, beyond the

deepest stations (146 m) made on the DELAWARE

Cruise 60-7 transects.

Dal! (1903) reported the range of B. xmdntiim to

Charleston, SC, but with a question mark, in depths

of 0 to 1189 m. We found B. undatum to be one of

the most ubiquitous species in our samples from

the middle Atlantic shelf. In all, the species was

taken at 42 stations, alive at 28 of them southward

to Cape Henry, VA. In addition, egg cases with no

adults were collected at three stations. To conserve

space only stations with live animals are listed in

Table 1. On the basis of the completeness of our

data for this species we conclude Dall's southern

distributional and depth ranges are invalid. No live

specimens were found at the deeper water stations

of the eight major transects (fig. 3). The distribu-

tion of live specimens and weathered or

fragmented shells of B. undatum from our cruise

were similar latitudinally, but the dead material

occupied somewhat deeper waters on the average.

Live specimens were recorded to a depth of 73 m;

fragments were taken at three stations as deep or

slightly deeper, from 73 to 84 m. Dredge tows were

made at 32 stations along the coast in waters as

deep as 73 m or deeper to 146 m. The species was

not found at these deeper waters stations. In con-

trast, the species was taken at most of the shallow

water stations. Below Barnegat, NJ, at 10 stations,

the depth averaged 49.5 m for live specimens; at 1 1

stations 66. 2 m for dead. Tiis suggests that the

species is living close to its depth limits. A further

analysis of the depth and thermal distribution of

this and other species is in preparation.

Our transect off Currituck Beach, VA, is about

70 nautical miles north of Cape Hatteras, NC. In

compiling Table 1 we arbitrarily designated Cur-

rituck Beach as a starting point to record range ex-

tensions above Cape Hatteras. The ratio of new

moUuscan range extensions to species identified

from the cruise is about one to six.

The species listed below were collected at sta-

tions 10 to 30 nautical miles above Cape Hatteras

and confirm existing ranges reported to and slight-

ly north or south of Cape Hatteras.

FIG. 3. Distribution o/Buceinum undatum Linne along the

midiile Atlniitir shelf (DELAWARE Cndse 60-7). Note the

absence o/B. undatum below the Cape Charles transect and at

the deeper water stations on major transects.

Niso aeglccs (Bush, 1885)

'Diria mnltbiana (Schwengel and McGinty, 1942)

A'.s/omo clathrata (Lamarck, 1816)

Tarnin galea (Linne, 1758)

Nasmnui^albm (Say, 1826)

Oliva sayana (Ravenel, 1834)

CijUchnella hidentata (Orbigny, 1841)

Dpntalinm ehoreum (Conrad, 1846)

Fo/rfm/ma<?/ia (Say, 1831)

Atrina rigida (Lightfoot, 1786)

Aequipeden muscoHUi>. (Wood, 1828)

Piicatida gihbosa (Lamarck, 1801)

Liirina riaAvda (Conrad, 1846)

'Lucina radiani^ (Conrad, 1841)

'Diplodonta soror (C. B. Adams, 1852)

Afitartp itndata (CK)uld, 1841)

Aataripciuitanea (Say, 1822)

Euerassatella speciosa (A. Adams, 1852)

Ervilla concentrica (Holms, 1860)

Vol. 92 (1)

January 31, 1978

The Nautilus 37

Tcllina >iqua7}iifern (Deshayes, 1855)

'Ti'llina aeqiiistriata (Say, 1824)

Tdlina altemata (Say, 1822)

'Tellina syharitica (Dall, 1881)

Strigilla mirabilis (Philippi, 1841)

Semele bellastriata (Conrad, 1837)

Chione uitapurpurca (Conrad, 1849)

Chionegrus (Holmes, 1858)

Pilar fulminatus (Menke, 1828)

* Species not reported north of Cape Lookout, NC.

The species listed below were taken at latitudes

10 to 30 nautical miles south of the latitude of Nan-

tucket Island, MA, and confirm existing ranges

reported slightly south of Cape Cod.

Oenopota harpularia (Couthouy, 1838)

Orn(>pi)ta hiearinata (Couthouy, 1838)

Vyrtodariasiliqua (Spengler, 1793)

Thracia septentrionalis (Jeffreys, 1872)

The mollusks from DELAWARE Cruise 60-7

have been accessioned into the mollusk collection at

the Museum of Comparative Zoology.

T.'\BLE 1. List of mollusks with new range extensions collected during RA'' DELAWARE Cruise fif)-7 in the Middle At-

lantic Bight. All parenthesized numbers are depths in meters.

A-2(51):A-16(44);

A-20(64);A-22(51);

A-23(62):A-2.5(37);

A-26(55);A-29(59);

A-32(68): A-34(40):

A-35(40); A -36(40);

A-37(51);A-39(70);

A-43(62):A-44(,59):

A-46(.38):A-47(.51);

A-.54(42); A-.56(48);

Recently dead, weathered or fragmented

taken at 15 stations with living, and at 22

additional stations.

Vol. 92 (1)

January 31, 1978

Tlie Nautilus 39

Sperteii

Family

Paltifihim sub-

imbrifier

(Verrill &

Bush, 1897)

Pecten raveneli

Dall, 1898

Pectinidae

Pectinidae

Cydapecten nanus Pectinidae

(Verrill & Bush,

1897)

Heuromeris tri- Carditidae

dentata (Say, 1826)

Laevicardium laevi- Cardiidae

gatum (Linne,

17.58)

Laei-icardium pic- Cardiidae

turn (Ravenel,

1861)

Ch kme cantellata Veneridae

(Linne, 1767)

PrpmoiUf Range

No and Ctmditum

n/Specimnui

Stai iitm

Range Extenxiim

Off Martha's Vine-

yard, MA (210-667)

Off Cape Hatteras,

NCtoWestIndi«:

Gulfof Mexicx)

(17-75)

Off Chesapeake

Bay, V A to Texas;

Puerto Rico;

Brazil (40-538)

Off Cape Hatteras,

NC to both coasts

of Florida; Gulfof

Mexico (low water

to 227)

Off Cape Hatteras,

NC to both sides of

Florida and the West

Indies; Brazil; Ber-

muda (low water)

to 1.37)

Off Cape Hatteras,

NCto Brazil; Ber-

muda (low water

to 155)

Off Cape Hatteras,

NCto Florida, Texas

and the West Indies

(low water to 110)

10 Living

35 Recently dead

1 Weathered or frag-

mented

1-4(110); 2-1(37);

5-4(110); A-.3(64);

A-.5(64);7-.5(146)

1-4(110);;?- .5(146);

4-5(146);. 5-4(1 10);

A-4(;37); 7-5(146)

3-4(112)

NE of Oregon Inlet,

NC (.37)

3 Recently dead 7-2(37); A-17(62) Off Cape Charles, VA

740 Recently dead

A-l(7.5);5-2(.5.5);

.5-4(110); 6-.3(73);

A-5(64);A-7(.35);

7-4(113); A-20(64);

A-24(84)

1 Weathered or frag-

mented A-24(84)

1 Living

6 Recently dead

A-.5(64)

.5-l(.3.3); 6-2(37);

A-.5(64);A-10(44);

2 Recently dead 7-2(37); 8-2(37)

18 Recently dead

4 Weathered or frag

mented

6-2(37); 7-2(37);

A-9(37); 8-1(26);

8-2(37); A-10(44)

A-ll(33)

-6-3(73); 7-1(33);

8-1(26); 8-2(37)

1 Recently dead 7-1(33)

Off Indian River

Inlet, DE (35)

Off Chincoteague

Inlet, VA

Off Currituck Beach,

NC

Off Cape Henry, VA

Off Currituck Beach,

NC

Chione latilirata

(Conrad, 1841)

Veneridae

Off Cape Hatteras,

NCto Florida and

to Texas; Brazil

(18-227)

11 Recently dead

7-2(37); A-9(37)

A-10(24)

Off Currituck Beach,

NC

Variarrbula oper-

adata (Philippi,

1848)

Corbulidae

Off Cape Hatteras,

NC to Florida to

Texas; West Indies;

Brazil (9-457)

8 Recently dead

6-3(7.3); 7-2(37);

8-2(37); A-10(44)

Off Cape Henry, VA

40 The Nautilus

January 31, 1978

Vol. 92 (1)

Film Uy

frrniiiLt Rilwjf

Nil- and Ciimiitum

iifSfnTimeiiK

Hixiiili Ksti iiy<

Xyluiihngn allantica Pholadidae

(Richards. 1942)

Periphima papi/ra- Periplomatidae

Hum (Say, 1822)

Gulf of St. Law-

rence, Canada to

Cape Henry. VA

(low water to :?718)

Labrador. Canada to

Rhode Island

(11-229.5)

1 Living

7 Living

7 Recently dead

A-9(35)

Off Oregon Inlet, NC

A-42(73):A-.T()(77):

A-.51(7.3);A-.52((ifi)

l-:5(73); 2-3(82);

A-12(73); A-19(81):

A-.')()(77);A-.51(73);

A-.')2(fif;)

OffPt.Plea.sanr.N.1

LITERATURE CITED

Abbott. R. Tucker. 1974. American Seashelh. Van Nostrand

Reinhold Company, New York. 663 pp. (Second E/iition).

Boss. Kenneth J., and Arthus S. Merrill. 19&5. The family Pan-

doridae in the western Atlantic, ./o/in.sowin 4(44): 181-216.

Bush. K. J. 188.5. List of the shallow-water Mollusca dredged off

Cape Hatteras by the "ALBATROSS" in 1883. In: XVI. -

Results of the explorations made by the steamer

"ALBATROSS" off the northern coast of the United States,

in 1883, by A. E. Verrill. Report of the Commissioner for

1883. U.S. Cnmm. Pish and Fishmcs 11: ,579-.590.

Clarke, Arthur H., Jr. 19.54. Some mollusks from the continental

slope of northeastern North America, ft-emora 40: 1-11.

Dall. William H. 1903. A preliminary catalogue of the shell-

bearing marine mollusks and brachiopods of the southeastern

coast of the United States. U.S. Nat. Mus.. Bull No. 37. 232 pp.

(reprint of the 1889 edition).

Eldwards, Robert L., and Arthur S. Merrill. 1977. A reconstruc-

tion of the continental shelf areas of eastern North America

for the times 9.,5(X) B.P. and 12.,5O0 B. P. Archaeology of

Enxterv North America 5: 1-43.

Galtsoff, Paul S., and Arthur S. Merrill. 1962. Notes on shell

morphology, growth, and distribution of Ostrea equestris Say.

Bidl Mar'Sci GulfCanb. 12(2): 234-244.

.lohnson. Charles W. 1934. List of marine Mollusca of the Atlan-

tic coast from Labrador to Texas. Proc. Boston Soc. Nat. Hint.

40(1): 1-2M.

Merrill, Arthur S. 1962. Abundance and distribution of sea

scallops off the middle Atlantic coast. Proc. Nat. Shellfish Ass.

51: 74-80.

Merrill. Arthur S. 1967. Offshore distribution of Hijdractinia

echuuiia. U.S Pish WML Sen:. Pish. Bull 66(2): 281-283.

Merrill, Arthur S. 1970. The family Architectonicidae

(Gastropoda: Mollusca) in the western and eastern Atlantic.

Ph.D. Dissertation, University of Delaware, .3.38 pp.

Merrill. Arthur S., K. 0. Emery, and Meyer Rubin. 196.5. An-

cient oyster shells on the Atlantic continental shelf. Science

147(.36.56): :398-400.

Merrill. Arthur S., and Richard E. Petit. 1965. Mollusks new to

South Carolina. Nautilu.f 79(2): 58-66,

Merrill, Arthur S.. and Richard E. Petit. 1969. Mollusks new to

South Carolina: II. NatitUus 82(4): 117-122.

Merrill, Arthur S.. and John R. Webster. 1964. Progress in surf

clam biological research. In: Tlie Bureau of Commercial

Fisheries Biological Laboratori'. Oxford. .Manland: Programs

and Prospectives. U.S. Pish Wildl. Sen:, Circ. 200. pp.:«-47.

Porter. Hugh J. 1974. The North Carolina Marine and Est uarine

Mollusca— an Atlas <}f Occurrence. TTie University of North

Carolina Institute of Marine Sciences. Morehead City, NC, 351

pp.

Vol. 92 (1)

January 31, 1978

The Nautilus 41

A NEW GENUS OF OPERCULATE LAND SNAILS

FROM HISPANIOLA WITH COMMENTS ON

THE STATUS OF FAMILY ANNULARIIDAE

Fred G. Thompson

Florida State Museum

University of Florida

Gainsville, Florida 32611

Hispaniola is inhabited by many exquisite land

animals. It has an especially rich and diverse

gastropod fauna. Although much has been written

about Hispaniolan mollusks, large geographic areas

remain virtually unexplored for land snails and

many new forms remain to be described. During

the past two years I spent about eight months in

the field in the Dominican Republic and made ex-

tensive collections of land snails from most areas of

the country.

The physiography of Hispaniola is complex. It

consists of many mountain ranges, ridges, and

isolated hills, all of which combine to form a mosaic

of faunal regions. The Cordillera Central consists

mostly of igneous and metamorphic rocks, and

calciphyllic families of land snails, such as the

Urocoptidae and Annulariidae, are conspicuously

absent. Elsewhere, to the north, east, and south,

calcareous substrates predominate. In these areas

some hills and mountain ranges have a high degree

of molluscan endemism. One such mountain ridge

in Puerto Plata Province is inhabited by a most

unusual land snail, whose transparent shell with

high fragile ribs cause it to resemble a giant

snowflake. It is one of the most striking terrestrial

operculates to have been discovered. The trans-

parent, high ribs of the shell is an adaptation for a

cryptic existence on an exposed limestone surface.

The snail is highly unnoticeable because of the

blurred image that is created by its sculpture. This

delicate, ornate sculpture is unrivaled by any other

known species of "cyclostomid," although similar

ornamentation occurs in some members of the

pupinid genus Geothauma from Borneo.

The snail described herein is a member of the

family Annulariidae and the subfamily An-

nulariinae as defined by Henderson and Bartsch

(1920) Controversy exists over the availability of

the generic name Annularia Schumacher, 1817 as

opposed to Choanopoma Pfeiffer, 1848 and An-

nulariidae as opposed to Chondropomidae or

Pomatiasidae (see Henderson and Bartsch, 1920;

Baker, 1924a: 2-3, Solem, 1960: 419-420; 1961: 192-

194). This case is currently before the international

Commission on Zoological Nomenclature. For pur-

poses of this paper I tentatively accept Dall's (1905:

298) type species designation of Turbo lineina Lin-

naeus for Annularia. Annulariidae Henderson and

Bartsch (1920: 54) has page priority over Chon-

dropomi-(dae) Henderson and Bartsch (1920: 59). I

arbitrarily follow the subfamily division proposed

by Henderson and Bartsch (1920) and Baker

(1924a). Later authors, who criticized Henderson

and Bartsch 's classification, did not provide more

useful alternatives. For reasons given below I con-

sider the neotropical Annulariidae and the Old

World Pomatiasidae to be separate families.

Licinae Pfeiffer, 1858 was the first family-group

taxon name used for the neotropical "cyclostomes."

Except for occasional use in the mid-nineteenth

century the name went unmentioned in the

primary literature until Golikov and Starabogatov

(1975) resurrected it as the family name Licinidae.

The name Licinidae Pfeiffer is a nomen oblitum

because of this great time lapse and thus is not

available for use (ICZN Article 23, b).

Field work relating to this study was supported

by the National Geographic Society, Council for

Research, and the Florida State Museum. I am

grateful to officials of both organizations for the

support they have given me. Dr. Joseph Rosewater

(USNM) and Dr. Charlotte Patterson (UMMZ) kind-

ly loaned to me dried specimens of Cistulops and

Ti-osc.hehnndex from which radulae were extracted

42 The Nautilus

January 31, 1978

Vol. 92 (1)

FIG. 1. Meganipha rhecta, new genus and new species, Thompson. A-C. Holntt/pe (I'F 227I,'>). D. P(irati/pe (UF 227!t7).

K Fnnit if/ir (UF 22746).

Vol. 92 (1)

January 31, 1978

Tlio Nautilus 43

for SEM studies. Preserved specimens of PomaYiV/.s

cleganii (Milller) used in this study were collected

by Dr. S. David Webb (Florida State Museum)

while he was a Gugenheim Scholar in France

during 1973. I am grateful to the following people

who assisted me in field work in the Dominican

Republic: Howard W. Campbell, Ronald Crombie,

Richard Franz, Roy McDiarmid, Sylvia Scudder,

Linda Wiley, and especially Beverly E. Johnson

whose energy for hiking up mountains and search-

ing for snails seemed nearly inexhaustible. The

photographs comprising fig. 1 were made by Donna

B. Drake; SEM micrographs were made by Sylvia

Scudder.

Meganipha new genus

Type species: Meganipha rhecta new species.'

This is a genus of the Family Annulariidae, sub-

family Annulariinae. The shell is helicoid with

raised nipplelike apical whorls. Spiral sculpture is

obsolete. It is indicated only by the undulating

bases of the ribs, which occur in spiral sequences.

Otherwise the shell is devoid of spiral sculpture

even in the umbilicus. The axial sculpture consists

of extremely high, widely-spaced fragile ribs that

are about half the diameter of the whorl in height.

The peristome is double. The outer peristome is

very broadly expanded, slightly more so than the

ribs, and is recurved posteriorly along its outer

edge. The face of the outer peristome is sculptered

with numerous close spiral striations.

The operculum bears a raised spiral calcareous

lamella that is reflected laterally so that it

overlaps, but does not fuse with succeeding turns.

The lamella lacks reinforcing ribs or buttresses.

The outermost turn of the lamella is reflected

beyond the basal chandroid plate so that the oper-

culum is too large to be retracted into the aperture.

The relationship of Meganipha to the An-

nulariinae is clearly indicated by its operculum. In

this subfamily it bears a raised spiral calcareous

lamella which may be reflected to parallel the basal

plate. The lamella may lack reinforcing ribs so than

an open cavity is formed between the reflected

' ET\'MOLOGY. Meijaiuphn (f.): from the Greek megas, giant,

and miihn. a snowflake; rhecta: from the Greek rhertas. brittle.

The name Mcijnniphu rhecta Tliompson appears as a nude name

m the Florida State Museum Newsletter. June 1976. vol. .5. p. 8

(fig.).

lamella and the basal plate, or reinforcing ribs may

be present, which partially obstruct the cavity.

Meganipha belongs to an assemblage of closely

related Hispaniolan genera that includes

PeUmpowa, Bartsch, 1946, Rnlleia, Crosse, 1891,

Lagiipoina. Bartsch, 1946. and Abbottella, Hen-

derson and Bartsch, 1920. This group contains

helicoid, depressed-helicoid, or discoidal species

that have a double peristome. The genera are

separated by sculpture, shell shape, and the

development of the opercular lamella. It is beyond

the scope of this paper to review the status of these

genera. However, each is composed of species that

represent natural assemblages, and the use of

generic names for these assemblages is warranted.

Petusipoma has a helicoid shell with both axial and

spiral threads. The operculum is unusual in that

the lamella is reflected to parallel to the basal plate

with successive turns fusing to form a continuous

outer plate. The other genera have a gap between the

successive turns of the lamella. Rolleia is

depressed-helicoid and is characterized by having

axial ribs only. Spiral sculpture is absent.

Lagapoma and Abbottella have spiral sculpture as

well as axial ribs. Lagopoma differs from Ab-

bottella as well as all other Annulariinae by having

a notch in the outer peristome over the parietal

wall. Meganipha differs from these four genera as

well as other annulariids and pomatiasids by its

sculpture and its outer peristome. No other genus

has axial ribs that approach the fragile lamellar

condition characteristic of Meganipha, and no

other described genus has a peristome that is as

broadly expanded and bears the characteristic

lacey concentric sculpture on its face. The obsolete

spiral sculpture on the shell is also characteristic.

The operculum is unusual but not unique within

the Annulariidae in that it is too large to be with-

drawn into the aperture. In the related genera

mentioned above the operculum is retractable in-

ternally.

Meganipha rhecta new species

SHELL (fig. 1). - This is an elegant, medium-

sized snail that is fragile and delicate in structure.

The shell is turbiniform in shape with a slightly

concave spire. Usually the shell is wider than high,

being about 0.90—1.02 times as high as wide. The

last whorl flares laterally conspicuously beyond the

44 Tie Nautilus

January 31. 1978

Vol. 92 (1)

curvature of the spire and has a widely reflected

fragile peristome. The thin shell is transparent

when alive and clearly shows the viscera in-

ternally. The color of the shell is a soft frosty white

on a translucent background. Occasional specimens

have five reddish-brown spiral bands, three on the

base, one on the periphery, and one on the shoulder,

of the whorls (fig. 1, E). The umbilical perforation

is broad, being slightly less than the width of the

last whorl. There are about 5.0-5.6 whorls with 2.2-

2.3 smooth, raised, nipple-shaped embryonic

whorls. The suture is deeply impressed. The first

and second postembryonic whorls are weakly

angular at the shoulder. The body whorl is only

weakly in contact with the preceding whorl and is

solute and descends near its termination, leaving a

triangular gap behind the peristome. The postem-

bryonic whorls are sculptured with elegant, very

thin, very fragile evenly spaced vertical ribs that

are about half as high as the diameter of the whorl.

There are about 10-12 ribs on the last whorl. The

ribs are .strongly undulated at their base but are

flattened near their outer edge. The interspaces are

sculptured with vertical rounded threads and

striations that parallel the basal undulations of the

ribs. Tlie ribs on the earlier postembryonic whorls

are usually broken away, leaving only jagged rem-

nants of their bases. The aperture is slightly higher

than wide, and is oblique, lying at an angle of about

35° to the axis of the shell. The inner peristome

projects forward only slightly. The outer peristome

is very bi'oadly reflected and recurved and is about

half as wide as the diameter of the aperture. It is

thin and fragile and is sculptured on its face with

numerous close raised spiral undulating threads

that give the peristome a lacey appearance. The

threads are densely crowded near the aperture and

are more widely spaced toward the periphery.

Tlie operculum (fig. 1,0) tears a strongly reflect-

ed calcareous lamella which contacts itself on each

succeeding turn so that a calcareous

pseudolamellae is formed on the outer surface

leaving a tubular spiral space beneath it. The

pseudolamellae lacks reinforcing ribs. Usually the

lamella on the inner most 3-4 whorls is broken

away, exposing the basal chondroid plate. The oper-

culum does not withdraw into the aperture, but

lays nearly flush with the peristome.

Measurements of the holotype and four

paratypes selected in show ranges of variation

(measurements in parentheses include only the

caliber of the whorls and not the ribs or outer

peristome).

Radula. - Tlie radula is taenioglossate and ex-

tends posteriorly into the coelom for about 0.5

whorls behind the buccal mass. Basically it is

similar to the radulae of other annulariids in that

the central and lateral teeth are unicuspid. The

transverse rows of teeth are close-set so that the

teeth broadly overlap at their bases, thus rein-

forcing each subsequent row in its cutting action

when feeding (see Solem, 1974, for similar ob-

servations on pulmonates). The central tooth has a

long lanceolate cusp that projects at about 90° to

the base of the tooth. The basal plate is long and

relatively slender and bears a strong reinforcing

fold along each side between which the distal half

of the preceding tooth lies. The lateral teeth are

similar to the centrals, but are broader and the

cusp is slightly longer (fig. 2, A, D-1). The inner

marginal has a single large triangular mesocone

that is rather jagged along its outer edge and bears

a small ectocone at its base (fig. 2, B-im). The out-

side margin of the shaft has a short triangular

flange below the cusp so that the two marginal

teeth interlock at their bases and along their shafts

when in use (fig. 2, B). The outer marginal is

broadly triangular in outline due to a thin mem-

brane that extends from the shaft of the tooth to

the outer end of the cusp margin (fig. 2, B, C-om).

The outer marginal bears about 50 slender, sharp,

sickle-shaped cusps along the cutting edge. The

cusps are largest near the shaft and gradually

decrease in size toward the outer edge.

Reprodiictive system - The male reproductive

system is closed throughout its length and ter-

minates in a long slender penis that is triangular in

cross-section (fig. 3, F]). The penis originates on the

right side of the nape deep within the pallial cavity,

and in a resting pxisition it is recurved over the cen-

ter of the nape so that it is U-shaped with its tip

pointed anteriorly. The vas deferens is very short

and runs transversely along the body wall from the

base of the penis to the prostate. The prostate is im-

bedded in the right wall of the mantle cavity and

lies completely anterior to the transverse wall of

Vol. 92 (1)

January 31, 1978

The Nautilus 45

FIG. 2. Meganipha rhecta, new genus and new species. Thompson. SEM micrographs of mdula fUF 22748). A. Complete

transi'erse section (X 105). B. Marginal teeth (X 260). C. Sickle-shaped cwsps of outer marginal teeth (X 5J,0). D.

Oblique view of central and lateral tooth rows (X 250). E. Lateral and marginal tooth rows (X 245). Legend: T-central,

\-lnteral. im-inner marginal, om-oider marginal.

46 The Nautilus

January 31, 1978

Vol. 92 (1)

capsule gland

antle — ,

albumen gland

posterior wall of mantle cavity

iduct

copulatory

bursa

copulatory

bursa

copulatory /'^^i^^.

bursa i if 2^

oviduct

ovary -

post, wall of mantle cavity

sperm duct

vas deferens

FIG. 3. Meganipha rhecta, ne^r geniLs and new xperies. A. Female reftrodiictive ayslem. B-D.7>"nyerse sections through

copulatory bursa at rnrresponding points on A. E. Male reproductive system.

Vol. 92 (1)

January 31, 1978

The Nautilus 47

the mantle cavity. The testis is fusiform, relatively

stocky, is 1.5 whorls long and lies along the

columellar side of the digestive gland. The sperm

duct is very narrow and thin walled immediately

below the testis. It becomes enlarged along its

lower half, forming a seminal vesicle that is rather

densely pigmented with melanophores. Numerous

small yellow concentration granules of uric acid

are scattered throughout the visceral cavity and

surround all of the visceral and reproductive

organs.

The female reproductive system is tripartite,

consisting of an ovary, the primary oviduct and its

derivatives, and the pallial oviduct (fig. 3, A). The

ovary is elongate-cylindrical and occupies about 1.5

whorls along the basocolumellar side of the

digestive gland. The primary oviduct originates

from the anterior end of the ovary. It is thin-walled

and expands along its lower third to form a densely

pigmented seminal receptacle. The oviduct con-

tinues in the basal wall of the copulatory bursa

RCG—,

(fig. 3, B-D) to the albumen duct, and from there

into the capsule gland. The copulatory bursa is

thick walled and has about 10-12 longitudinal folds

prodtruding into its lumen. An enlarged fold along

the columellar side partially divides the lumen

longitudinally. The lumen continues into the

seminal receptacle by a very narrow perforation at

the posterior end of the bursa. The albumen gland

is strongly compressed laterally. It overlaps the

posterior wall of the mantle cavity so that its

posterior half lies along the columellar side of the

visceral mass and its anterior half borders the man-

tle cavity. The capsule gland is a voluminous

multifolded chamber that is open throughout its

length along the columellar angle of the mantle

cavity and beneath the intestine. It contains about

20 vertical undulating folds which presumably ex-

pand into a large chamber during ovulation, as oc-

curs in Poma<ias(see Creek, 1951: 608-609).

Nervous system (fig. 4, A, B). - The brain is an

advanced epiathroid type in which the pleural

-ROc

FIG. i. Meganipha rhecta, )ww geiutg and new species. Central nervous system. A. Late>-al lieu: B. Dnrsal ririi: Lryend:

LCG-lefl cerebral ganglim. IC-VN-left cerebral-pedal nerve; W-left ocular nerve; LPG-left pedal ganglion: LPlG-left

pleural ganglion; PN-pedal iieri'e.i; RCG-right cerebral ganglim,; R?G-right pedal ganglion; RPlG-riyht pleural ganglion;

RPl-PH-right pleural-pedal nerve; ?hG-s,iboesoph(igeal ganglion; ShN-suhoesophageal nerve: SuG-supnwesophageidganiiliori;

Suii-supranesophageal nerve.

48 The Nautilus

January 31, 1978

Vol. 92 (1)

ganglia are moved dorsally and are fused with the

posterior-lateral corner of the cerebral ganglia. The

nerve ring encircles the center of the buccal mass

midway between the mouth and the esophagus. The

cerebral-pedal connective are independent

throughout their lengths. The pedal ganglia are

retained within the haemocoel of the foot, a single

commissure connects the two pedal nerves. The

cerebral ganglia are joined by a short, broad com-

missure, and each gives rise anteriorly to two labial

nerves, the optic nerve and two buccal nerves.

Zygoneury occurs between the left pleural ganglion

and the supraoesophageal ganglion which lies

against the body wall to the left of the esophagus.

The connectives between both pleurals and the

supraoesopheal ganglia are relatively long for an

advanced epiathroid condition. The suboesophageal

ganglion lies along the right side of the body wall

just below the base of the penis. Zygoneury with

the right pleural ganglion does not occur. The penis

is innervated by the suboesophageal ganglion, and

thus it is pallial in origin and not pedal as in

Pomaiias (Creek, 1951).

Type locality - Dominican Republic, Puerto

Plata Province, Loma del Puerto, Yaroa, 7(X) m

elevation. Holotype: UF 22745; collected 11

January, 1976 by Fred G. Thompson and Beverly E.

Johnson. Paratypes: UF 22746 (21), UF 22747 (114),

USNM 711132 (6); same locality as the holotype.

The type locality is in a mountain fog forest

where the prevailing northeasterly winds pass over

the crest of the mountain. The crest consists of a

rugged karsted limestone outcrop that is shrouded

by a dense forest of trees, shrubs, and ferns. A thick

carpet of moss covers practically all trees and sub-

strate. Snails were found crawling and aestivating

on bare overhanging limestone surfaces. The shells

appeared as grayish blurs against the gray

calcareous background.

SYSTEMATIC STATUS OF

THE ANNULARIIDAE

The statas of the neotropical Annulariidae has

been a matter of controversy since the group was

first separated from the Old World Pomatiasidae

(Pfeiffer. 1S5K [Licinac]; Dall, 19(ir,; Henderson

and Bartsch, 1920; Baker, 1924a, 1924b; Thiele,

1931; Torre and Bartsch, 1928, 1941; Bartsch, 1946;

Wenz, 1938; Solem, 1960, 1961; Golikov and

Starabogatov, 1975 [Licinidae]. The criterion used

by Henderson and Bartsch (1920) to separate the

Annulariidae from the Pomatiasidae is the struc-

ture of the central tooth of the radula. Arguments

against the recognition of two distinct families has

to do with the cusp variations that occur in some

neotropical species of the subfamily Cistulopsinae.

While determining the phyletic relationships of

Meganipha it is necessary to reconsider the

systematic status of the Annulariidae. Four

anatomical systems possess significant charac-

teristics relevant to this problem: (1) the radula, (2)

the male reproductive system, (3) the female

reproductive system, and (4) the nervous system.

Anatomical information on these two families is

very limited. Creek (1951) described the reproduc-

tive systems of Pomatias elegans (Miiller). Fretter

and Graham (1962: 310) described the nervous

system of P. elegans. Venmans (1959) described the

radula of P. sulcatus (Drap.) and P. militensis.

Other than various accounts of the radula, the soft

anatomy of no neotropical species has been

described previous to this report. However limited

it may be, the data currently available suggests

that the annulariids and the pomatiasids are

separable as distinct families.

RADULA

Henderson and Bartsch (1920) separated the

neotropical Annulariidae from the Old World

Pomatiasidae on the basis of the central tooth of

the radula. The neotropical species have a narrow

unicuspid central tooth in contrast to the broad

tricuspid central tooth of the Pomatiasidae. The ob-

servations by Henderson and Bartsch were slightly

in error. The central tooth of the Pomatiasidae has

five cusps, not three, and not all annulariids are

unicuspid.

Baker (1924a: 1-4) showed the two neotropical

species, Cistulops raveni (Cross) and Troschelvin-

dex illustre (Poey) [= T. candeana (Orbigny)], have

a tricuspid central tooth which bears a long slender

mesocone and a minute ecotocone on each side. He

proposed the subfamily Cistulopsinae for these

genera and suggested that they are primitive in

Vol. 92 (1)

January 31, 1978

The Nautilus 49

FIG. 5. Pomatias elegans (Miiller): SEM mictrjgraphs of mdula; Montpellier. Dept. L'Herault, France (UF 2271,9).

A. Nearly complete tmnxvers section (X 110). B. Oblique mew of central row (r) ^X 260). C. Vertical view of central

row(X 2iO). D. Vertical riew of lateral and inner marginal rows (X 260). E. Inner marginal and outer marginal teeth

(X270). F. Cusps on outer marginal teeth (X 520). Legend: r-central. \-lateral, im-inner marginal, om-outer mmyinal.

50 The Nautilus

January :«, 1978

Vol. 92 (1)

characters of the radula and operculum and are in-

termediate between the Pomatiasidae and the An-

nulariidae.

Later authors (Baker, 1924b, 1928; Solem. 1960,

1961; Thompson, 1966) continued to place the

n«)tropical species in the Pomatiasidae because of

the intermediate phylectic position that Baker

suggested for the Cistulopsinae. SEM examination

of the radulae of the genera in question reveals the

presence of several characteristics that distinguish

the neotropical Annulariidae, including the

Cistulopsinae, from the Old World Pomatiasidae.

Brief descriptions are given of the radula of

relevant genera.

POMATIASIDAE. Pomntia.^ elefimis (MiiWev)

(fig. 5). Five radulae were removed from the pre-

served specimens (UF 22749; Montpellier, Dept.

L'Herault; France). The transverse rows of teeth

overlap only slightly and give weak support to sub-

sequent rows when in use. The central tooth is very

broad and has five cusps on the cutting edge. The

three foremost cusps are nearly ecjual sized and

are flanked posteriorly by a small tubercular ec-

tocone (fig. 5, B, C-r). Tlie lateral tooth is broadly

trapezoidal in shape and bears four heavy cusps: a

small entocone, a large lanceolate mesocone, and

two ectocones (fig. 5, D-1). The inner marginal h;u^

a narrow shaft and base and bears five subequal-

sized cusps (fig. 5, D, E-im). The outer marginal is

broadly triangular in shape with a wide membrane

extending from the base of the shaft to the outer ex-

tremity of the rasping margin (fig. 5, E, F-om). The

mesad end of the rasping margin overlying the end

of the shaft bears three relatively strong, nearly

equal sized cusps which are flanked laterally by

about 42 small slender blunt filiform cusps.

Pomatias sidcatus (Drap.) and /'. mllitcNsis (Sow.)

differ from P. elegans only in the number of cusps

on the lateral teeth, not in qualitative differences

(see Venmans, 1959).

Tropidophorn hacmai^tonniw (Anton). Two

radulae were extracted from dried specimens (UF

23558; Round Island, Indian Ocean). In most essen-

tial features the teeth are like those of Pomatias

elegans, except that the outer marginal tooth has

six enlarged cusps over the end of the shaft (fig. 6.

D).

ANNULARIIDAE. The radula of Meganipha

rhcrtn n. sp. is described earlier in this paper (fig.

2). Baker (1924a, 1928) examined the radula of

about 60 neotropical sf)ecies. He noted (1924a: 2,

1928: 47-49) the nearly uniform radular structure

throughout this group and pointed out two minor

variations, one upwn which he based the subfamily

Cistulopsinae Baker, 1924 (see above) and the other

he used (1928: 48) as a basis for a new subgenus of

Licina. (Choanopomops). All of the Annulariidae

for which the radula has been described, have in

common: (1) strongly overlapping transverse rows

of teeth in contrast to the less overlapping rows in

the Pomatiasidae; (2) a narrow unicuspid or

weakly tricuspid lateral tooth in contrast to the

broad trapezoidal pentacuspid lateral of the

Pomatiasidae; (3) the outer marginal tooth has

nearly uniform-sized, narrow, sickle-shaped cusps,

in contrast to the Pomatiasidae which have several

enlarged cusps over the end of the shaft mesad to

the smaller filiform cusps; and (4) the central tooth

is relatively long and slender and has usually only

a narrow beak-like mesocone in contrast to the

broad short centrals of the Pomatiasidae, which

have a large mesocone flanked on each side by a

nearly equal-sized ectocone and a much smaller

more posteriorly located ectocone.

CISTULOPSINAE The radula of the two

genera in this subfamily are similar to other An-

nulariidae in that the transverse rows of teeth

strongly overlap, the central and lateral teeth are

relatively long and narrow with a long beak-like

central cusp, and the outer marginal teeth lack

enlarged cusps at the apex of the shaft.

Cistulops r. raveni (Crosse). Five radula were

extracted from dried specimens (USNM 393084;

Tafelberg, Curacoa). The central and lateral teeth

are tricuspid (fig. 6, A, B). Each central tooth

bears a large mesocone and a much smaller ec-

tocone on each side. Similarly the lateral tooth is

tricuspid with a large mesocone and a minute ec-

tocone and entocone.

Troschelinndex c. candeana (Orbigny). Radulae

were recovered from dried specimens (USNM

535559; outside of Havana Cemetery, Havana,

Cuba). In most particulars the teeth are similar

to Cistulops r. raveni. "Rie ectocones on the cen-

tral tooth are slightlv larger in proportion (fig. 6,

C).

Vol. 9:2 (1)

January 31, 1978

Tlie Nautilus 51

FIG. ft SEM micrographs of radula. A. Cistulops r. raveni (Crosse) fUSNM 29Sn81t) fX mi- B. same fX UO)- C.

Troschelvindex c. candeana (Orbigny) USNM 5.15559) (X i57/. D. Tropidophora haemastomum (Anton) (UF 2S558) (X m).

Legend: r-central, \-laterd. im-inner marginal. om-oiUer marginal.

52 Tlie Nautilus

January 31, 1978

Vol. 92 (1)

TTie long slender cusps on the central and

lateral teeth and the blade-like cusps on the

outer marginal tooth of the Annulariidae con-

trast strongly with the shorter blunter cusps on

the teeth of the Pomatiasidae. In addition the

broadly overlapping transverse rows of teeth in

the annulariids, which reinforce succeeding rows

during feeding, are very unlike the more

separated condition that exists in Pomatias.

These differences indicate different feeding

stratgies. The teeth of the annulariids appear to

be modified for cutting and gouging deeply into

plant tissues, whereas the teeth of the

pomatiasids appear to be modified for a scraping

action. Correlated with these interpretations is

the nature of wear on the cusps. Those in the an-

nulariids that I examined show very little wear

on the anterior teeth of the ribbon. Correspon-

ding teeth in Pomatias are conspicuously worn

and blunted.

The differences in annulariid and pomatiasid

radular structure do not in themselves constitute

characteristics sufficient for separating the two

groups as distinct families. Divergent feeding

strategies in land snail families as reflected by

radular tooth structure is a common phenomenon

(Solem, 1972, 1974). The observed differences be-

tween the annulariids and the pomatiasids may

represent divergence within a single phyletic

group below the family level. However, the

radulae of the two groups are dissimilar to the

extent that it is difficult to argue a close rela-

tionship (intra-familial) on the basis of these

organs.

FEMALE REPRODUCTIVE SYSTEM

Scant information is available on the soft

anatomy of pomatiasids or annulariids. Creek

(1951: fi()8-609) described the morphologv' and em-

bryology of the male and female reproductive

systems of Pomatias elegans (M'liller). The

reproductive systems of no annulariid have been

described prior to the account given above for

Meganipha rhecta.

Meganipha and Pomatias are very similar in

general plan. The most striking similarity among

the two genera is the elongate cleft along the

ventro-lateral margin of the capsule gland form-

ing the terminal opening of the female system. In

Pomatias this is a modification for ovulation of a

very large mucus-coated egg. By inference

Meganipha ovulates a similar and comparably

large egg.

Meganipha differs from Pomatias in the struc-

ture of the copulatory bursa and the adjacent

segment of the oviduct. In Pomatias the oviduct

enters the distal end of the bursa and continues

to the pallial oviduct in an open groove in the

floor of the bursal lumen. In Meganipha the

oviduct and copulatory bursa are interconnected

only by a narrow perforation at the end of the

bursal lumen, and the oviduct continues anterior-

ly to the pallial oviduct as a closed tube.

MALE REPRODUCTIVE SYSTEM

Meganipha and Pomatias differ in three major

aspects. In Meganipha the prostate is elongate

and lies completely anterior to the transverse

wall of the mantle cavity, the vas deferens is very

short because of the anteriad location of the pro-

state, and the penis is pallial in origin. In

Pomatias the prostate is ovate in shape and only

partially overlaps the mantle cavity so that its

posterior half lies well within the visceral cavity,

the vas deferens is considerably more elongate

because of the posteriad position of the prostate,

and the penis is pedal in origin.

NERVOUS SYSTEM

Information relating to the brain of Pomatias

elegans (Miiller) is taken from Fretter and

Graham (1962; 310). The only annulariid to be

described is Meganipha rhecta (see above). 'Riree

major features distinguish the nervous system of

Meganipha from Pomatias: (1) T^ie brain of

Meganipha is an advanced epiathroid condition.

The pleural ganglia are dorsal -lateral in position J

and are partially fused with the corresponding '

cerebral ganglia. The brain of Pomatias is not an

advanced epiathroid condition. The pleural gan-

glia are lateral in position and each is attached

to the corresponding cerebral ganglion by a slen-

der connective that is about as long as the pleu- |

ral ganglia. (2) Meganipha is zygoneurous be- '

tween the supraoesophageal and the left pleural

ganglia. In Pomatias zygoneury does not occur

Vol, 92 (1)

January 31, 1978

The Nautilus 53

between the supraoesophageal and the left pleu-

ral ganglia. (3) The penis of Meganipha is iner-

vated by the left pleural ganglion via the sub-

oesophageal nerve. The penis of Pomatias is iner-

vated by the right pedal ganglion.

SUMMARY

The data currently available support the

separation of the Annulariidae and Pomatiasidae

as distinct families. Data relating to the soft

anatomy of these two families are very limited,

except for the radula. Sufficient numbers of

radulae have been examined to characterize the

Annulariidae and the Pomatiasidae as distinct

and natural categories. The Cistulopsinae is

herein considered to be primitive in characteris-

tics of its radula and is a subfamily of the An-

nulariidae. Other data available on the reproduc-

tive systems and nervous system also support the

separation of the Annulariidae from the

Pomatiasidae. However, far more anatomical in-

formation is needed before definitive arguments

can be made relating to this question.

l^ie two families are characterized as follows:

POMATIASIDAE

1. Central tooth of radula with 5 cusps— a large

mesocone, a subequal ectocone on each side,

and a smaller ectocone posteriorly on each

side (fig. 5, B, C).

2. Lateral tooth broad, with a large mesocone, a

smaller entocone and two subequal ectocones

(fig. 5, D).

3. Cusps on outer marginal tooth dimorphic,

with 3-6 enlarged cusps over end of shaft,

contrasting strongly with more slender

filiform cusps that form a comb laterally (fig.

5, E, F).

4. Oviduct entering copulatory bursa and

continuing to albumen gland as a groove

within the bursal lumen.

5. Prostate compact and partially overlaps the

mantle cavity and the visceral coelom.

6. Penis pedal in origin, inervated by the right

pedal ganglion.

7. Pleural ganglia lateral in position and

attached to corresponding cerebral ganglia by

a slender connective.

8. Supraoesophagael ganglion not connected to

the left pleural ganglion thru zygoneury.

ANNULARIIDAE

1. (Central tooth of radula with a single long

mesocone (fig. 2, D). A small rudimentary ec-

tocone also may be present on each side

(Cistulopsinae, fig. 6, A, B, C).

2. Lateral tooth similar to central tooth; with a

single elongate cusp (fig. 2, D, E), or with an

elongate mesocone bordered by a rudimentary

ectocone and entocone (Cistulopsinae, fig. 6, A,

B,C).

3. Cusps on outer marginal tooth monomorphic,

forming a uniform comb along entire length of

rasping margin (fig. 2, B, C).

4. Copulatory bursa connected to oviduct through

a small terminal perforation. Oviduct con-

tinuing to albumen gland independently along

side of bursa.

5. Prostate elongate and lying completely an-

terior to transverse wall of mantle cavity.

6. Penis pallial in origin, inervated by the left

pleural ganglion.

7. Pleural ganglia dorsal-lateral in position and

partially fused to the corresponding cerebral

ganglia.

8. Supraoesophageal ganglion and left pleural

ganglion connected by zygoneury.

LITERATURE CITED

Baker. H. B. 1924a. New land operculates from the Dutch

Leeward Islands. TTie NautUus. 37:1-6.

Baker, H, B. 1924b. Land and freshwater moUusks of the

Dutch Leeward Islands. Occ. Pap. Miis. ZoiA. Univ. Mich.

152:1-159.

Baker, H. B, 1928, Mexican mollusks collected for Dr. Bryant

Walker in 1926, /. Occ. Pap. Mus. Zool. Univ. Mich.

ri93:l-&5.

Bartsch. P. 1946, The operculate land mollusks of the Family

Annulariidae of the Island of Hispaniola and the Bahama

Archipelago. BidL US. Nat. Mus. 192:1-264, pis. 1-38.

Creek, G. A. 1951, The reproductive system and embryology of

the snail Pumaiias elegans (Miiller). Proc. Zool. Soc Land.

121:599-640.

Dall. Wm. H, 1905, An arrangement of the American

Cyclostomatidae with a revision of the nomenclature, Proc.

Malac.Soc. Lmd. 1:208-210,

Fretter, V, and A, Graham. 1962, British Prosobmnch

Molluscs, i-xvi, 1-755. Ray Society, London.

54 The Nautilus

January 31, 1978

Vol. 92 (1)

Golikov, A. N. and Y. I. Starohogotov. 1975. Systematics of

prosobranch gastropods. Mainroloyia 15:185-232.

Henderson, .J. B. and P. Bart-sch. 192f). A classification uf the

American operculate land mollusks of the Family An-

nulariidae. Pmc. U.S. Nat. Mus. 58:49-82.

Pfeiffer. L. 18.58. Monographm himimonopomorum Viven-

tium. Suppi. l:l-viii, 1-284. Cassellis.

Solem. A. 196(). Notes on South American non-marine

Mollusca. Estr. Ann. Mus. Civico Storia Nat. Geneva

71:416432.

Solem, A. 1961. A preliminary review of the pomatiasid land

snails of Central America (Mollusca, Prosobranchia). Arch.

Moll, 90:191-213.

Solem, A. 1972. Malacological application of the Scanning

Hectron Microscope. - Radular Structure and Functioning.

Veliger. 14:327-337.

Solem, A. 1974. Patterns of radular tooth structure in car-

nivorous land snails. Veliger. 17:81-88.

Thompson, F. G. 1967. A new pomatiasid from Chiapas, Mex-

ico, ne Nautilus. 80:24-28.

Torre. C. and P. Bartsch. 1938. The Cuban operculate land

shells of the subfamily Chondropominae. Pror. i'.S. Nat.

.V/».v- 85: 19.^423; pis. 7-9.

Torree, C. and P. Bartsch. 1941. The Cuban operculate land

mollusks of the family Annulariidae. exclusive of the sub-

family Chondropominae. Pmc. U.S. Nat. Mm. 89:131-385;

pis. 9-57.

Venmans, L. A. W. E. 19.59. Notes on land and freshwater

Mollusca of southern France. Eaxteria 23:77-88.

Wenz. W. 1938-1*14. Haiulbuch der Palaozoologie. Bd. 6.

Gastropoda: Prosobranchia. 1-1639. Berlin.

TAREBIA (PROSOBRANCHIA: THIARIDAE)

IN CUBA

Morris K. Jacobson

865 Capone Street, S. E.

Palm Bay, Florida 32905

In Nautilus 89(4): 106 (October 1975) I noted the

presumably first report of the presence of the

Asian thiarid Tare bin granifera (Lamarck, 1816) in

Oriente Province, Cuba. I did not then know of a

previous mimeographed item by Miguel L. Jaume

of July 15, 1972 (Circulares Museo y Biblioteca de

Zoologi'a de La Habana pp. 1523-1525) in which the

presence of this species in extraordinary numbers

was reported in the Ri'o Cerrajo'n, 14 km from

Cupeyal. Yateras, Oriente (20°27'48"N, 75°03'4'W).

This locality, as well as the others mentioned in my

report (loc. cit.) are located generally in the SE tip

of Oriente Province, where Tarebia seems to be con-

fined at present. This would seem to suggest that

the invasion proceeded from Hispianola which lies

only 75 km to the east of Cabo Maisi'. Tarebia was

reported from there by Murry in 1971 (The

Biologist. 53(3).

ASIAN CLAM, CORBICULA. THREATENS

HAWAII

Beatrice L. Burch

Kailua, Hawaii 96734

I found living Corbirula manilenftis Philippi 1841

being sold as food in Kailua, Oahu Island, Hawaii,

on August 18, 1977, in the "Open Market" run by

the City and County of Honolulu for the small local

farmer and importer. Upon checking with the

Department of Agriculture Plant Quarantine Of-

fice, it was determined that these clams had

entered the state illegally.

Vol. 92 (1)

January 31, 1978

The Nautilus 55

The State Health Dept. Office of Food and Drug

in the Environmental Section traced their arrival

through the seller to the local importer. He had

purchased them from his son who was a Los An-

geles exporter. All the dealers involved in this

transaction were licensed only for other shell fish.

In California. Corbicida are sold only for fish bait

as their pesticide content is believed to be too great

for human consumption.

This was part of a second shipment of 100 lbs. of

clams. Both shipments were sold completely in the

open markets. While the action of the officials

cancelled the order of a third shipment of a ton of

clams, there is no way yet to see if the Corbicida in-

vasion has been stopped entirely in Hawaii at this

time.

Living Corbicula have been confiscated twice

earlier by the Quarantine Office. In those cases the

clams had been brought in from the Orient directly.

LOUISIANA CITRUS BEING

DAMAGED BY SNAILS

Dee S. Dundee

Department of Biological Sciences

University of New Orleans

New Orleans, Louisiana 70122

and E. A. Cancienne

Louisiana Cooperative Extension Service

University Station

Baton Rouge, Louisiana 70803

In the early summer of 1975, the junior author

received a request from a citrus grower in Pla-

quemines Parish, Louisiana, to recommend meth-

ods of controlling snails that were damaging fruit.

The snail problem persisted through the summer,

so again, in November 1975, he visited the citrus

grove where the damage was being done. The

satsuma fruit were ready for harvest but, due to a

depressed market, the grower was delaying the

picking. Much of the fruit was overripe and some

had begun to decompose. Snails were on almost

every fruit including some which were just begin-

ning to turn from green to yellow. The snails, some

of which were identified as Mesodon thifroidus

(Say), had been rasping through the outer peel of

the fruit down to the inner peel. The grower

pointed out that rot fungi would then attack at the

point of damage. The sour odor of the rotting fruit

apparently attracts nitidulid beetles which then

feed on the infected areas. A hole the size of the

rasped area is made in the fruit to a depth of about

12-16 mm by the beetles. As many as six of the

beetles have been found in one hole. (fig. 1).

Plaquemines Parish has, for many years, been a

commercial citrus growing area. The major crops

are navel oranges, grapefruit, and satsumas.

Heretofore, there has been no reported damage to

citrus from snails, so some doubt about the extent

of snail involvement existed (it was thought that

the beetles might be the causative agents of the

fruit damage and that the snails might be only

coincidentally involved). Thus we elected to ex-

amine the 1976 crop and run some experiments to

determine for certain that the snails and not the

beetles were the initial damagers.

In December, 1976, we went to the orchards in St.

Martin Parish (near town of Parks, LA.) where

similar snail damage had been reported in the sum-

mer of 1975. There we found the trees laden with

thousands of satsumas. The owner, Mr. Alvin

Guidry, said he was once again having the snail

problem, showed us bags of damaged fruit, and

then took us to the orchard to see for ourselves.

Underneath each tree was a depression (dug out

for aiding in watering the plants). Those depres-

sions are covered with grass and weeds which form

good cover for snails. The satsuma bottom branches

hang down into these areas. A typical tree stands

about 2 meters tall with branches from near

5(i The Nautilus

January 31, 1978

Vol. 92 (1)

FIGS, (above and below). The snatl. Bradybaena similaris

(Fenixsar I. feedimi on the citrus fruit, sntmitna.

ground level up. The depressions contained hun-

dreds of snails: Mesodon thyroidus (Say), Succinea

sp., TYiddopsis fosteri (F. C. Baker), Helicina or-

hiculata (Say), many Bradybaena ftimilaris

(Ferussac), and Polygyra texasiana (Moricand).

The air temperature was in the 5-10°C. range

after a cold frontal passage, with high wind. The

only snails active were Bradybaena, although some

of the other species were seen in the trees on leaves

and fruit. Bradybaena similaris was easily

available, so a number were collected along with

several non-damaged satsumas. Upon return home

one undamaged fruit was placed in a container

along with six Bradybaena similaris and two un-

damaged satsuma leaves. A few drops of moisture

were added and the container left overnight. Next

morning the fruit had 24 rasped areas on it (rasp-

ings as described above) and each of the leaves had

holes in them. No fruit-peel or leaf debris was

anywhere in the container, thus indicating that

both were consumed. Several additional ex-

f)eriments were done, all with similar results.

It appears evident that the citrus was being

damaged by Bradybaena similaris. We have no

reason to doubt the other grower when he says that

Mesodon thyroidiis is involved also. We do plan to

check the Plaquemine Parish orchards also and,

next season, run experiments with all of the other

species.

It is not known why or how such heavy popula-

tions of snails developed in these two orchards

located approximately 125 miles apart. The St.

Martin Parish orchard is separated from other

citrus groves, but the Plaquemines Parish grove is

surrounded by others. No report of damage has

been received from other growers.

This raises questions such as what caused the

snails to become pests and whether or not they will

continue causing damage. We plan to follow up on

these questions during the next crop-growing

season.

Vol. 92 (1)

January 31,1978

The Nautilus 57

PREDATION ON APPLE SNAIL

EGGS (POMACEA)

James A. Kushlan

U. S. National Park Service,

Everglades National Park,

Homestead, Florida 33030

ABSTRACT

Observations confirm Snyder and Snyder's (1971) conclusion that the conspicuous

eggs o/Pomacea paludosa are distastfiil to vertebrates. However certain invertebrates

eat Poniacea eggs. This complicates the strategies faced by the snail in producing con-

spicuotis eggs that may be aposematic to vertebrate but not to invertebrate predators.

Many ampullarid snails of the genus Pomacea

have colored or otherwise noncryptic eggs. The ap-

ple snail, P. paludosa (Say) lays clusters of con-

spicuous white eggs on emergent vegetation.

Snyder and Snyder (1971) found that the eggs are

distasteful in their early stages of development.

Although simple palatability tests on a wide varie-

ty of animals were inconsistant, Snyder and

Snyder found that the eggs were generally

distasteful and that some animals may learn to

avoid them. TTiey suggested that egg con-

spicuoiisness functions as warning coloration.

Orians and Janzen (1974) showed that egg

palatability is usual among animals. They cited the

Pomacea findings as one of their few examples of

toxicity among animals eggs. The occurrence of

natural predation on Pomacea eggs bears upon the

functional and strategic implications of producing

conspicuous, distasteful eggs. This present note

discusses instances of natural predation on

Pomacea eggs.

RESULTS AND DISCUSSION

The apple snail is abundant in the freshwater

wetlands of southern Florida (Kushlan 1975) and

therby provides many opportunities for observa-

tion. Many of my field observations of apple snail

eggs parallel those of Snyder and Snyder (1971).

Eggs are conspicuous but are apparently ignored

by many suitable predators. Snyder and Snyder

(1971) found that some captive vertebrates ate prof-

fered eggs, at least at a single offering, including

the White Ibis (Eudocimus albus). Apple snails

comprise over 5% of the ibis' diet in southern

Florida, but no snail eggs were found in 199 food

samples from wild birds (Kushlan and Kushlan

1975). The attraction of this species to eggs in

Snyder and Snyder's study was probably an ar-

tifact of confinement, where ibises often eat

unusual food items (Kushlan and Kushlan 1975).

Other captive vertebrates tested by the Snyders

were probably similarly affected. In my experience,

wild sunfish, expecially bluegill (Lepomis

macrochirus), wall eat offered eggs initially, but

their reaction often wanes with time.

I believe the situation in invertebrate predators

may be different than with vertebrate predators. I

have seen a coneheaded grasshopper (Neocon-

ocephabis triops) eating snail eggs. Coneheaded

grasshoppers belong to the family Tettigoniidae in

which both predatory behavior and cannabilism oc-

cur. I have not seen the grasshopf)er break open

eggs although they have strong jaws and may be

capable of doing so. It is possible that the eggs must

sustain mechanical damage prior to predation.

Regardless, the grasshopper did consume the egg

contents that were in the early, and therfore nox-

ious stage of development.

Thus it would appear that Pomacea eggs are

distasteful to vertebrates and that avoidance-

learning occurs which enables conspicuousness to

serve an aposematic function. This may not be true

for invertebrates. Several types of invertebrates

may prey on Pomacea eggs. Snyder and Snyder

(1971) reported natural predation by a milliped and

found that gyrinid beetles (Dine/nstes sp.) and

crayfish (Procambaru^ sp.) would eat eggs,

although crayfish subsequently rejected them. If a

58 The Nautilus

January 31, 1978

Vol. 92 (1)

vertebrate-invertebrate dichotomy in the effec-

tiveness of apostasis exists, it would complicate

selection pressures for avoiding egg predation. Lay-

ing eggs out of water would successfully thwart

both vertebrate and invertebrate aquatic

predators. Apostasis would reduce losses to ter-

restrial vertebrates. Protection from terrestrial in-

vertebrates may result from there being relatively

few terrestrial predatory invertebrates large

enough to eat Pomacea eggs in the marsh habitat in

which the snails live. Further information on the

extent of natural predation on Pomacea eggs may

shed light on the mechanisms used to reduce such

losses.

LITERATURE CITED

Kushlan. J. A. 197.5. Population changes of the apple snail,

Pamacea paludosa, in the southern Everglades. The Sautilus

89: 21-23.

Kushlan. .1. A. and M. S. Kushlan. 1975. Food of the White Ibis

in southern Florida. Florida Field Nat. 3: 31-38.

Orians, G. H. and D. H. Janzen. 197-4. Why are embryos so tasty?

Amfr.A'aMOS: .581-592.

Snyder. N. F R. and H. A. Snyder. 1971. Defenses of the Florida

apple snail, Pomacea paludnsa. Behairiour iO: 175-215.

WAGNER AND ABBOTTS

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LIVING MARINE

MOLLUSCS

Contents

Introduction

Historical hy C. M. Y'tmin-

The nature of molluscs hy C . M. Yonve

Classification hy C. M. Yunfie

Chitons by C. M. Yonne

The first gastropods hy C. M. Yoniie

Limpets and top shells hy C. M. Yonge

Mesogastropods hy C. M. Yoni;c

Mesogastropods — burrowers and drifters hy C. M. Ytttmc

Neogastropods^scavcngers and predators hy ( . M . Yoniie

Opisthohranch sea-snails hy T. E. Thompson

Sea-slugs hy T. E. Thompson

Origin and nature of bivalves hy C. M. Yonf^e

Evolution and adaptation of jiivalves hy C. M. Yonye

Ark shells, mussels, fan and tile shells, scallops and oysters

by C. M. Yont^e

Shallow and deep burrowing bivalves hy C. M. Yongc

Borers in rock and limber hy C. M. Yonge

Anomalous bivalves and scaphopods by C. M. Yonge

Cuttlefish, squids and octopods hy C. M. Yonge

Epilogue hy C. M. Yon^c

Selected book list

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_ Vol. 60, no.4 (.A.pril 1947). Inde.xes to new taxa (vols. 35-39) (H. B. Baker).

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" ^',^ 'Li"- ! '■^'i'-\ l»'"^'-.<^«'o'- i" P"'"""'x (Turner); Feeding by Odostomia (Allen); Life hi.storv of Campeh.na

(C7iamberlam);radulaeof Vn.s«m (Warmke),etc. "

" d"'' \Z°;u '*^*- ^^^^'- ^ "'"'^ Beriru)h,s (A. G. Smith); Studies on Melampus (Holle and Dineen); MoUusks of Salt

Kiver, K Y (Kosewater), etc.

" (Stoh^er)"etc^ ''^''"' ^^"' ^'''"^^^'^ Trunratelta (de la Torre); New Phylhmotus (Keen); Studies on mollusk p.ipulations

' m"'ii "'^^ ,"d' t; Z'^''"' ^^'- ^*"''^" ^"''''^° '^'^ *^<'"*'-' (Warmke); Mounting minute radulae (Turner) Wvoming

Mollusca (Beetle) new species, etc. • *

_ Vol. 74, no. 3 (Jan. 1961). Review of pramidellid hosts (Robertson and Orr); Mollusks of Afognak, Alaska (Everdam)-

ror-fr)«//n in Tennessee River (Smclair and Ingram), etc. i . a ,,,

" r^RnJLn°i p'ht'-' ^^"/''",''m"JT ^^'"' •^''"'^"" '"""^ ^^^'' ^'^ ^"P"'"' (B"'-*); Atlantic Rissoellidae

(Robertson); Eight new land snails (Hubricht),etc.

- ^'ol/S- no- 2 (Oct. 1961). Review of nyasira (Ockelmann); Marine Shells of Water Lsland, Virginia (Weber)- Eight

new land snails, contd.(Hubricht). etc. i- ^'>^'>^

" y^l' ^*'' Z°''l *°f'' ^*n'- N*""; C'i'-ibbean Marine Shells (McGinty); Life History of Haliotis nifescens (Carlisle)- Zinc ef-

fects on freshwater mollusks (Wurtz), etc. ^ <r,, /.iMl. ei

. Vol. 76, no. 3 (Jan. 1963). Panopea bitmncata (Robertson); Checklist Illinois Unionidae (Fechtner), etc.

" r'°'' I^,r°- ■* ,*''^''/'' ^?**^'- ^'ollusks eaten by Puerto Rican bonefish (Warmke); Four new OUvella (Burch and

Campbell); new land snails (Hubricht).

. Vol. 77, no. 1 (July 1963). Genus aivella in eastern Pacific (Burch); (hrbicula in Ohio River (Keup.f/ f(/),etc.

. Vol. 77, no. 2 (Oct. 1963). Sphaeriid clams (Thomas); western Gouiohasix (Roscoe); West African Haliotid (Talmadge).

Vol. 77, no. 4 (April 1964). Sinum and Agaronm (Burch); new unionids (Atheam); American Melampidae (Morri.son).

Vol. 78, no. 1 (July 19(>4). New Typhis (Warmke); biology ^c^trfma (Kondo; also Kraus).etc.

Vol. 78, no. 3 (Jan. 1965). New Vitrinellidae (Moore); new Latia-us (Emerson and D'Attilio), etc.

Vol. 78, na 4 (April 1965). Ecology of spiny pelec.vTxids (Nicol); Galapagos marines (Emerson and Old); land snails of

Bahamas (.Jacobson ), etc.

Vol. 79, no. 1 (July 1965) New Aspella (Emerson and D'Attilio); Hosts of Odosto,nia (Scheltema); new records of ('«««,

and ( ifpraea (Old), etc.

Vol. 79. no. 2 (Oct. 1965) New Cj/praea (Burgess); Mollusks new to South Carolina (Merrill and Petit); EJIiptio ^piiuisa

Cniomas).

Vol. 79, no. 4 (April 1966). Size of Recent Pelecypods (Nicol): Corbicula in Ijouisiana (Gunning); larvae of Lyonxia

(Qianley), etc.

Vol. 80. no. 1 (.July 1966) Life history of Achat ina (Kekauoho) (also in no. 2); Oirbirula in Texas (Metcalf); Mesodrsma

(Davis), etc.

Vol.80, no. 2 (Oct. 1966). Littorinids(Rosewater); new &>nore//a (Miller), etc.

Vol. 81. no. 1 (July 1967). New Cypraea (Burgess); new Sonorella and Pachychiltts (Thompson), etc.

Vol. 81, no. 2 (Oct. 1967). Cassis of North Carolina (Wolfe), Limnpsis (Nicol ): new Somrella (Miller), etc.

Vol. 81, no. 3 (Jan. 1968). Bermuda marine mollusks (Abbott); pteropods of .Atlantic (Chen); Partulidae (Kondo),etc.

Vol. 82, no. 2 (Oct. 1968). Introduced mollusks (Dundee and Hermann); Chromosomes in pelecypods (Menzel); new land

species, etc.

Vol. 82, no. 4 (April 19(i9). Mollu.sks new to South Carolina: II (Merrill and Petit); pteropod.s (Rao): I'nionids of

Utterback, etc.

Vol, 83. no. 1 (July VMB). Ihmax fosor (Chanley); new Oliva (Zi^Ier); Galapagos Morum (Emerson); unios; new

Caecum, etc.

Vol. 8.3, no. 3 (,Ian. 1970). New Mitridae ((]ernohorsky); new Cyniatium (Abbott); nudibranch. Doris (Franz); longevity

in snails.

Vol.84, no. 2 (Oct. 1970). Memorial number to Hertlein; new scallops (MacNeil). Hertlein'sta.xa.

Vol. 84, no. 3 (.Jan. 1971). New Ti/lMa (Habe and Koruge); new Hydrobiidae (Hubricht); ecology of Thyasira (Kanno),

etc.

Vol. X). no. 1 (July 1971). Hemidonax affinities (Bors); Fluorescence in snails (Rawls and Yater); Variation in Mudalia

shells (Branson), etc.

Vol. 8.5, no. 2 (Oct. 1971). Feeding of P'lorida Aplysis (Knikauer): ('onus piitac (Abbott); Pyramidellids (Corgan); unios,

etc.

Vol. 8.5, no. 4 (April 1972). Reef mollusks of South Carolina (Shoemaker); shell growth oi Littorina; mollusks of Lake

Birket Qarun. Egypt (Rose).

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APRIL 27, 1978

THE

NAUTILUS

Vol. 92

No. 2

A quarterly

devoted to

malacology and

the interests ot

conchologists

Founded 1889 by Henry A. Pilsbiy. Continued by H. Burrington Baker.

Editor-in-Chief: R. Tucker Abbott

EDITORIAL COMMITTEE

CONSULTING EDITORS

Dr. Arthur H. Clarke, Jr.

Division of Mollusks

National Museum of Natural History

Wa-shinjjton. D. C. 20560

Dr. William J. Clench

Curator Emeritus

Museum of Comparative Zoology

Cambridge, Mass. 02138

Dr. William K. Emerson

Department of Living Invertebrates

The American Museum of Natural History

New York, New York 1 0024

Mr. Morris K. Jacobson

Department of Living Invertebrates

The American Museum of Natural History

New York, New York 10024

Dr. Aurele La Rocque

Department of Geology

The Ohio State University

Columbus, Ohio 43210

Dr. James H. McLean

Los Angeles County Museum of Natural History

900 Exposition Boulevard

Los Angeles, California 90007

Dr. Arthur S. Merrill

Woods Hole Biological Laboratory

National Marine Fisheries Service

Woods Hole. Massachusetts 02543

Dr. Donald R. Moore

Division of Marine Geology

School of Marine and Atmospheric Science

10 Rickenbacker Causeway

Miami, Florida 33149

Dr. Joseph Rosewater

Division of Mollusks

U. S. National Museum

Washington, D.C. 20560

Dr. G. Alan Solem

Department of Invertebrates

Field Museum of Natural History

Chicago, Illinois 60605

Dr. David H. Stansbery

Museum of Zoology

The Ohio State University

Columbus, Ohio 43210

Dr. Ruth D. Turner

Department of Mollusks

Museum of Comparative Zoology

Cambridge, Mass. 02138

Dr. Gilbert L. Voss

Division of Biology

School of Marine and Atmospheric Science

10 Rickenbacker Causeway

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Dr. Charles B. Wurtz

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THE

NAUTILUS

Volume 92, Number 1 — April 27, 1978

CONTENTS

Donald R. Moore

Axel A. Olsson - An Obituary (1889-1977) 59

Walter 0. Cemohorsky

New Species of Mitridae, Costellariidae and Turridae from the Hawaiian Islands with

Notes on Mitra sphoni in the Galapagos Islands 61

Richard E. Price and Frank R. Schiebe

Measurements of Velocity from Excurrent Siphons of Freshwater Clams 67

David Nicol

Size Trends in Living Pelec\TX)ds and Gastropods with Calcareous Shells 70

William G. Lyons

Status of Eulima subcarinata Orbigny, 1842 and E. caroli Dall, 1889 (Gastropoda: Melanellidae) .... 79

Hugh M. Turner

Hcbetancyius excentricus (Morelet) (Pulmonata: Ancylidae) in Louisiana and a Report

of Septum Formation 83

William G. Lyons

Fusimis stegeri (Gastropoda: Fascioloriidae), a New Species from the Eastern Gulf of Mexico 85

Artie L. Metcalf and Richard W. Fullington

A New Fossil Ashmunella (Pulmonata: Polygyridae) from the Sierra Diablo and Hueco

Mountains, Texas 88

William K. Emerson

MoUusks with Indo-Pacific Faunal Affinities in the Eastern Pacific Ocean 91

Meetings

American Mdacologicd Union, 44th annual Western Society of Malacologists. 11th annual

meeting will be held July 16-21, 1978, on the meeting will be held June 28-July 1, 1978, at the

campus of the University of North Carolina University of Santa Clara, California. For reser-

(UNCW) in Wilmington, North Carolina. For re- vations write: Carol C. Skoglund, 3846 East

servations write: AMU, Box 394, Wrightsville Highland Avenue, Phoenix, AZ 85018.

Beach, NC 28480.

In Memoriam

Axel Adolf Olsson

19 April, 1889 - 26 October. 1977

Vol. !)2 (2)

April 27. 1978

AXEL A. OLSSON - AN OBITUARY

19 April. 1889 - 26 October. 1977

Donald R. Moore

Rosenstiel School of Marine and Atmospheric Science

University of Miami. Miami, Florida 33149

The Nautilus 59

Axel Adolf Olsson became interested in natural

history at about the age of twelve, an interest he

never lost. Bom in Gloversville, New York, he

was the son of Swedish immigrant parents, and,

as a boy, spent a year with his mother in

Sweden. He maintained close contact with rel-

atives in Sweden for the rest of his life.

.Axel worked in order to save money to go on

for a higher education. He attended the Massa-

chusetts Institute of Technology for one year,

then went to Cornell University in 1910. Here, he

promptly fell under the influence of Professor

Gilbert D. Harris, and a career in geology and in-

vertebrate paleontology was launched. Olsson

published two papers in 1912, thus beginning a

series of publications over a 61-year period.

Olsson served as laboratory assistant to Pro-

fessor Harris in his undergraduate years, then

was instructor in invertebrate paleontology while

a graduate student. During the summers, Harris

and his students explored the Atlantic coastal

plain in a small cabin cruiser, the "E^phora."

Several papers on the American Tertian,' were

published by Olsson as a result of this work.

Olsson had received his AB degree in 1913,

then began graduate studies under Professor Har-

ris. At this time he was elected to the Society of

Sigma Xi while still a student, and also won the

Goldwin Smith Fellowship in geology for the

years 1913, 1914. In 1916, Olsson and his assis-

tant, Karl Patterson Schmidt, who later became a

famous herpetologist, made an expedition to San-

to 'Domingo for Dr. Carlotta J. Maury (1874-1938)

who had been financed by the Sarah Berliner

Foundation. The purpose of the expedition was

zonal division and classification of Miocene beds

of the northern part of the island. The work was

somewhat hampered by a revolution, but the

main objective was achieved. Olsson and Schmidt

i-eturned to port by pretending to be Germans,

and, speaking this language, they were passed

through the front lines by the rebels.

Early in 1917, before finishing his dissertation.

Olsson, and several geologists from the U. S.

Geological Survey and Johns Hopkins University,

went to Central America to work in Panama and

Costa Rica. Olsson remained there about a year

and a half, working for the Sinclair Oil Company,

and made a large collection of fossils which were

sent to the U. S. National Museum. He continued

with Sinclair Oil, and was sent to Texas. Here he

mapped the subsurface geology of the Damon

Mounds Salt Dome from well drillings. This was

a pioneer work in the use of Foraminifera in oil

geology in the United States. This was followed

by work in west Texas, Oklahoma, and Loui-

siana.

Olsson returned to Cornell several times to

finish work on his Ph.D. Each time he was pulled

away for further petroleum exploration, and was

unable to complete his residence requirements.

The last time was in 1922 when he was sent to

Peru. Olsson never went back to complete his

thesis on the Miocene of Virginia, although Har-

ris published his works on Costa Rica and Peru

in Bulletins of American Paleontology.

The work in Peru was the beginning of nearly

thirty years of work in northern South America.

A considerable amount of oil was found, and oil

companies were always most generous. Olsson

was allowed much freedom of movement and un-

restricted publication on his collections of fossils.

His Tertiary and Cretaceous Paleontologj' of

northern Peru included 750 pages of text and 128

plates. South America was not his only area of

study, however. The quest for petroleum and

fossils led to the western United States, the

Canadian Rockies, and the maritime provinces of

60 Tlie Nautilus

April 27, 1978

Vol. 92 (2)

eastern Canada. In 1937 he went to New Zealand

for a two year period. In 1939 he considered an

offer to work in the near East, but for some

reason did not accept the position.

Olsson finally bought a house in Langhorne,

near Philadelphia, to house his library and collec-

tions. His widowed sister, Freda, and his brother,

Oscar, lived with him. He was also a Research

Associate of the Academy of Natural Science, and

this gave him a base where he could work. He

had been associated with H. A. Pilsbry since 1935

and they published a total of 22 papers together.

They even made an expedition to Peru during the

spring of 1948. Olsson now took an interest in the

geology and paleontology of southern Florida,

lived for a while in St. Petersburg, then pur-

chased a house in Coral Gables in 1952.

Retirement did not cause any slackening of in-

terest in the natural world. A room off the

garage became a laboratory. A spare bathroom

was set up as a darkroom. Bookcases proliferated

throughout the house. Collections, both fossil and

Recent, were stored in rough home made cabinets

in the garage, laboratory and Olsson's own

bedroom. Work on this material continued up un-

til late in 1976.

Olsson made many field trips in south Florida.

TTiese trips were usually with friends or with

professional people of various disciplines: geology,

paleontology, and biology. Discoveries were

brought to him to be met with great enthusiasm,

boundless information on fossils, and an offer to

accompany f)eople to see for himself the new

rockpit or canal bank spoil. Friends brought him

so much material that one envious paleontologist

referred to them as "Olsson's army of amateurs."

But Olsson was interested in more than fossil

specimens. To work out the admittedly confusing

stratigraphy of the Upper Cenozoic in south

Florida, he walked on the bottom of a new canal,

kept dr>' by pumps, for several miles, examined

countless rockpits, and collected on spoil banks or

outcrops over a wide area. After 1967, F. M.

Bayer and Gilbert Voss interested Olsson in the

trawled and dredged material collected by var-

ious vessels of the School of Marine Science,

University of Miami. Tliree papers were pub-

lished as a result of this work. A great deal of

work, unfortunately was never completed.

Olsson's published works included about 3700

pages, and close to 500 plates, about half of this

after his "retirement". He was a Fellow of the

Geological Society of America, a charter member

of the Paleontological Society, a very early

member of the American Association of Petrole-

um Geologists, and Past President and Life Trus-

tee of the Paleontological Research Institution.

He was awarded a Doctor of Science Degree by

the University of Miami in 1974. He was also a

Research Associate of both the Academy of

Natural Sciences of Philadelphia, and of the Na-

tional Museum of Natural History, Smithsonian

Institution.

Axel married Elsie Carleton Lawton on Sep-

tember 11, 1971, thus ending over eighty years of

bachelorhood. The Olssons traveled extensively in

Europe and in Latin America until late in 1976.

After an operation early in 1977, Axel went into

a decline, and died 26 October, the same day and

month as had his old friend, Henry Pilsbr>', some

twenty years before.

Axel Olsson never lost his interest in natural

history and the life of the past. His service to

mankind includes his work in the petroleum in-

dustry, his help and advice to one and all, and

his voluminous literature on Cenozoic Mollusca.

MAJOR WORKS PUBLISHED BY

A. A. OLSSON

1922 Vne Miocene of Northern Costa Rica with notes on its

general stratigraphic relations. Btill. Amer. Paleo. 9(.39):

l-.^OO, pis. 1-32.

1928 Contributions to the Tertiary Paleontology of Northern

Peru: Part 1. Eocene Mollusca and Brachiopoda. Bull.

Amer. Palen. 14(52): 1-1.>}. pis. 1-26.

1929 Contributions to the Tertiary Paleontology of Northern

Peru: Part 2. Upper Eocene Mollusca and Brachiopoda.

Bill. Amer. Pdeo. 15(57): 67-116. pis. 9-16.

19:50 Contributions to the Tertiary Paleontology of Northern

Peru: Part .3. Eocene Mollusca. Bull Amer. Paleo. 17(62):

1-96, pis. 1-12.

19:M Contributions to the Tertiary Paleontology of Northern

Peru: Part 4. Tlie Peruvian Oligocene. BidL Amer. Paleo.

17(63): 97-261. pis. 13-3:3.

1932 Contributions to the Tertiary Paleontology of Northern

Peru: Part 5. The Peruvian Miocene. Bull. Amer. Paleo.

19(68): 1-272, pis. 1-24.

Vol. 92 (2)

April 27. 1978

The Nautilus 61

1934 Contributions to the Paleontology of Northern Peru:

Part 6. The Cretaceous of the Amotape Region. BrtlL

Amer. Paleo. 20(69): 1-104, pis. 1-11.

1941 (with H. A. Pilsbry). A Pliocene fauna from western

Ecuador. Proc. Acad Nat. Sci Phitad. 93: 1-79. pis. 1-19.

1942 Tertiary and Quaternary fossils from the Burica Penin-

sula of Panama and Costa Rica. Btdl. Amer. Paleo.

27(106): 157 -234, pis. 14-25.

1944 Contributions to the Paleontologj' of Northern Peru:

Part 7. The Cretaceous of the Paita Region. BrdL Amer.

Paieo. 28(111): 163-270, pis. 8-24.

1945 (with H. A. Pilsbr>'). Vitrinellidae and similar

gastropods of the Panamic Province. Part 1. Proc. Acad.

Nat. Sci Ph Had. 97: 249-278, pis. 22-30.

1952 (with H. A. Pilsbrj). Vitrinellidae of the Panamic Pro-

vince. Part 2. Proc Acad. Nat. Sci. Philad. 104: 35-88,

pls.2-ia

1953 (with A. Harbison, W. G. Fargo and H. A. Pilsbry).

Pliocene MoUusca of southern Florida. Monogr. Acad.

Nat. Sci Philad. 8: M57, pis. 1-65.

19.56 Studies on the genus Olivella. Proc. Acad. Nut. Sci

Philad 108: 155-225, pis. 8-16.

19.58 (with T. L. McGinty). Recent marine mollusks from the

Caribbean coast of Panama with the description of some

new genera and species. BiUL Amer. Paleo. 39(177): 5-58,

pis. 1-.5.

1961 Panamic— Pacific Pelecypoda. Paleontological Research

Institution, Ithaca, New York: 1-.574, pis. 1-86.

1964 Neogene mollusks from northwestern Ecuador. Paleon-

tological Research Institution, Ithaca. New York: 1-256,

38 pis.

1964 (with R. E. Petit). Some Neogene Mollusca from Florida

and the Carolinas. Bull. Amer. Paleo. 47(217): .509-574,

pis. 77-83.

1967 Some Tertiar>' mollusks from south Florida and the

Caribbean. Paleontological Research Institution, Ithaca,

New York: 1-66. pis. 1-9.

1971 Mollusks from the Gulf of Panama collected by RA^

PILLSBURY, 1967. Bidl. Mar. Sci 21(1): 35-92, 103

figs.

NEW SPECIES OF MITRIDAE, COSTELLARIIDAE AND TURRIDAE FROM THE

HAWAIIAN ISLANDS WITH NOTES ON MITRA SPHONI

IN THE GALAPAGOS ISLANDS

Walter 0. Cemohorsky

Auckland Institute and Museum

Private Bag Auckland, New Zealand

ABSTRACT

Two new species of Costellariidae, ie. Vexillum (Costellaria) wolfei sp. nov.,

and V. (C.) adamsianum sp. nov., a new mitrid Neocancilla kayae sp. nov., and a

new turrid Mitrolumna salisburyi sp. nov., are described from deeper water in

the Hawaiian Islands. The previously reported occurrence of Mitra sphoni Sha'iky

& Campbell, in the Galapagos Islands is here confirmed and documented by an

illustrated specimen; the species is re-assigned to Mitra (Nebularia).

Family Mitridae

Neocancilla kayae new species

(Figs. 1.2)

Description— ^e\\ moderately small, 8.0 - 14.0

mm in length, elongate-ovate and stumpier than

other species of the genus, width about 40-43% of

length, protoconch incomplete but multispiral

and consisting of 3+ smooth, glassy embryonic

whorls, teleoconch consisting of 5-6 almost flat-

sided, mature whorls, sutures deeply incised. First

1-3 post-embryonic whorls sculptured with deep

vertical and horizontal grooves which produce 3

spiral rows of laterally or vertically elongated

nodules, fourth whorl with 4 rows of nodules,

penultimate whorl with 5 rows and body whorl

with 11-14 rows of nodules and 8-9 smoother and

oblique cords basally; on the last two whorls the

nodules are regular, elevated and round, close-set

and sometimes touching each other and connected

to each other both laterally and vertically; the

62 The Nautilus

April

1978

Vol. 92 (2)

FIGS. 1, 2. Neocancilla kayae new species. 1. Haloti/pe. length s.

2. Panitijpe. Ipntjth 11.5 mm.

interspaces are deep and the nodules are regular-

ly aligned in both directions. Aperture slightly

longer than the spire, narrow and smooth within,

outer lip convex, columella with 4 strong, oblique

folds which decrease in size anteriorly; si phonal

canal straight, siphonal notch deep. White in col-

our, ornamented with reddish brown streaks

which are saturated in blotches, occasional nodule

coloured reddish brown, aperture creamy-white

and with an indication of 2 orange-brown zones.

Measurements (mm)

A/aima/-HOLOTYPE and type locality:

Pokai Bav, Oahu, Hawaiian Ids., 60-70 fathoms;

AIM/TM-ia55. PARATYPES: No. 1-Pokai Bay,

Oahu, H.I., 100 fathoms; AIM. No.'s 2-3-same

locality as No. 1; coll. R. Salisbury.

/?a«</p— Apparently endemic to the Hawaiian

Islands, 60-100 fathoms, in mud and sand or sand

and coralline algae.

Remarks— This species differs from all other

Neocancilla species in the deeply incised sutures

and regular rows of round, close-set nodules. A^.

pnpilio (Link), has a complicated sculpture of

alternating larger and smaller, low fillets which

appear stepped in profile and numerous, shallow

longitudinal grooves and filleted narrow spiral

cords. The sculpture in A^. clathrus (Gmelin) and

A^. arenacea (Dunker) is of similar style to A^.

papilio and also consists of alternating low,

quadrate fillets with laterally elongate fillets in

between, and numerous longitudinal grooves.

The new species is only tentatively assigned to

Neocancilla imtil the radula is examined. Tlie

species is named for Dr. Alison Kay. University

of Hawaii, for her valuable research contributions

to Hawaiian and Polynesian malacology.

Mitra (Nebularia) sphoni Shasky

& Campbell. 1964

(Fig. 3)

\9M \fitya (Strigafella) xphoni Shasky & Campbell. TTie

Veliger, vol. 7. no. Z p. 118. pi. 22. figs. 13. 14.

1971 Mitra (Strigatella) sphoni Shasky & Campbell. Keen,

Sea Shells Tropical west America, ed. 2. p. 642. fig. 1428.

197fi Siihcancilla sph<mi (Shasky & Campbell). Sphon, The

Nautilus, vol. 90. no. 2. p. (3.

1976 Mitra (Nebularia) sphoni Shasky & Campbell. Cernohor-

sky. Indo-Pacific Moll. vol. 3, no. 17, p. 4,52 pi. 401.

Vol. 92 (2

April 27. 1978

The Nautilus 63

Sphon (1976) reported a range-extension for

this species, (which originally has been described

from Guaymas, Mexico) to the Galapagos Islands.

This range extension is confirmed by another

specimen dredged in 40 metres by the "Foxtrot"

Expedition between Isla Barbara and Isla Santa

Cruz, Galapagos, in May 1974. This Galapagan

specimen has somewhat deeper longitudinal

troughs which give rise to weak axial folds on the

body whorl, and the interspaces of the spiral

cords are obsoletely Urate.

We agree with Sphon (op. eit.) that the original

placement of the species in the mitrid subgenus

Strigatella Swainson, was inappropriate, since

StrigatpUa species show a consistent feature of a

posteriorly thickened outer lip, which frequently

takes the form of a blunt denticle. However,

Sphon 's placement of sphoni in the genus Sub-

cancilla Olsson & Harbison, is equally inap-

propriate since sphoni lacks the characteristic

features of that genus. Mitra sphoni is closely

related to the west American M. crenata

Broderip, and is conchologically extremely

similar to such Indo-Pacific Nebidaria species as

M. proscissa Reeve, M. fraga Quoy & Gaimard, M.

rnbritincta Reeve, and several others whose

radulae are known to be of the Mitra type. It is

my opinion that once the radulae of M. crenata

and M. sphoni are examined, they will prove to

be of the mitrine type.

Family Costellariidae Macdonald, 1860

Tlie chronologically prior family-group name

Costellariidae Macdonald, 1860, will have to

replace Vexillidae Thiele, 1929. For further

discussion on this subject see Cernohorsky (1976).

Vexillum (Costellaria) wolfei new species

(Figs. 4. 5)

Description— Shell very small, 5.0-10.0 mm in

length, elongate-ovate, width 38-42% of length,

shining, protoconch conical-multispiral, consisting

FIG. 3. Mitra (Nebularia) sphoni Shasky & OimpbeH:

xperimenfmm the GalapagoK Ids., length 25.6 mm.

FKiS. 1. .5. Ve.xilluni (Costellaria) wolfei new species. 4.

Hiilotj/pe. length l!.J mm. 5 Pandifpe. length 6.6 mm.

64 The Nautilus

April 27, 1978

Vol. 92 (2)

of 3'/4-3V4 glassy, embryonic whorls which are ei-

ther straight or tilted, teleoconch consisting of

5-6 convex, mature whorls. Sculptured with slen-

der and thin axial ribs which produce a row of

sutural nodules and number from 12-17 on the

penultimate and 14-17 on the body whorls; spiral

sculpture consists of narrow, flattish spiral cords

which only ascend the wall of the ribs rendering

these imperceptibly nodulose; spiral threads

number from 5-7 on the penultimate and from

10-12 on the body whorl, base of shell with 3 or 4

nodulose cords followed by 3 or 4 smoother cords.

Aperture slightly shorter than the spire, height

42-47% of length, lirate within, outer lip convex,

columella only weakly calloused and with 3 or 4

prominent, oblique folds which decrease in size

anteriorly. Base colour white, frequently with a

translucent golden sheen, 4 spiral cords anterior-

ly to the sutures and 4 cords at the base of the

body whorl lined with reddish brown and giving

the impression of a broad central band, inter-

spaces of sutural nodules usually spotted with

reddish brown in mature individuals; aperture

white and lined with reddish brovm; columella

white.

Measurements (mm)

A/a<eno/-HOLOTYPE: Pokai Bay, Oahu,

Hawaiian Ids., 60-70 fathoms; AIM/TM-1348.

PARATYPES: No. 1-same data as the holotype;

DMNH 112103. No. 2.-same data as the

holotype: BPBM. No. 3-Keehi Lagoon, Oahu, H.I.;

100 fathoms; Salisbury coll. Nos. 4-24— same data

as the holotype; AIM and other institutions and

collections.

/^an^p— Apparently endemic to the Hawaiian

Islands, ttO-KH) fathoms.

Remarks— V. (C.) wolfei can be compared with

the moderately common intertidal and subtidal

Indo-Pacific species, V. (C.) amanda (Reeve, 1845),

but the latter species is somewhat larger, con-

siderably more solid with a duller surface and

more slender sutural nodules which are usually

the same width as the ribs, and more numerous,

finer and thinner spiral threads. V. (C.) amanda

has a continuous dark-brown sutural band on the

spire whorls and 2 or 3 dark-brown bands on the

body whorl, and lacks the reddish brown-lined

cords, as well as the translucent sheen of V. (C.)

wolfei.

This new species is named for Mr. C. S. Wolfe,

Honolulu, in appreciation for his services to the

Hawaiian Malacological Society, Junior Shell

Club, and other Hawaiian malacological projects

Vexillum (Costellaria) adamsianum new species

(Figs. 6-9)

1963 "Mitra agria Dail MS", J. Gate, Tlie Veliger, vol. 6, no.

1, p. .36. pi. 7. fig. 32 (nomen nudum)- placed in synonymy

of Vexillum xenium Pilsbry. 1921.

Description— SheW moderately small, 8.0-17.0

mm in length, elongate to elongate-ovate, some

individuals broader than others, width 34-42% of

length, protoconch conical-multispiral, consisting

of 3' 2 glassy, white embryonic whorls, teleoconch

consisting of 5'/2-7Vi slightly convex mature

whorls which are distinctly angulate at the

sutures. Sculptured with angulate and usually

straight axial ribs which number from 13-17 on

the penultimate and from 13-21 on the body

whorl; spiral sculpture consists of distinct, low

spiral cords which ascend the walls of the axial

ribs and usually notch their summits, cords

number from 5-7 on the penultimate and from

8-12 on the body whorl, siphonal fasciole with 2

or 3 nodulose, oblique cords. Aperture slightly

shorter or longer than the spire, 44-55% of

length. Urate within, outer lip weakly convex, col-

umella not calloused and with 4 or 5 (usually 4)

oblique folds which decrease in size anteriorly.

Variable in colour but usually white and sparsely

or densely ornamented with dark reddish brown

or purple-brown areas of varying intensity and

usually appearing as quadrate or rectangular

blotches arranged in two broad bands on the body

whorl and a single band on the spire whorls; the

white central band is with or without an inter-

rupted reddish brown sprial line, aperture rose-

purple to violet -purple.

Vol. 92 (2)

April 27, 1978

The Nautilus &5

FIGS. 6-9. Vexillum (Costellaria) adamsianum new species. Keehi Lagoon, Oahu, Hawaiian Ids. 6. Holotype. length 1S.7

mm. 7. Paratype. length U.j mm. 8. Paratifiie. length 16.8 mm. 9. Paratype—subadidt. length 9.0 mm.

Measurements (mm)

Ma/e?-(a/-HOLOTYPE: Keehi Lagoon, Oahu,

Hawaiian Islands, 50 fathoms; AIM/TM-1354.

PARATYPES: No. 1-same data as the holotype;

coll. A. Adams. No. 2-St. 3846, south coast of

Molokai Id., H.I., 60-64 fathoms at 71.5° F;

USNM 173197. No. 3-reef near Honolulu, Oahu,

H.I.; USNM 338182. No. 4-same data as the

holotype: DMNH. Paratypes No. 5-14 from Keehi

Lagoon, Oahu, H.I., 125 fathoms, from Makaha

Beach, Oahu, H.I., 40 fathoms, and from Pokai

Bay, Oahu, H.I., 40-100 fathoms, are in the B. P.

Bishop Museum, Honolulu, AIM, coll. A. Adams

and coll. R. Salisbury. Specimens from Hitiaa,

Tahiti, French Polynesia, are in coll. J. Trondle

and AIM.

i?a«3e— Various stations in the Hawaiian

Islands, 40-125 fathoms, in Pvnna beds or sand

and coral-rubble. Also occurs at Hitiaa, Tahiti,

10-12 m.

Remarks— Ihe first three specimens of the new

species were taken many years ago by the U. S.

Fish Commission in the Hawaiian Islands and a

single specimen was found by D. Thaanum on a

reef near Honolulu. The late W. H. Dall marked

these specimens "Mitra agria Dall" on labels in

the National Museum of Natural History, Wash-

ington, clearly recognizing the taxon as new to

science. The name has never been published and

remained a manuscript name. J. Gate (1963) in a

revision of Ball's Hawaiian Mitridae, published

the name "Mitra agria" as a nomen nudum, and

considered the species to be a juvenile stage of

Vexillum (Costellaria) xenium Pilsbry, 1921.

Dall's specimens, however, are conspecific with V.

(C.) adamsianum and have been included in the

type-series of this species.

V. (C.) adamsianum is superficially similar to

V. (C.) wolfei but differs in its larger size,

distinctly angulate whorls, coarser sculpture, col-

our, and absence of a sutural row or nodules and

the translucent golden sheen. In some younger

specimens of V. (C.) adamsianum the axial ribs

protrude slightly above the suture and giving

them a hooked appearance.

The species is named for Mr. Andrew C.

Adams, Aiea, Hawaii, in recognition of his sub-

66 The Nautilus

April 27. 1978

Vol. 92 (2)

tidal dredging efforts in the Hawaiian Islands

which brought to light specimens of the new

species.

After the manuscript and plates were com-

pleted, we have received 2 specimens of V. (C.)

adamsianum from Hitiaa, Tahiti, which were col-

lected by Mr. J. Trondle from Papeete. Although

collected in only 10-12 metres, the specimens are

undoubtedly V. (C.) adamsianum.

Family Turridae

Subfamily Mitromorphinae Casey, 1904

Mitrolumna salisburyi new species

(Figs. 10-12)

Description— '&\\q\\ minute 3.0-4.0 mm in

length, ovate-biconic, width 47-50% of length,

shining, sutures barely distinguishable and only

indicated by a slightly deeper sutural trough on

which are superimposed short axial riblets con-

necting the two sutural rows of nodules: pro-

toconch conical-multispiral, consisting of 3' 2

smooth, glossy , golden-brown embryonic whorls,

teleoconch consisting of 4'/4-4'/2 mature convex

whorls. Sculpture on first one-half of the post-

embryonic whorls consists of 3 or 4 spiral

rows of small, regular nodules, subsequent whorls

with 3 rows of nodules, penultimate whorl with 4

rows of nodules, the two central rows partly

fused together and forming short axial ribs which

number from 24-26, body whorl with 7 or 8 spiral

rows of moderately large nodules, followed by 6

or 7 oblique cords which commence in line with

the first columellar fold, first 3 or 4 posterior

cords nodulose, last 3 cords fairly smooth. Aper-

ture about the same height as the spire, narrow,

shortly Urate within, constricted posteriorly by a

prominent callosity which sometimes consists of

two fused denticles, turrid sinus moderately dis-

tinct but not deep, columella centrally with a

"V"-shaped fissure which produces 2 prominently

swollen cords, posterior cord slightly larger than

anterior one, siphonal canal spout-shaped. Base

colour orange-brown, both posterior and anterior

row of sutural nodules rosy-mauve, nodules an-

teriorly to the body whorl suture white, followed

by a rosy -mauve peripheral band extending over

2 rows of nodules and another rosy-mauve basal

band extending over the first 3 oblique cords on

the siphonal fasciole; aperture rosy-mauve, callus

on outer lip pale rose or whitish.

Measurements (mm)

length

4.0

width

2.0

FKIS. 10-12. Mitrolumna salisburyi neiv sixcieK. 10.,

Hnlntype, length U.0 mm. 12. Parol j/pe. length i.2 mm.

11

Holotype (AIM/rM-m9)

Paratypes:

No. 1 (AIM) 4.2 2.0

No. 2 (DMNH 112101) 3.9 1.9

Mi<ena/-HOLOTYPE and type locality: Maile

Point, Oahu, Hawaiian Ids., at base of cliff, 32

fathoms {leg. R. Salisbury, 22-V-1976);

AIM/TM-1349. PARATYPES: No. 1-same data as

the holotype; AIM. No. 2— same data as the holo-

type; DMNH 112101. No.'s 3-5-in coll. R. Salis-

bury, Honolulu, from the type-locality.

Range— Known only from Maile Point, Oahu,

Hawaiian Ids., in 32 fathoms.

Kemarks— This is the second known species of

Mitrolumna from the tropical Indo-West Pacific,

the other being M. stepheni (Melvill & Standen,

1897). The Indo-Pacific Mitromorpha lachryma

(Reeve, 1845) and M. (Lovellonaj atramentosa

(Reeve, 1849), and the Hawaiian M. peaseana

Finlay, 1927 (= Conus jusiformis Pease, 1861 =

Vol. 92 (2)

April 27. 1978

The Nautilus 67

C. parrm Pease, 1868, both homonyms), also

belong to the subfamily Mitromorphinae, but

should be assigned to Mitromorpha Carpenter,

since all 3 species lack the biplicate columella

which is a characteristic feature of Mitrolumnn.

Mitrolumna stepheni (M. & St.), is similar to

M. mli)iburi/i. but is more elongate, the axial ribs

are more angulate, wider-spaced and better

developed, and the axial sculpture terminates on

the body whorl at the periphery where it is

replaced by flatfish, smooth spiral cords which

commence in line with the sinus. In M. salisburi/i

the whole body whorl is nodulose with the excep-

tion of the last 3 anterior cords, and the oblique

spiral cords commence in line with the first col-

umellar fold. There are only 15-16 axial riblets

on the penultimate whorl in M. stepheni but

24-26 in M. salisburyi. M. stepheni is coloured

quite differently, being white to yellowish -fawn,

ornamented with a single row of wide-spaced,

dark brown spots on the penultimate whorl

suture, and the dorsal side of the body whorl has

a large, dilacerated, dark orange-brown blotch

which intrudes partly between the interspaces of

the axial ribs. M. stepheni also has 3''2-4 conical

embryonic whorls, but they are milky-white in

colour and not glassy golden-brown.

Although other species of Mitrolumna have

l'2-2'2 dome-shaped embryonic whorls, M.

stepheni and M. snUshurj/i have a protoconch of

3' 2-4 conical embryonic whorls, and the Ga-

lap^an M. keenae Emerson & Radwin, 1969, a

protoconch of 3''4 whorls. The same diversity of

protoconch features exists in other genera of Tur-

ridae, and a further subdivision of Mitrolumna

on this basis alone is not warranted.

The new species is named for Mr. R. Salisbury,

Honolulu, in recognition for his extensive field-

work in the Pacific, resulting in the discovery of

several new species.

ACKNOWLEDGMENTS

I would like to express my thanks to Dr. H. A.

Rehder, National Museum of Natural History,

Washington, for the loan of Dall's niitrid

specimens, and to Mr. R. Salisbury, Honolulu, Mr.

B. Parkinson, Rabaul, and Mr. J. Trondle,

Papeete, Tahiti, for the loan of specimens.

LITERATURE CITED

Gate, J. M. 1963. Revision of Dall's Hawaiian niitrids with

descriptions of three new species. TJic Veliyer 6(1): 23-43, 4

pits., map.

Cernohorsky, W. 0. 1976. The taxonomy of some Indo-Pacific

Mollusea Part 4. With descriptions of new taxa and

remarks on Nassariiis coppingeri (Smith J. Rec. Auckland

InM. Ate. 13: 111-129. 43 text figs.

Sphon. G. G. 1976. Tlie Mitridae of the Galapagos Islands. TTie

Nautilus 90(2): 63-64, text figs.

MEASUREMENTS OF VELOCITY FROM EXCURRENT SIPHONS OF

FRESHWATER CLAMS'

Richard E. Price and Frank R. Schiebe^

ABSTRACT

//( the stiuly of trace metal accumulation and food web relationships of plankton

and clams, it is important to know the volume of water passitig through a clam.

Water velocities from the excurrent siphon of Anodonta sp. were measured using a

hot-film anemometer and hydraulic procedures. Clam siphons were measured and

volumes of water pumped were calculated. Pumping velocities for indimduals,

regardless of size, were nearly constant. The volume of water passing through

clnms iras correlated with their sizes.

' Contribution from the Department of Biology, University of

Mississippi in cooperation with the U. S. Sedimentation

Laboratory, Agricultural Research Service, Oxford, Mississip-

pi 3865.5.

' Graduate Student, University of Mississippi, and Research

Hydraulic Engineer, U. S. Sedimentation Laboratory, respec-

tively.

Vol. 92 (2)

April 27, 1978

The Nautilus 68

In studying the feeding habits of freshwater

clams {Anodfinta sp.), the quantity of water pass-

ing over the gills should be known. Water is

pumped in by ciliary action and passed across the

gill filaments. Plankton suspended in the water is

trapped on the gills to be used as food (Hart and

Fuller, 1974). Allen (1914 and 1921) stated that

"food particles are carried into the mantle

chamber by water currents induced by cilia on

the gills and are intercepted on the surface of the

gills by cilia there," and that "lake mussel con-

tinues feeding at nearly all times." This would

suggest that a constant stream of water is being

siphoned by the clam and passed over the gills.

Little is known about the velocity or the quantity

of water involved in the feeding processes.

Knowledge of the quantity of water being filtered

and the concentration of food particles would

give information relative to food delivery to the

organism. To obtain this knowledge, a method

was developed for measuring the velocity of

water from the excurrent siphons of clams.

MATERIALS AND METHODS

The required instrumentation should meet

several criteria: the measurement should be

taken as near as possible to the siphon, if not in-

side it; the device should be sensitive and ac-

curate enough to detect the very low currents

produced by the clams; and it should not disturb

the clam's natural functions. A hot-film

anemometer meets these criteria.

The basic principles of the hot-film ane-

mometers were explained by King (1914). He

described the manner by which heat energy is

transferred away from a heated cylinder posi-

tioned normal to a flow. The amount of heat lost

from the cylinder is related to flow velocity.

These principles have been applied in commercial

developments in recent years, and practical in-

struments capable of measuring very low velo-

cities with small sensors are available (Lii

B;irbera and Vogel, 1976).

Hot-film probes can be obtained to fit inside

the excurrent siphon with little or no adverse ef-

fect on the clam and yet are accurate enough to

monitor the velocity of water being ejected. The

probe used in these experiments was a Thermo-

Systems 1210 cylinder', 1 mm long and 0.05 mm

in diameter. The probe was positioned with the

axis of the cylinder normal to the flow, and was

used in conjunction with a Disa No. 55D00 ane-

mometer system.

The hot -film anemometer was calibrated using a

small orifice facility wherein the water velocity

through the orifice is related to the head difference

across the orifice. A curve for velocity vs. voltage

was obtained.

Four clams were obtained from Lake Washing-

ton near Greenville, Mississippi, and placed in a

;^-liter aquarium containing sand. Di.stilled water

spiked with lake water was used to simulate

natural chemical conditions. Clams were allowed

time to adjust and to position themselves for

feeding. Water temperature during the exiJeriment

was held constant at 21° C.

Measurements of the flow into the incurrent

siphon were attempted, but due to difficulties

associated with the flow field into an opening,

they were discontinued in favor of measuring the

more uniform jet-like flow of the excurrent

siphon. The probe was positioned 2 mm or less

from the excuiTent siphon of the clams.

The siphon length and width and shell dimen-

sions of each clam was measured with a caliper.

The cross-sectional area of each siphon was ap-

proximated by assuming the opening was ellipti-

cal. The volume of the shell was approximated by

assuming an ellipsoid v«th axis lengths equiva-

lent to the shell dimensions and calculating its

volume.

RESULTS AND DISCUSSION

Pumping velocities for all the specimens were

nearly constant, regardless of shell size (see Table

1). That no change in the velocity was detectable

when the probe was repositioned within the si-

phon fiirther attested to the uniformity of the

flow. Thus, the mechanism by which water is

moved appears to be independent of physical size.

' Names of products are given for information purposes only

and do not constitute an endorsement or preferential use by

the U. S. Department of Agriculture or the University of

Mississippi.

69 Tlie Nautilus

April 27, 1978

Vol. 92 (2)

TABLE 1. Physical Dvmensiuns, Excurrent Velocity and Discharge of Clajns.

Differences in the volumes of water circulated by

individuals are thus related to siphon size and

gill area.

Tolstikova and Orlov (1972) have shown by sta-

tistical methods that a fixed relationship exists

between shell length, height, and convexity. This

relationship differs in different genera and spe-

cies. If the product of shell length, height, and

width is proportional to the clam volume, then it

also may be proportional to the gill area. This in-

dex figure could be used to determine discharge

5r

o

UJ

s

liJ

<

X

o

VI

100 200 300 400

COMPUTED SHELL VOLUME (CM')

500

FIG. 1. Relationship betji'een volume o/ Anodonta clam shell

and excurrent discharge.

among individuals of a species. A curve showing

the relationship of clam volume to discharge is

presented in Fig. 1. Although there were only 4

measurements, they do indicate a definite trend.

CONCLUSIONS

1. The hot-film anemometer is a useful and ac-

curate means of measuring the velocity of

water pumped from excurrent siphons of

clams.

2. Pumping velocities for individual clams was

nearly constant, regardless of their size.

3. The volume of water pumped by clams is

related to their shell size.

LITERATURE CITED

Allen. W. R. 1914. The food and feeding habits of freshwater

mussels, fto/. Bull. 27: 127-147.

1921. Studies of the food relations of certain

Unionidae. Biol. Bidl 40: 210-241.

Hart, C. W., Jr. and S. L. H. Fuller. 1974. Clams and mussels.

215-273. In: Hart, C. W., Jr. and S. L. H. Fuller (eds.).

Pollution Ecology of Freshwater Invertebrates. Academic

Press. New York.

King. L. V. 1914. On the convection of heat from small

cylinders in a stream of fluid: Determination of the convec-

tion constants of small platinum wires with applications to

hot-wire anemometry. Proc. Roy. Soc. (Limdon). 214A(14):

373.

La Barbera. M. and S. Vogel. 1976. An inexpensive thermistor

flowmeter for aquatic biology. Limnol Oceanogr. 21:

7.50-7.56.

Tolstikova. N. V. and V. A. Orlov. 1972. A study of variability

of freshwater bivalve molluscs with computers. Zool. Zli.

59(7): 969-974.

70 The Nautilus

April

197S

Vol. 92 (2)

SIZE TRB]NDS IN

LIVING PELECYPODS AND GASTROPODS

WITH CALCAREOUS SHELLS

David Nicol

Department of Geology

University of Florida

Gainesville," Florida 32611

ABSTRACT

/ recorded the shell size of each living moliuacan species having a calcareous

shell in at leant 10 faunuii of each (f the follairing groups: marine, freshwater,

ami land gastropods and marine and fresh-water pelecypods. In marine pelecifpods

there is a higher percentage of large-sized species in warm water than in cold

water; and in the Arctic, east Greenland. Antarctic, and deep-sea faunas, no

species of pelecypod attains a size of more than 100 mm. There is a larger

number, but not percentage, of large-sized marine gastropods in warm ivater,

and the range of size is greater in warm water than it is in cold water. The much

more diverse marine gastropods do not have nearly so marked a trend toward

larger size in ivarm water as do the marine pelecypods. Both the marine

pelecypods and gastropods have an uncommonly high percentage of small-sized

species (10 mm or less) in the Antarctie region. The fresh unter pelecypods have a

strong trend toward a higher percentage of large -sized species in warm ivater. and

only the pisidiids. which are of small size, are found in regions of coldest uater, as

for example, Iceland and Patagonia. JTie freshwater gastropods also have a strong

trend toward a higher percentage of large-sized species in unrm unter. One

regional anomaly is that New Zealand has an exceptionally high percentage of

small-sized species of both freshunter and land gastropods. The land gastropods

show a trend toward a higher percentage of large-sized species in the lower

latitudes, but it is not so pronounced as it is in the freshivater pelecypods and

gastropods. The largest species of land gastropods are commonly confined to wann

and moist regions.

INTRODUCTION

I recorded the size of each species of living

pelecypod and gastropod having a calcareous shell

in 10 or more regional faunas in each of the follow-

ing groups: marine and freshwater pelecypods and

marine, freshwater, and land gastropods. Little

analysis of this kind has been done on in-

vertebrates, although Be' (1968, p. 881) noted that

tropical and subtropical species of planktonic

Foraminiferida were generally larger than those

species living in cold water, and Nicol and Martin

(1976) showed that the largest calcareous benthic

Foraminiferida live in warm water and the largest

agglutinated Foraminiferida live in cold water.

Nicol (1966) observed that a higher percentage of

large-sized species of marine pelecypods live in

warm water.

This type of size analysis was performed by

Lindsey on poikilotherm vertebrates (1966). He

recorded the size of each species from regional

monographs and arranged them into size classes.

Lindsey found a clear trend toward a higher

Vol. 92 (2)

April

1978

Tlie Nautilus 71

percentage of large-sized species of freshwater fish

in the higher latitudes or colder water. He found

the same trend occurring, to a somewhat less ex-

tent, in shallow-water marine fish. Lindsey noted a

geographic anomaly: in the Sea of Okhotsk the

species of fish were of uncommonly small size, con-

sidering the coldness of the wat«r in that region.

Surprisingly enough, the trend toward a higher

percentage of large-sized species in higher latitudes

was even more marked in deep-sea fish than it was

in shallow-water marine fish, but Lindsey did not

specify what he meant by deep sea. The trend

toward a higher percentage of large-sized species in

colder climates is also well marked in all

amphibians— frogs, toads, and salamanders. With

the exception of the Boidae, which are largely

restricted to the tropics, the snakes show a slight

trend toward larger size in the higher latitudes.

There is no correlation between size and latitude in

either the lizards or non-marine turtles. It is in-

teresting to note the latitudinal differences in size

trends in these poikilotherm vertebrate groups

from very marked, through slight, to none at all,

because these differences also occur in some living

invertebrate groups with calcareous shells or tests.

It will also be noted that regional anomalies in size

distributions occur in calcareous-shelled mollusks.

SIZE ANALYSIS

In marine pelecypods there is a higher percen-

tage of large-sized species in warm water than in

cold water, the reverse of what Lindsey found in

fish and amphibians (Fig. 1). In the deep-sea

pelecypod fauna (2,000 m or more in depth), and

also in the east Greenland and Antarctic pelecypod

faunas, no species attains a size greater than 100

mm.

The largest living species of pelecypod is the well

known Tridacna gigas (Linne), which attains a

length of 1,370 mm. The giant clam is confined to

the warmest water of the western Pacific and

eastern Indian Oceans (Rosewater, 1965). This

distribution coincides with the region of maximum

diversity of living hermatypic corals (Stehli and

Wells, 1971; Newell, 1971). The Tridacnidae are all

large; the smallest species reaches a size of 200 mm,

and one other species of Tridacna attains a size of

513 mm. All species of living Tridacnidae live in the

MARINE

PELECYPODS GASTROPODS

60 1%

Sl20j

60

;40

i

; 20^

2%

(I)

li^n-e^-i

Z

3 40

Z

60

<

g40

in

= 20

%

60i

O

O40

o

a:

2 20

48%

%

10% I-

13%

goo

CI

o

520

( 10 I 10 I - 30 I - >60 0

SIZE MM

(M = NUMBER OF SPECIES IN EACH

FAUNA THAT ATTAIN A SIZE MOOO MM.

FIG. 1. Frequency hittngrams showing the percentages of

species in four size claxses in cold- and ivarm-vxiter marine

pelecypod and gastropod faunas.

lower latitudes of the Indian and western Pacific

Oceans.

The smallest pelecypods are about 1.0 mm in size,

and these tiny bivalves may live in either cold or

warm water. The Antarctic region has an uncom-

monly high percentage (61%) of species that are no

larger than 10 mm. The east Greenland fauna, in

contrast, has only 29% of its sf)ecies no larger than

10 mm. The Antarctic pelecypod fauna has many

species of the families Philobryidae and Cyamiidae

(Nicol, 1967b). Species of these two families rarely

attain a maximum size of more than 10 mm. These

two families have many species in the Southern

Hemisphere, and this partially explains why the

South Australian and New Zealand pelecypod

faunas have a surprisingly high percentage of

species that never attain a size of more than 10 mm.

Philobryids and cyamiids are absent from the

72 The Nautilus

April 27. 1978

Vol. 92 (2)

Arctic and east Greenland faunas. Many of the

families which show the greatest diversity of

species in deep or shallow cold water (5° C or less)

never attain a large size, even where their

representatives are found in warmer water. The

deep-sea pelecypod fauna is dominated by pro-

tobranchs (Knudsen, 1970), which rarely attain a

size of more than 75 mm.

The largest species of a genus or a family may be

found in the coldest water. For example, Limopsis

rmrionensis Smith is the largest living species of

limopsid and occurs in the Antarctic region. The

largest species of Limatula lives in Arctic and

boreal waters.

It is interesting to compare the sizes and

distributions of two superficially similar marine

pelecypod families, the Limopsidae and the

Glycymerididae. The latter family is commonly

found in warm shallow water, but a few species live

in temperate or cool -temperate water. Glycymer-

idids are absent from the Antarctic, the Arctic, and

the deep sea. The maximum size of the largest liv-

ing glycymeridid is about 125 mm, and several

other species nearly attain that size. The largest

limopsid is about 80 mm and almost all species at-

tain only half that size or less. The limopsids are

found mainly in the Antarctic and in deep water

but are absent from the Arctic region. One method

of distinguishing many species of glycymeridids

fi-om limopsids is the larger size of the species of

the former family (Nicol, 1967a).

The calcareous-shelled marine gastropods have a

much less pronounced trend toward having more

large-sized species living in warm water (fig. 1).

Furthermore, a few species of cold-water gastro-

pods do attain a size of more than 100 mm in the

Antarctic and Arctic. One species of Antarctic

gastropod has been recorded attaining a size of at

least 107 mm, and four species of Arctic gastropods

attain a size of more than 100 mm, with a max-

imum size of 142 mm recorded. TTiese larger max-

imum sizes for cold-water gastropods are even

more surprising because the average size for

marine gastropod species is considerably less than

for marine pelecypod species. For every species of

marine pelecypod, there are probably three species

of marine gastropods, and the major increase in

gastropod diversity is among the small ones of 10

mm or less in size. Table 1 is a summary of the

number of species of gastropods and pelecypods in

14 marine faunas broken down into six size classes.

Table 1 clearly shows that the percentage of

gastropods declines as the shell sizes increase, and

the reverse is true for the pelecypods. Above 50 mm

there are actually more pelecypod than gastropod

species, even though gastropods comprise 70% of

the overall total of the six size groups. All size

classes of 20.1 mm and above have less than 70%

gastropod species. Among the very smallest species

(5.0 mm or less), the gastropods comprise 88% in

all 14 marine faunas.

There is a high percentage of small -sized species

of gastropods, as compared to small-sized species of

pelecypods, in both cold and warm water faunas. Of

the small species in the eastern Pacific faunas at

Puget Sound, southern California, and the warm-

water Panamic fauna, more than 85% are

gastropods. The other faunas having a higher than

average percentage of small-sized gastropod species

are the Arctic and the French Mediterranean

faunas. Both of the coldest water faunas, the Arctic

and Antarctic, have an uncommonly large per-

centage of gastropods of more than 50 mm as com-

pared to pelecypod species of that size. Among

species of more than 50 mm in size, the ratio of

TABLE 1. Marine gastropod and pelecypod species placed in

six size classes and (he number and percentage of gastropod

and pelecypod species in each size class.

Vol. 92 (2)

April 27, 1978

The Nautilus 73

gastropods to pelecypods is 74:26 in the Arctic and

73:27 in the Antarctic. In New Zealand and Vic-

toria, Australia, the ratio in this large size class is

55% gastropods and 45% pelecypods. In no other

regional fauna do large-sized gastropod species out-

number large-sized pelecypod species. From these

data we see some regional similarities in adjacent

faunas in these percentages— the uncommonly high

percentage of small-sized gastropod species in the

eastern Pacific faunas and the rather high per-

centage of large-sized gastropod species, as com-

pared to large-sized pelecypod species, in the New-

Zealand and Victoria, Australia, faunas.

There is a smaller number (not percentage) of

large gastropod species in cold water than in warm

water, as the numbers in fig. 1 attest: one in the

Antarctic, two in Iceland, 14 in New Zealand, 37 in

the tropical eastern Pacific, and 28 in the Carib-

bean. However, the percentage of species of

gastropods that attain a size of more than 100 mm

in warm- and cold-water marine faunas remains

nearly the same at all latitudes because of the

much greater number of small-sized gastropods in

the tropical faunas. Unfortunately, size data on

small-sized gastropods in almost all of the diverse

tropical gastropod faunas are definitely inade-

quate. The size ranges of warm-water gastropods

are much greater than in cold-water gastropods.

The largest living marine gastropod is Syrinx

anianus (Linne), which reaches a length of 610 mm

(Rippingale and McMichael, 1961). This maximum

size is still much less than that of Tridacna gigas.

Syrinx aruanns lives along the shores of Queens-

land and northern Australia.

Seventy per cent of all gastropod species in the

Antarctic attain a size of no more than 10 mm. The

New Zealand gastropod fauna also has a surpris-

ingly high percentage of small-sized species (52%).

These regional anomalies of a high percentage of

small-sized species of gastropods in cold and

temperate water of the Southern Hemisphere are

like those found in the marine pelecypods.

The size trend toward a higher percentage of

large-sized species in warm water is much more

pronounced in marine pelecypods than it is in

marine gastropods, perhaps because the pelecypods

are a much simpler and less diverse group, and

their size is affected by fewer biological factors.

Almost all marine pelecypods can be considered

either suspension or deposit feeders. The suspen-

sion feeders are by far the more common, and all of

the truly large pelecypods are suspension feeders.

The protobranchs are all deposit feeders, and the

largest living species attains a length of only 107

mm. Among the deposit-feeding tellinaceans (the

Semelidae and the Tellinidae), one species of

tellinid attains a size of about 116 mm. All other

species belonging to the semelids and tellinids are

small (Nicol, 1964). On the other hand, the much

more diverse gastropods have a wide variety of

feeding habits. Besides deposit and suspension

feeders, some gastropods are carnivores, others are

herbivores, and still others are parasites. These

three other modes of feeding would certainly have

some effect on the size the animal would need to

attain in order to be successful in its particular

niche or feeding habit. Thus, while the size of

marine pelecypods is affected chiefly by tempera-

ture, the size of marine gastropods is affected by

other factors as well, with the result that a greater

range of gastropod sizes is found in cold water.

By far the two most common groups of fresh-

water pelecypods are the naiades and the pisidiids.

The naiades are seldom less than 25 mm, are com-

monly more than 100 mm, and may attain a size of

280 mm. The pisidiids are small, but a few species

reach medium size (25 mm). The naiades attain

almost as large a size in temperate fresh-water as

they do in warm fresh-water. Naiades are not

found in the regions where the water is coldest. For

example, only pisidiids occur in Patagonia or south

of the Rio Negro in Argentina. As one goes north-

ward from the Rio Negro to the La Plata River, the

number of species of naiades increases (Pilsbry,

1911, pp. 513-514). The only fresh-water pelecypods

in Iceland are four species of pisidiids (Mandahl-

EJarth, 1938). As further proof of the distribution of

these two groups of pelecypods, one has only to look

at the distribution maps of the fresh-water

pelecypods of the Canadian interior basin (Clarke,

1973). Almost no species of naiades are found as far

north as 60° north latitude, but many species of

pisidiids occur north of that latitude, and some

range as far north as 70° north latitude. There is a

clear trend of a higher percentage of large-sized

74 The Nautilus

April

1978

92 (2)

FRESH-WATER

LAND

PELECYPOOS

•Ok

I

s

< 301 301- )'000

GASTROPODS

(10 1 101- >30 0

SIZE MM

< 10.1 101 -

FIG. 2 Frequency histograms showing percentages of species

in three size classes in freshwater pelecj/pod and gastropod

faunas and land gastropod faunas.

one can see that there is little change from the

smallest size class up to 30 mm. Above this size, the

percentage of pelecypods increases rapidly, and

above 50 mm the pelecypods comprise 81% of the

molluscan species in all of the faunas. The rather

steady increase in pelecypod percentages in all size

classes in the marine faunas is not seen in the

freshwater pelecypods. In the coldest freshwater

molluscan faunas analyzed, there is a low percen-

tage of small-sized species (10 mm or less) of

gastropods as compared to small-sized pelcypod

species. Wisconsin has only 53% small-sized

gastropod species, Scandinavia 65%, and

Czechoslovakia 69%. All other regions analyzed

had 76% or more small-sized species of freshwater

gastropods. No other size trends were seen in the

ratios of gastropods to pelecypods in freshwater.

The largest freshwater gastropods are found in

the tropics, and, unlike the marine gastropods, the

freshwater repjresentatives show a clear trend

toward larger size in warm water. One regional

anomaly is the high percentage of small freshwater

gastropods in the New Zealand fauna, as seen in

Fig. 2.

freshwater pelecypods living in warm water as

shown in Fig. 2.

There is at least one r^ional anomaly. It is the

uncommonly high percentage of naiades, which at-

tain a large size, found in Wisconsin as compared

to Scandinavia. The central and eastern United

States is noted for its diverse naiad fauna.

A major problem in getting adequate faunal data

is that some large islands have surprisingly few

species of freshwater pelecypods: New Caledonia

has only one species, New Zealand has only eight,

and Java has sixteen.

Freshwater gastropods are generally smaller

than freshwater pelecypods. The maximum size of

any freshwater gastropod is about 200 mm. The

following table (Table 2) is a summary of 12 fresh-

water molluscan faunas comparing the percentage

of gastropods and pelecypods in six size classes.

Although the ratio of total numbers of gastropod

species to pelecypod species is approximately the

same in freshwater as it is in the seas, the ratio in

some size classes is quite different. From Table 2

TABLE 2. Freshwater gastropod and pelecypod species

placed in sij- size classes and the number and percentage of

gastnypod and pelecypod species in each class.

Vol. 92 (2)

April 27. 1978

The Nautilus 75

Calcareous-shelled land gastropods tend toward

large size in the tropics, but the trend is not as pro-

nounced as in the freshwater gastropods and

pelecypods. The giants among land snails are the

Achatinidae, and they are endemic to Africa south

of the Sahara. Maximum size of a species of

achatinid is about 200 mm. The Achatinidae thrive

in warm and moist regions, and such areas as the

Belgian Congo have a high percentage of large-sized

species of land gastropods because this family has

many species living there. Small- to medium-sized

land gastropods predominate in arid regions, such

as Algeria and Western Australia, and, surprising-

ly, they also predominate in New Zealand, which is

not arid. Perhaps the large number of small- to

medium -sized land gastropods in the fauna of New

Zealand can be accounted for by aerial dispersal by

wind and birds. Vagvolgyi (1976) points out that on

Pacific islands the land snails are commonly less

than 10 mm in size and that the dispersal of these

gastropods is by aerial means to these remote

islands. This may also be a factor in the distribu-

tion of small-sized freshwater gastropods and

pelecypods.

In each of the 13 faunas studied, the land

gastropods have about the same size range and

maximum size as the freshwater gastropods in the

same region. The average ratio of land snails to

freshwater snails is 79:21 in the three smaller size

groups (30 mm or less) and 67:33 in the larger size

groups.

The range in size within a group of animals is

considered by ecologists to be a factor in diversity

because two species that differ considerably in size

are not in direct competition with one another. The

ratio of the largest species to the smallest species,

or absolute size ranges, is shown in Table 3 for the

marine pelecypods and gastropods, the freshwater

pelecypods and gastropods, and the land gastro-

pods. The marine pelecypods have a somewhat

greater size range than the marine gastropods but

"are actually a much less diverse group. The main

cause for the greater size range in the marine

pelecypods is the exceedingly large size of one

species, Tridacna gigas, which is more than twice as

large as any other living marine pelecypod.

Although the size of the largest species of fresh-

water pelecypod is greater than the largest species

of freshwater gastropod or land gastropod, the ratio

TABLE 3. The size range of each of the groups of living

xpecies studied and the ratio of these ranges.

of largest to smallest species of freshwater

pelecypod is less than it is in the freshwater

gastropods and land gastropods. This may be one of

the reasons why the freshwater and land gastro-

pods are more diverse than the freshwater

pelecypods.

SPECIES DIVERSITY

As a by-product of the study on size trends, some

data on diversity were gleaned from an enumera-

tion of all of the species in each fauna. In Table 1 it

can be seen that gastropods comprise 70% of all

calcareous-shelled species of gastropods and

pelecypods in the 14 marine faunas. This would be

a ratio of seven gastropod species to three

pelecypod species. No regional trends could be

discerned within the 14 marine faunas, but it is

obvious from the data that most of the small species

of warm-water gastropods were inadequately

covered.

The total in Table 2 of all species of freshwater

gastropods and pelecypods shows that freshwater

gastropod species outnumber freshwater pelecypod

species approximately seven to three, the same as

in the marine faunas. Of the 12 freshwater

molluscan faunas analyzed, only the Wisconsin

fauna had a greater number of pelecypods than

gastropods because of the large number of naiad

species in this fauna. The areas of low annual rain-

fall seem to have a lower average percentage of

pelecypods, as for example, Algeria with only 21%

pelec\TX)d species. Besides many large islands, some

of the continental regions have a surprisingly low

number of freshwater pelecypod species— Algeria

17, South Africa 16.

In the 13 land and freshwater gastropod faunas

analyzed, there is a ratio of 39 land-gastropod

species to 11 freshwater gastropod species. This, of

course, excludes the land slugs, which would make

76 The Nautilus

April 27. 1978

Vol. 92 (2)

this ratio slightly higher in favor of the land

gastropods. New Zealand has an impoverished

freshwater molluscan fauna. The freshwater

species of pelecypods were mentioned earlier, but

there are also only 27 living species of freshwater

gastropods, which comprise only 8% of the non-

marine gastropod species of New Zealand. In the

non-marine gastropods of British India, 84% are

land species and only 16% are freshwater species.

These are the two most exceptional deviations from

the normal percentages of land and freshwater

gastropod species in the 13 faunas analyzed.

After comparing the number of species of

marine, freshwater, and land gastropods and

marine and freshwater pelecypods in more than '^)

well documented faunas, I now believe that my

estimate of 107. IW) living species of mollusks is too

high (Nicol,1969). The estimate given by Boss (1971)

of 46,810 living species is probably nearer the truth.

My main reason for believing this is based on the

surprisingly small number of freshwater

pelecypods on some large islands and even on some

large continental areas. To a lesser extent, this is

also true of the freshwater gastropods. Several

years ago Dr. J. P. E. Morrison told me of his

estimate that there are no more than 2,000 living

species of freshwater pelecypods. I am inclined to

believe that even this figure is too high and that

perhaps 1,500 living species of freshwater

pelecypods is a more accurate estimate. Taking

1,500 living species as a base, there would then be

about 3,500 living species of freshwater gastropods,

using the seven to three ratio shown in Table 2. In

this way one could estimate the number of living

land gastropods from the freshwater gastrop<id

estimate. Also, one could estimate the number of

marine gastropods from an accurate count of the

marine pelecypod species.

CONCLUSIONS

It has been noted that broken sea urchin spines

are regenerated or calcified more rapidly when

these animals are placed in warm water (Davies et

al.. 1972). Calcium carbonate is more readily ob-

tainable in warm water by animals needing it for

skeletal material, and the metabolism of these

animals increases at higher temperatures, thus

utilizing calcium carbonate more rapidly. TYiis at

least partially explains the trend toward larger

size at warm temperature in most animal groups

that use calcium carbonate.

Besides the physical factors affecting size trends

in the groups analyzed herein, there are biological

factors that alter a particular trend locally and

bring about regional anomalies. One of these

biological factors is genetics. It seems obvious that

the naiades have genes for large size whereas the

pisidiids have genes for small size. Geographic

distribution and regional diversity are also impor-

tant factors. As an example: the central and

eastern United States has an uncommonly high

diversity of naiades, giving these faunas in

temperate freshwater an unusually high percen-

tage of large-sized species of pelecypods. In nor-

thwestern Europe the naiad fauna is not nearly so

diverse even though the freshwater in this region is

no colder than it is in parts of the United States.

Ecological factors are also important. Many

suspension feeders attain a large size, whereas

parasites and many commensals are small.

Amongst the p3elec>TX)ds, there are relatively few

species of commensals and apparently no parasites.

The erycinacean pelecypods are generally com-

mensals and are among the smallest -sized marine

species. The marine gastropods, on the other hand,

have a large number of parasitic species and com-

mensal species. TTiis is undoubtedly an important

reason why there are so many more small-sized

marine gastropods than pelecypods. These

biological factors that we see occurring today were

likewise operating throughout at least the

Phanerozoic to a considerable degree. This explains

why we see some fossil marine faunas that have an

uncommonly high percentage of small-sized or

large-sized species.

Besides sorting by wave and current action and

other physical factors, we must bear in mind the

biological factors as well. Therefore, we must know

something of the life habits, the size range of the

genus or family, and the geographic distribution of

each group represented in the fossil fauna, because

in certain regions biological factors may be more

important than physical factors in determining the

sizes of species in a particular fauna.

Vol. 92 (2)

April 27. 1978

The Nautilus 77

RELIABILITY OF THE DATA

In analyzing a fauna, it is most important to

know the group well in order to evaluate the

reliability of the data taken from each faunal

monograph and also to avoid the pitfall of in-

complete coverage of the group in a specific region.

All too commonly the title of a paper fails to in-

dicate that the coverage is not complete. For exam-

ple: I found a monograph on freshwater

pelecypods of Australia that seemed to suit my

purposes perfectly; but after recording the size of

all the species, I found that the monograph covered

only the naiades, all of which are of medium to

large size. If I had relied on this paper, 1 would have

come to the erroneous conclusion that there are no

small-sized species of fresh-water pelecypods in

Australia. I found that older faunal monographs

should generally be avoided, if there is a more re-

cent treatment of the same group in the same

region. The older faunal monographs frequently

have two drawbacks: (1) the coverage of the group

is not exhaustive, particularly the small-sized

species: (2) the large-sized species, at least of the

naiades, are commonly split too much.

Some monographers do not adequately cover the

small-sized species. However, I feel that the marine

pelecypod data are reliable because most marine

pelecypods are not small. I also feel confident that

the freshwater pelecypod data are reasonably ac

curate. The marine gastropod data are less accu-

rate. Small-sized gastropods in warm-water marine

faunas are poorly covered and frequently the

descriptions include no accurate information on

size. In some of these instances, the size group of

the species can only be estimated. I am less certain

of the absolute accuracy of the size data of the

freshwater and land gastropods because of my lack

of knowledge of these groups.

In some instances I had to take size data that

were not in the metric system and convert them.

Fractions of inches are not so accurate as

measurements in millimeters, and there is also the

possibility of error in the process of conversion

from inches to millimeters.

Some of the references that were first analyzed

were later discarded as untrustworthy or

repetitious. Only those publications used in the

final analysis of the data are listed in the

references at the end of this paper.

It is imperative that a taxonomist do this kind of

analysis because the taxonomist has the kind of ex-

perience and knowledge that is necessary to

evaluate the reliability and completeness of the

basic data.

ACKNOWLEDGMENTS

I am indebted to many people who gave me ad-

vice and suggestions on size data. Dr. Joseph

Rosewater and Mr. Walter J. Byas of the Division

of Mollusks at the National Museum of Natural

History were particularly helpful on size data of

the land and freshwater gastropods. Dr. Joseph P.

E. Morrison, also of the Division of Mollusks at the

National Museum of Natural History, showed me

the largest freshwater gastropods. Dr. Leo

Polopolus, chairman of the Department of Food

and Resource Economics at the University of

Florida, gave me some excellent suggestions on

statistical treatment of the size data.

LITERATURE CITED

Baker, F. C. 1928a. The Fresh Water Molhisca of Wisconsin.

Part I. Gastropoda. Wisconsin Geol. Nat. Hist. Surv. Bull. 70.

507 pp.

Baker, F. C. 1928b. The Fresh Water Molhisca of Wisconsin.

Part n. Pelecypoda. Wisconsin Geol. Nat. Hist. Surv. Bull. 70.

495 pp.

Baker, F. C. 1939. Fieldbook ofBlinois Land 5«mk. Illinois Nat.

Hist. Manual 2. 166pp.

Barnard. K. H. 1963. Contributions to the knowledge of South

.African marine Mollusca. Parts I & II. Ann. South African

Mus. 47: 1-360.

Barnard, K. H. 1964. Contributions to the knowledge of South

African marine Mollusca. Part V. Lamellibranchiata. Ann.

South African Mus. 47: 361-593.

Be'. A. W. H. 1968. Shell porosity of Recent planktonic

Foraminifera as a climatic index. Science 161: 881-884.

Blanford, W. T., and Godwin-Austen. 1908. The Fauna of British

India. Including Ceylon and Burma. Mollusca Vol. I,

Testacellidae and Zonitidae. Taylor & Francis, London. 311

pp.

Boss, K. J. 1971. Critical estimate of the number of Recent

Mollusca. Occasional Papers on Mollvsks, Harvard Univ. 3:

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STATUS OF EULIMA SUBCARINATA ORBIGNY, 1842

ANDE'. CAROLII BALL, 1889 (GASTROPODA: MELANELLIDAE)'

William G. Lyons

Florida Department of Natural Resources

Marine Research Laboratory

St. Petersburg, Florida 33701

ABSTRACT

Eulima subcarinata Orbigny. 18^2. is redescribed and transferred to the genus

Eulimostraca Bartsch, 1917. The species occurs from the Caribbean and Yucatan to

intermediate-depth shelf waters off Florida and North Carolina. Confimon regard-

ing the species' identity is discussed. Eulima carolii Dall. 1889 (formerly affinis C

B. Adams. 1850. non Philippi. 18U) is considered a nomen dubium.

Orbigny (1842) introduced the name Eidima

subcarinata for a small melanellid from

Guadeloupe, West Indies. Among the characters

included in his Latin description (1845) were "an-

frartibus octonis. . . linea fulva omatis. ultimo

subcarinato". expanded in French (1853) as 'ie

dernier [tour] un peu carene en avant. . .

Couleur. Blanc uniforme avec une legere bande

jaunatre ou fauve sur la partie carenee an-

terieure." His illustrations (1842, pi. XVL Figs.

4-6) were somewhat schematic, depicting a shell

' Contribution no. 316, Florida Department of Natural

Resources, Marine Research Laboratory.

of typical, unomamented melanellid form but

with a peripheral line suggesting a low carina on

the last whorl.

Morch (1875) reported the species from St.

Thomas [Virgin Islands]; and Dall (1889a) ex-

tended the range to the southeastern United

States. No subsequent records have appeared,

although the name has been continuously used in

compilation lists of western Atlantic marine

mollusks.

I recently examined the holotype of Eulima

subcarinata, presently in the British Museum of

Natural .History |BM(NH)1. The shell (Fig. la).

80 The Nautilus

April 27, 1978

Vol. 92 (2)

FIG. 1. Euliniostraca subcarinata (Orbigny. 1812): a.

holot!/i>('. J.l mm, Guadeloupe: b. adult shell, 34 mm, off Ef;-

mont Key. Florida, FSBC I lOflHt! (both XJO).

although faded, badly worn, and possessing a

large hole drilled by another gastropod on the

back side of the penultimate whorl, agrees in all

other respects with Orbigny's description. It is

conspecific with others from U. S. Fish Commis-

sion (USFC) collections in the National Museum

of Natural History (USNM), Washington, D.C.,

and additional shells in the Delaware Museum of

Natural History (DMNH), Greenville, Delaware,

and the Florida Department of Natural Re-

sources Marine Research Laboratory (FSBC I), St.

Petersburg, Florida. These specimens have

allowed a more complete description of the

species and better understanding of its

phylogenetic position and its geographic and

bathymetric range. In addition, some of the

specimens create doubt regarding the accuracy of

Dall's (1889a) treatment of several melanellids

from the southeastern United States.

Eulimostraca subcarinata (Orbigny, 1842)

new combination

(FiKS. la. b)

Description: Shell small, length to about 3.6

mm, straight, glossy, with evenly tapering, slight-

ly convex whorls. Protoconch extremely sharp.

slender, of about 3*2 whorls, merging almost im-

perceptibly with spire. Teleoconch with about 6''2

smooth, slightly convex whorls; central portion of

each whorl light golden brown, with a thin,

brown spiral line at each suture; periphery of

body whorl rounded, with a distinct brown spiral

line. Aperture about Vt shell length, broadly

ovate, rounded but not extended anteriorly,

slightly attenuated behind; posterior half of outer

lip brown, color diminishing anteriorly at ter-

mination of peripheral line; inner lip dark

brown, curved, thickened, forming a shallow, nar-

row umbilical depression.

Material examined: HOLOTYPE: BM(NH)

Reg. no. 18M. 10.4.141, cat. no. 129; 1 dead, length

3.1 mm, Guadeloupe. NORTH CAROLINA: 1

dead, USFC sta. 2597, south southwest of Cape

Hatteras, 27 m (USNM 97516); 2 dead, USFC sta.

2598, south southwest of Cape Hatteras, 40 m

(USNM 94570); 1 dead, 3.2 mm, USFC sta. 2608,

off Cape Lookout, 40 m (USNM 83274); 1 dead,

USFC sta. 2608 (same) (USNM 94803); 5 dead +

1 fragment, 2.0-2.5 mm, USFC sta. 2608 (same)

(USNM 97530); 1 dead, 3.3 mm, USFC sta. 2610,

southeast of Cape Lookout, 40 m (USNM 92810);

1 dead, USFC sta. 2610 (same) (USNM 97515); 3

dead, USFC sta. 2611, southeast of Cape Lookout,

57 m (USNM 92809). FLORIDA: 1 dead, RSP sta.

003, 28° 37' N, 80° 11.2' W, off Cape Canaveral, 40

m, January 16, 1973 (FSBC I 11177); 2 dead, RSP

sta. 003 (same), November 2, 1973 (FSBC I 11178);

6 dead, RSP sta. 003 (same), November 5, 1974

(FSBC I 11179); 1 dead, south of Dry Tortugas,

192 m (DMNH 114557); 4 dead, 2.6-3.1 mm, west

of Naples, 55 m (FSBC I 15030); 1 dead.

Hourglass sta. K, 26° 24' N, 82° 58' W, off Sanibel

Island, 37 m, November 14, 1967 (FSBC I 10885);

1 dead + 5 fragments, Hourglass sta. L, 26° 24'

N, 83° 22' W, off Sanibel Island, 55 m, September

5, 1966 (FSBC I 10884); 1 dead, 60 mi (97 km)

west southwest of Johns Pass, 68 m (DMNH

114556); 4 dead, south southwest of Johns Pass,

62 m (DMNH 114.553); 1 dead, 3.6 mm. west

southwest of Johns Pass, 46 m (DMNH 114552);

2 dead, 3.3-3.4 mm. Hourglass sta. B, 27° 37' N,

83° 07' W. 18 m. November 2, 1967 (FSBC I

10886); 2 dead, Clearwater Beach (DMNH

114555). MEXICO: 1 dead, northeast of Contoy

Light, Yucatan, 119m (DMNH 1145.54).

Vol. 92 (2)

April 27, 1978

T>ie Nautilus 81

Range: Off North Carolina, both coasts of

Florida, and Yucatan, 18-192 m; St. Thomas (?)

and Guadeloupe, West Indies.

Remarks: Orbigny's species belongs to the

genus Eulimostraca Bartsch, 1917, a group of

small melanellids with slender, acute apices, flat-

tened to slightly rounded whorls, broadly ovate

apertures, and brown markings on the shell.

Keen (1971) listed two eastern Pacific species, in-

cluding E galapagensis Bartsch, 1917, the type

species of Eulimostraca. This species is quite

similar to E mbcarinata, but apparently has

more slender anterior whorls and lacks brown

marking on the columella or inner lip. Eu-

limostraca bartschi Strong and Hertlein, 1937,

from Mazatlan, west Mexico, lacks a brown spiral

line and is considerably smaller, having nine

whorls in a total length of only 1.8 mm. No

western Atlantic species have been previously

assigned to Eulimostraca, but several evidently

belong here, including Eidima hemphillii Dall,

1884 (subsequently placed in Leiostraca,

Melanella, and Strombiformis by various

authors), and several other species, presently

undescribed, which occur in the Bahamas and off

both Florida coasts.

Shell color and peripheral markings of E. sub-

carimta (Fig. lb) are strikingly like those of Niso

aeglees Bush, 1885. The two species occur together

throughout at least the continental range of E.

subcarinata, but can hardly be confused. The

shell of Niso aeglees is larger, broader, and

strongly umbilicate.

The holotype of Eulima subcarinata is a nearly

mature shell still bearing suggestions of the

angled periphery common on juveniles of many

melanellid species. This feature is probably the

source of Orbigny's description of peripheral

carination, for fully mature adults lack such

angulation. Tryon (1886) reported the last whorl

to be "obtusely carinated", but his illustration (pi.

69, Fig. 44) depicted a shell with both a peripheral

carina and numerous well defined axial striae

nearly the size of riblets, the latter character

unknown on any western Atlantic melanellid. It

is quite dissimilar from Orbigny's illustration

and from the holotype.

Dall (1889a) briefly reviewed the West Indian

Eulimidae ( = Melanellidae). He did not mention

Tryon 's figure of E. subcarinata, but assigned

another on the same plate (pi. 69, Fig. 36) to that

species. Tryon had assigned that figure to E.

oleacea Kurtz and Stimpson, 1851, but Dall stated

it was not appropriate for that species. The figure

is too small and imprecise to be assigned with

certainty to either species. Dall also extended the

range of E. subcarinata from the Antilles to

Florida and [Cape] Hatteras, but his concept of

this "carinate" species may have been influenced

incorrectly by Orbigny's description and Tryon 's

later error. All USNM specimens designated E

subcarinata by Dall have proved, upon inspection,

to be worn shells of various other melanellids,

usually with the lip broken back to produce a

"carina" on the penultimate whorl.

C. B. Adams (1845) described EMima jamaicen-

sis, and soon thereafter (1850) described five addi-

tional melanellid species (E. affinis, E arcuata,

E conica. E fulvocincta. and E gracilis) from

Jamaica. Dall (1889a) recognized arcuata, gracilis.

and jamaicensis as valid species, synonymized

fulvocincta, and proposed a new name for affinis,

pointing out that Adams' name was preoccupied by

Eidima affinis Philippi, 1844. He renamed Adams'

species Eulima carolii. Dall suggested that he had

examined the types of arcuata and jamaicensis. and

evidently had access to Adams' specimens of conica

and fulvocincta as well (Lyons, 1977), but there

is no evidence to indicate he had seen Adams' type

of affinis.

Dall's concept of Adams' affinis was apparently

incorrect. He (1889a) applied most Adams' names

to other specimens of western Atlantic Me-

lanellidae, identifying eight lots as E carolii and

redefining its range to include "Florida to North

Carolina, in 8-63 fins" (15-105 m). Dall's carolii

material actually contains several species, with

most specimens in very poor condition. Five of

the lots, all USFC collections from off North

Carolina, contain Eulimostraca subcarinata.

However, neither his 15-meter nor his 105-meter

lot, from which he established the bathymetric

range of carolii, contain subcarinata. The type of

affinvi Adams is missing (Clench and "Turner,

1950), but its description fits none of Dall's

material especially well. Adams' description of

affinis was brief, being a comparison of several

characters separating it from Eulima conica

82 The Nautilus

April 27. 1978

Vol. 92 (2)

which he described on the same page. He noted £

conica to be white; by inference, this must apply

to affinis as well, demonstrating that the brown-

marked f»ibcarinata specimens are not carolii.

Apparently, none of Dall's material is actually

carolii. and his records should be rejected. Until

Adams' type is located, the name should be con-

sidered a nomen dubium. To my knowledge, no

subsequent specimens of E. carolii have been

reported, although the name has appeared on

several faunal lists (Dall, 1889b; Johnson, 1934;

Abbott, 1974) repeating Dall's information.

Identity of specimens Dall (1889a: p. 329) men-

tioned "with brown varices and a brown

peripheral line, which I have only fragments in-

sufficient fully to characterize" is uncertain. He

was probably referring to three additional

unidentified lots of USFX^ material also contain-

ing E. subcarinata^ but none of these shells have

brown varices (areas of arrested shell growth

where color markings sometimes occur on

melanellids). Eidimostraca subcarinata lacks such

markings. It is possible that Dall's remark

referred to the brown marking on the posterior

portion of the outer lip of E. subcarinata. but

there is only one such marking per shell on that

species, whereas Dall implied more than one

brown varix. At least one of the undescribed

south Florida Eulimostraca has browm varices,

but it lacks a peripheral line. Moreover, I found

no specimens of that species in collections

available to Dall.

Morch's (1875) record of E. subcarinata from

St. Thomas must remain in question until the

specimens are examined. It could have been

Eulima auridncta Abbott, 1958, a shell of similar

size, with a slightly angled periphery on the

penultimate whorl and bearing a brown or golden

band on each whorl. The latter is common in beach

drift throughout the northern Caribbean.

Beached specimens of Eulimostraca sub-

carinata are rare; I have seen only the lot from

Clearwater Beach, Florida (DMNH 114555),

although Orbigny's type and Morch's record, if

correct, may have been similarly obtained. In the

southeastern United States, the species is evident-

ly most common along the intermediate portion

of the continental shelf in depths of about 18 to

62 m. Such occurrence often indicates northern

submergence of shallow-water Caribbean species,

but I have not seen E. subcarinata among many

melanellids from shallow collections in the

Florida Keys and Bahamas. I have examined only

single juveniles (1.6, 1.8 mm), from off Dry Tor-

tugas and Yucatan respectively, taken from depths

greater than 62 m, suggesting that adult popula-

tions may not occur at greater depths.

ACKNOWLEDGMENTS

Ms. Kathie Way, British Museum (Natural

History), London, kindly loaned the holotype of

Orbigny's species. Dr. Joseph Rosewater, Curator

of Mollusks, National Museum of Natural His-

tory, Washington, D.C., provided access to those

collections and later loaned material; he and

fellow staff members provided many courtesies

during my visit there. Mrs. Barbara Steger. Tam-

pa, Florida, and later Dr. R. Tucker Abbott, both

provided material from the Steger collection, now

at the Delaware Museum of Natural History.

Mi-s. Sally D. Kaicher, St. Petersburg, photo-

graphed the figured specimens. Dr. Anders

Waren, University of Goteborg, Sweden, is

thanked for discussions regarding identities of

Florida and Caribbean Melanellidae. Dr. Donna

D. Turgeon and Mr. David K. Camp kindly read

the manuscript. All are gratefully acknowledged.

LITERATURE CITED

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18.50. Descriptions of supposed new species of

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Vol. 92 (2)

April

1978

The Nautilus 83

1889b. A preliminary catalogue of the shell-

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melanellid species. Occ. Papers on Mollusks (Harvard) 4(5.5):

149-1.57.

Morch, 0. A. 1875. Synopsis Molluscorum marinoruni India-

rum occidentalium.A/o/. Rlat. 22: 142-18-1.

Orbigny, Alcide. 18-12. Histoire physique, politique et

naturelle de I'lle de Cuba par M. Ramon de La Sagre. Atlas,

28 pis.

1845. Historia ffsica, polttica y natural de la Isla

de Cuba p(jr D. Ramon de La Sagre. Part 2 Historia

Natural, vol. 5, Moluscos: .'376 p.

18.5.3. Histoire physique, politique et naturelle de

rile de Cuba par M. Ramon de La Sagre. Tome 1: 264 p.;

Tome 2: :«0 p., 42 pis.

Tryon, G. W., Jr. 1886. Eulimidae. Manual of ConchoUyii. ser.

1,8: 258-293, pis. 68-71.

HEBETANCYLUS EXCENTRICUS (MORELET) (PULMONATA:

ANCYLIDAE) IN LOUISIANA AND A REPORT OF SEPTUM FORMATION

Hugh M. Turner'

Department of Zoology and Physiology,

Louisiana State University,

Baton Rouge, Louisiana 70803

ABSTRACT

Hebetancylus excentricus is first reported from Louisiana where it is widely

distributed in shallow ponds and streams in the southeastern part of the state. An

18-month survey of one population revealed polymorphism irith certain individuals

forming a septum, which partially closed the shell aperture. Septum formation, not

previously reported for the species, was of seasonal occurrence.

The freshwater limpet Hebetancylus excen-

tricus has a Caribbean distribution, but has been

reported in North America from southern Flor-

ida and coastal Georgia (Basch, 1963), south-

central Texas (Pilsbry, 1889; Walker, 1903), north

central Texas (McMahon and Aldridge, 1976), and

southern Oklahoma (McMahon et ai. 1976).

H. excentricus is here reported to be widely

distributed on emergent vegetation in shallow

streams and ponds in southeastern Louisiana,

where it often occurs sympatrically with the

other ancylids, Laevapex fuscus and Ferrissia

fnujilia. H. excentricus probably has an inter-

rupted Gulf Coast distribution occurring in en-

claves where suitable ecological conditions exist.

' Present Address: Department of Biology, NcNeese State

University, Lake Charles, Louisiana 7(160*1

Louisiana habitats differ from those reported

for other North American populations. Basch

(1963) reported their occurrence on floating and

deep .submerged debris in canals and ditches,

while McMahon and Aldridge (1976) collected

them on the surfaces of rocks in fast flowing

streams.

Richardot et al (1972) reported that under cer-

tain undetermined environmental conditions, and

among certain individuals in populations of the

European ancylid, Fenissia wautieri, peripheral

shell growth ceased and a septum or thin

horizontal calcareous shelf was formed. This sep-

tum, which was deposited by the posterior

margin of the mantle and was of the same com-

position and crystalline structure as the shell,

partially" closed the aperture. Later, when

84 The Nautilus

April 27, 1978

Vol. 92 (2)

30

25

O 20

3

a

o

Q.

SEPTATE PHASE

POST- SEPTATE PHASE

il

1

I I I

JJASONDJFMAMJJASON

MONTH

Fid. 1. Percent Hebetancylus excentricus population in

either xeptaie or post-septate phases.

peripheral shell deposition resumed, growth was

from the margin of the constricted aperture and

resulted in what Parodiz (1957) called the "post-

septate" stage.

North American septate ancylids were assigned

to the genus Gundlachia; however, Basch (1963)

concluded that they were referable to the genus

Fi'trL'^sia. He also noted that habitats for septate

F. fragilis were temporary roadside ditches and

woods pools, both of which dried up during part

of the year. Septum formation has not been

reported for H. excentricvs.

Fid. 2. Septate Hebetancylus excentricus exhibitintj rnriims

degrees of septum fimiiat ion . Scale in mm.

FIG. :i Post-septate Hebetancylus excentricus. Sca/c in mm.

From June 1975 through November 1976, a

survey of an H. exeentticiis population was con-

ducted at a small stream on the Louisiana State

University Sheep Farm, East Baton Rouge

Parish, southeastern Loiusiana (30° 22' 11" N, 91°

ir 39" W). Collections were made twice monthly,

once during the first week and again during the

third week of each month. Data from both collec-

tions were pooled. A total of 3,700 H. excentricus

were removed from leaves and stems of alligator

weed, Alternathera sp., and taken to the

laboratory for study.

In October 1975 septate H. excentricvs, which

were anatomically identical in "soft-parts" to the

non-septate forms, appeared in the population. By

December and January they comprised 23% of

the population (Fig. 1). In February there oc-

curred a decline in septate forms accompanied by

a transition from septate to post-septate phase

(Figs. 2 and 3). This phase persisted in the

population until July and was replaced by non-

septate forms. During November 1976, the last

month of the study, septate forms reappeared

with 5% of the population involved.

The septum may serve as a fimctional

epiphragm permitting limpets to aestivate and

survive desiccation (Boss, 1974). However, it

should be noted that at no time during the study

did the water level in the stream approach

drought conditions, thus suggesting another

unknown reason for septum development.

Voucher specimens of septate H. excentricus

have been deposited in the Delaware Musuem of

Natural History (DMNH 108368).

ACKNOWLEDGMENTS

The author wishes to thank Dr. Robert F.

McMahon of the University of Texas at Arlington

for his help in preparation of the manuscript and

for confirming identification of the limpets.

LITERATURE CITED

Basch. P. F. 196.S. A review of the recent freshwater limpet

snails of North America (Mollu.sca; Pulmonata). Pull. Mux.

Owip. Zool. (Harvard) 129(X): 899-lHl.

Boss. K. .1. 1971. Oblomovism in Moilusca. Trans. Amer. Micro.

Soc. 93(4): 460-481.

Vol. 92 (2)

April 27, 1978

The Nautilus 85

McMahon. R. F. and D. W. Aldridge. 1976. New di.strihution

records for three spet'ies of freshwater limpet (Pulmonata:

Ancylidae) from north central Texas. Malac. Review 9:

124-12.5.

McMahon, R. F.. D. W. Aldridge, and G. L. King. 1976. New

distribution records for two species of freshwater limpet

(Pulmonata: Basommatophora) in southern Oklahoma.

Sovthmstem Nat. 21(2): 241-242.

Parodiz, J. J. 19,57. New records of freshwater gastropods from

the Bahama Islands. 4 /(«. Carnegie Miis. 35: 1-9.

Pilsbry, H. A. 1889. Recent additions to the United States

snail fauna. ITie Nautilus 3: 62-frl.

Richardot, M. G., G. Chassagne, and J. Wautier. 1972. Septum

fonnatiiiti in the freshwater limpet Ferrisaia wautieri

(Basommatophora: Ancylidae) under laboratory conditions.

Mdae. Reme^v5{2): 165-167.

Walker, B. 1903. Notes on eastern American ancyli. The

A'ajrfite 17: 13-19, 2.5-30,

FUSINUSSTEGERI {GASTROVODA: FASCIOLARIDAE), A NEW SPECIES

FROM THE EASTERN GULF OF MEXICO'

William G. Lyons

Florida Department of Natural Resources

Marine Research Laboratory

St. Petersburg, Florida 33701

ABSTRACT

Fusinus stegeri n. sp. from 100-205 frns (183-375 m) depths off western Florida

differs from F. eucosmius (Dcdl 1889) by its greater length (to 102 mm), white col-

or, and diminishing strength of axial ribs on anterior whorls. Fusinus eucosmius is

knoum only to depths of 89 fms (162 m). Twenty-six other names applied to

ivestem Atlantic Fusinus are listed.

(Commercial shell dredging during the past sev-

eral years has resulted in increased availability

of many deep water west Florida mollusks. A

species of Fusinus common among private shell

collections is here described. Specimens of the

new species are deposited in collections of the

Academy of Natural Sciences of Philadelphia

(ANSP), Pennsylvania, the American Museum of

Natural History (AMNH), New York, New York,

the British Museum (Natural History) (BMNH),

London, the Museum of Comparative Zoology

(MCZ), Cambridge, Massachusetts, the National

Museum of Natural History, Smithsonian Institu-

tion (USNM), Washington, D.C., and the Florida

Department of Natural Resources Marine Re-

search Laboratory (FSBC I), St. Petersburg.

Fusinus stegeri, new species

(Figures 1-5)

Description: Shell large, to at least 102 mm

' Contribution no. 317. Florida Department of Natural

Resources, Marine Research Laboratory.

total length, slender, fusiform, with about 13

whorls. Embryonic whorls about 2'/2, small,

elongate, flattened apically, with only slightly

convex lateral margins; last half whorl with

strong axial riblets. Nearly 11 postembryonic

whorls bearing prominent, swollen axial ribs, in-

creasing numerically but decreasing in strength

anteriorly; first five spiral whorls with 6 or 7

ribs, sixth whorl nearly always with 7 ribs, sev-

enth with 8-10, eighth with 9-13, ninth with

10-14, and tenth with 13-16 ribs. Spiral whorls

rounded, with strongly convex sides and con-

stricted sutures; each whorl crossed by 6-8, usual-

ly 7, prominent spiral cords. About 10 or 11

strong cords on body whorl, 9-12 on base,

sometimes with weaker cords between. Aperture

ovate, slightly constricted anteriorly and

posteriorly; parietal callous extended, forming

sharp, thin lamina (inner lip) along columellar

border of aperture ; lamina sometimes present but

reduced along columellar zone of anterior

86 The Nautilus

April

1978

Vol. 92 (-2

FIGS. 1-9. Western AtUuitiri' ?\isinus: 1. F. stegeri. n. nj).. hulotijite. 102 mm. I S.Wf TJ,»0S2: 2. mme. lateral tneie: 3. F. st^eri.

paratype, 97 mm. BMNH 197S10: 4. F. stegeri. parati/pe, 70.i mm. ANSP Slf5J,72: 5. same, tntenil riew: 6. F. eucosniius. 7.18 mm.

Hourglass Sta. C 2r 37 N. S3' 28' W. depth 37 m. FSBC 1 2284; 7. same, lateral view; 8. F. amphiurgus, hiilvti/jje. li mm, USNM

508725; 9. F. hal istreptus, holot ype. 80 mm, USNM 93333.

siphonal canal; one or two small teeth at inner,

posterior portion of parietal callus, obsolete in

largest shells; inner surface of outer lip with

14-18 simple, usually paired lirae or teeth. Base

and anterior siphonal canal slender, about half

total length of shell. Operculum thick, rough, cor-

neous, of same size and shape as aperture. Shell

white, commonly stained gray posteriorly.

Holohjpe: Length 102.0 mm. Gulf of Mexico off

Sarasota, Florida, 183 m (USNM 749082).

Other material: 3 paratypes, 42.9-84.9 mm,

west of Dry Tortugas, 183 m (FSBC I 15028); 1

paratype, 97.0 mm, same data (BMNH 197810); 1

paratype, 80.0 mm, same data (MCZ 288494); 1,

65.5 mm, west of Sarasota, 183 m, Withrow colln.;

4, 57.9-92.4 mm, south of Dry Tortugas. 375 m,

Withrow colln.; 1 paratype, 70.4 mm, southwest

of Rgmont Key, 76 m [?; depth probably actually

about 200 m] (ANSP 345472); 1 paratype, 97.9

mm, same data (AMNH 183874); 87.0 mm, same

data, Hepler colln.

Etymology: The species is named in memory of

the late Daniel D. Steger, Tampa, Florida, whose

early dredging and study of Gulf of Mexico mol-

lusks stimulated much of the present interest in

this fauna.

Discussion: Fksinus stegeri is distinguished

from the similar F. eucosmius (Dall, 1889)

(Fig. 6) by its larger size, possession of more

numerous ribs on anterior whorls, and white col-

or. Color of living or freshly dead F. eucosmi^is

shells is orange or apricot, with strongest pigmen-

tation in intercoastal areas. Fusinm eucosmius

attains a maximum length of approximately 86

mm, but specimens larger than 80 mm are un-

common. At maximum size, F. ettcosmius has

eight or nine strong axial ribs on the terminal

(usually eleventh) whorl. Axial ribs increase with

shell size throughout the development of F.

Vol. 92

April 27, 1978

ITie Nautilus 87

eucosmius. the final rib on the terminal whorl be-

ing far larger than any other rib on the shell

(Fig. 7). Conversely, axial ribs on later whorls

of F. stegeri are markedly smaller than those on

some intermediate whorls (Figs. 2, 5). The in-

ner lip, an extension of the parietal shield and

columella, is usually very well developed on large

F. stegeri^ and may be present on specimens as

small as 70.4 mm (ANSP 345472), but I have seen

shells as large as 84.9 and 87.0 mm (FSBC I

15028; Hepler colln.) with no inner lip develop-

ment. On shells of similar length, apertures are

placed more posteriorly on F. stegeri than on F.

eucusm ius.

Bathymetric ranges of F. encosmius and F.

stegeri are apparently separate. Dall (1889)

reported F. eucosniiuii at eight stations, seven of

which ranged in depth from 27 to 73 fms (49-134

m) and actually contained the reported species. I

have since seen F. ev£osmi2/s dredged in 89

fms (162 m) off Key West by Henderson (USNM

414794). However, Ball's other station, from 111

fms (203 m) off west Florida, contained two small

specimens of F stegeri, which Dall labeled F.

eucQsmius var. (USNM 93650). I have seen addi-

tional specimens labeled as being captured from

depths of approximately 100-205 fms (183-375 m),

all from off the Florida west coast between Cape

San Bias and Dry Tortugas, and even one lot

labeled "250 ft" (76 m); all specimens were

originally dredged by Mr. Riley Black, Ft. Myers,

Florida, who told me the species was most com-

mon in depths of 100-110 fins (183-201 m) and

was never collected in 250-ft. depths.

Specimens of Fxisiniis stegeri are common in

the cabinets of many shell collectors who have ob-

tained unsorted deep water dredgings from the

eastern Gulf of Mexico. The shells are usually er-

roneously identified as F. eucosmius, F. am-

phiutyus (Fig. 8) (Dall, 1889), or F. haiistreptus

(Dall, 1889). Differences between the new species

and F eucosmius have been discussed. Fusinus

amphiui-gus (Fig. 8) is a small species possessing

eight whorls in a length of 14 mm and colored

yellowish, with sprial touches of reddish brown;

it is clearly not the new species. Fusinus

halistreptm (Fig. 9) is similar to F. stegeri.

but possesses only very low, rudimentary ribs

and occurs at greater depth; I have seen only the

holotype (USNM 93333) ft-om 338 fins (609 m)

near the Little Bahama Bank.

Other names validly or otherwise applied to

living western Atlantic Fusinus species include:

aepynotus, alcimtis alcimus, alcimus rushii,

amiantus. and benthalis, all Dall, 1889, hremlien-

sis Grabau, 1903, bullatus Dall, 1927, ceraniidus

Dall, 1889, closter Philippi, 1850, couei Petit,

1853, doumnus Olsson, 1954, caboblanquensis

Weisbord, 1962, frenguellii Carcelles, 1953,

gradntus Reeve, 1848, hartvigii Shuttleworth,

1859, helenae Bartsch, 1939, marensis Weisbord,

1962, marmoratus Philippi, 1846, schrammii

Crosse, 1865, sinistralis Lamarck, 1816, spertrurn

Adams and Reeve, 1848, strigatus Philippi, 1851,

timessm Dall, 1889, and vitreus Dall, 1927. Some

of these have since been shown to belong to

faunas of other oceans, others are not species of

Fusinus. and some may be synonyms of still

othere on the list. All were eliminated as possible

names of the new species.

Early whorls of F stegeri are usually

somewhat eroded and stained gray, as often oc-

curs on gastropods living at the outer continental

shelf edge or upper slope. However, several

.specimens are sufficiently intact to reveal that

axial sculpture occurs only on approximately the

last half whorl of the protoconch, indicating the

species should be assigned to Fusinus s.s. Abbott

(1974) included F. eucosmius, F. couei, and F.

helenae with F. timessus and F. doumnus in the

subgenus Heilprinia Grabau, 1904, but embryonic

sculpture of the first three species clearly dictates

their placement in Fusinus s.s.: the last two

species, with strong axial riblets on all embryonic

whorls, are properly Heilprinia. Abbott's specula-

tion that F. doimanus might represent only a

southern subspecies of F. eujcosmius is therefore

incorrect.

ACKNOWLEDGMENTS

Mr. Carl Withrow, St. Petersburg, Florida,

donated the specimen selected as holotype of the

new species. Messrs. Jerome Bijur and Robert

Grab, Naples, Florida, and Neil Hepler, Deerfield

Beach, "Florida, also donated specimens from their

TTie Nautilus

April 27. 1978

Vol. 92 (2)

collections. Dr. K. J. Boss, Museum of Com-

parative Zoology, provided information on the

holotype of Fusinus amphiurgus. Mrs. Sally D.

Kaicher, St. Petersburg, provided illustrations of

holotypes of F. (iitiphiunjux and F. halistrcjjtns

and photographed the other specimens. Mr. Riley

Black, Ft. Myers, Florida, provided information

regarding initial specimen capture. All are

gratefully thanked.

LITERATURE CITED

.Abbott. R. T 197-1. Amcncaii Seaxhetls. 2nd ed. 6&3 pp.. 24 pis.

Van Nostrand Reinhold C«.. New York.

Dall, W. H. 1889. Reports on the results of dredging, under

the supervision of Alexander Agassiz. in the Gulf of Mexico

(1877-78) and in the Caribbean Sea (1879-80), by the U. S.

Coast Survey steamer Blake. Lieut. Commander C. D.

Sigsbee. U.S.N., and Commander .1. R. Bartiett, U.S.N., com-

manding. XXIX. Report on the Mollu.sca. Part 2. Gastropoda

and Scaphopoda. BdL Mus. Comp. Zool. 18: 1-192, pis. 10-40.

A NEW FOSSIL ASHMUNELLA (PULMONATA:POLYGYRIDAE)

FROM THE SIERRA DIABLO AND HUECO MOUNTAINS, TEXAS

Artie L. Metcalf

Department of Biological Sciences

University of Texas at El Paso

El Paso, Texas 79968

and Richard W. Fullington

Dallas Museum of Natural History

Fair Park Station

Dallas, Texas 75226

ABSTRACT

A new species of fossil pohjfii/rid land snail. Ashmunella watleyi, r.s described.

The species has been found in deposits of probable lute Pleistocene age in the

Sierra Diablo and Hueco Mountains of western Texas. An associated molluscan

fauna is reported and paleoecological implications discussed.

Extreme western Texas is located in the Basin

and Range Physiographic Province. Some "ranges"

may be no more than uplifted plateaus be-

tween lower-lying basins. Such is the Diablo

Plateau, located mainly in Hudspeth County,

Texas. It is bordered by the Salt Basin on the

east and Hueco Bolson on the west. Fenneman

(1931: 395) characterized the area thus: "Near the

Texas boundary there rises. . . the Diablo

Plateau. . . bounded by faults and sloping

eastward. . . The dissected fault scarps on both

sides appear as mountains when viewed from the

biusins. That on the west, 2,(KK) ft. high, is known

as the Hueco Mountains and farther south as the

Finlay Mountains. The somewhat lower scarp on

the east is the Diablo Range." The fossils treated

herein are from the Sierra Diablo (Fenneman 's

"Diablo Range") and the Hueco Mountains. The

bedrock of both ranges is predominantly lime-

stone of Permian age.

The fossiliferous deposits at the type locality

(Loc. 1. described at end of paper) occur on an

east-facing slope in the upper end of the main,

south arm of Victoria Canyon, which debouches

eastward into Salt Basin. The deposits are of

sharply angular limestone rock rubble, derived

from the Permian bedrock of the area, with in-

terstices filled with silts of rock color "Moderate

yellowish -brown, lOYR 5/4." The rubbly deposit

fomis a mantle on the lower part of the slo{)e.

Eleven species of gastropods have been taken

from this deposit, including an A.'<hnuinclln

judged to be new. From the Hueco Mountains on-

ly one specimen of Ashmunella has been taken at

each of two localities (Locs. 2 and 3). The,se .shells

also were obtained from deposits of hillslojie col-

luvial mantle.

Ashmunella watleyi new species

(Figs. 1-1)

Description of Holotype: Shell moderately

Vol. 92 (2)

April 27, 1978

TTie Nautilus 89

thick, 12.5 mm in diameter and 5.35 mm high;

moderately depressed with spire forming angle of

145°; angular peripherally with angulation at %

height of body whorl: body whorl not descending;

umbilicus narrow, 2.1 mm wide and contained

5.95 times in diameter of shell; aperture oblique-

ly oriented at angle of 60° to vertical, 3.5 mm

high and 3.8 mm wide. Peristome thickened,

lamellar and distinctly raised above subtending

body whorl surface on parietal wall and forming

callus in outer lip. Parietal peristome bearing

two denticles: (1) a single, much larger, obliquely

oriented lower tooth, 2.3 mm long and 0.6 mm

high, bearing a short ventroposteriorly inclined

"tail" below: (2) an upper tooth oriented horizon-

tally, scarcely more than an elongate swelling, ca.

0.6 mm long and not joining the lower tooth pos-

teriorly. Callus of outer lip subtending three den-

ticles: (1) uppermost (palatal) denticle subrec-

tangular with straight outer margin, 1.4 mm long

and rising 0.45 mm above lip callus, separated by

0.7 mm from middle tooth; (2) middle tooth peg-

like, 0.7 mm wide, rising 0.6 mm above callus and

separated by 0.75 mm from lowermost (basal)

tooth; (3) basal tooth rounded and oriented obli-

quely on callus, 1.4 mm long and rising 0.6 mm

above callus. Outermost one mm of lip reflected

FIGS. 1-4. Ashmunella watleyi new species: 1, 4. Holotype

(12.5 mm. diameter); 2, 3. Paraiype (13.5 mm, diameter)

from hoc. .1. Huecii Mts. 5. Ashmunella carlsbadensis l^hhni

(U.75 mm. diameter) from northern Sierra Diablo (mentimed

in text)

back over body whorl. Number of whorls, 5. Nu-

clear 1.5 whorls smooth; upper surface of suc-

ceeding whorls bearing weak growth lines, these

becoming stronger on body whorl. Upper surface

of whorls two and three bearing many short,

slightly raised papillae, parallel to growth lines

(see below). Lower shell surface generally smooth

with some weak growth lines, these stronger near

lip.

The papillae noted above seem to give evidence

of the presence of cuticular scales on at least part

of the dorsal surface of the shell in life. They

greatly resemble those described by Clench and

Miller (1966: 2) for Ashmunella beqvaerti: "In

older specimens where the scales have worn off,

there remain raised hyphen-shaped papillae,

parallel to the growth striae, giving a granular

appearance to the surface."

This species is named in honor of Mr. Ray

Watley, Texas Parks and Wildlife Department,

who hospitably escorted us to and on the Sierra

Diablo Wildlife Management Area, which con-

tains the type locality (Locality 1, described

hereafter).

Holotype, Delaware Museum of Natural

History 118338. Paratypes: Dallas Museum of

Natural History 5359; University of Texas at El

Paso 3638, 4375 and 4978.

Variation: Only eight measurable paratypes

were recovered from Loc. 1. For these the follow-

ing measurements (in mm) and proportions were

obtained (mean outside parenthesis; range inside

parenthesis): Diameter: 12.94 (11.2-14.2); Height:

5.2 (4.75-5.6); Width of Umbilicus: 2.53(2.1-2.9);

Length of Lower Parietal Tooth: 2.26 (1.8-2.6);

Length of Palatal Tooth: 1.64 (1.5-2.0); Number

of Whorls: 4.99 (4.85-5.2); Diameter/Height: 2.44

(2.36-2.54); Diameter/Width of Umbilicus: 5.14

(4.48-6.14).

Among specimens from Loc. 1 there is little

variation in shells. The sculpture of raised

papillae is not observable on most of these shells

probably because of exfoliation. The upper

parietal denticle is barely discernible in some

specimens. One specimen (11.2 mm in diameter),

although seemingly mature, is notably smaller

than the others and also exhibits stronger growth

lines.

90 The Nautilus

April 27, 1978

Vol. 92 (2)

Specimens from the Hueco Mountains (Ivors. 2

and 3) have the size, shape and shell texture of .4.

watleyi. Minute papillae are barely discernible on

the upper surface of the shell on whorls two and

three. They differ slightly from specimens from

Loc. 1 in denticulation, having a longer and

higher upper parietal tooth and a more slender

middle tooth in the outer lip (Figs. 2, 3).

Similarities seem great enough to provisionally

assign the few specimens from the Hueco Moun-

tains to A. watli'ifi. Po.ssibly .4. iviitlri/i is a

species that occupied, at least during late

Wisconsinan time, much of the escarpment that

bounds the Diablo Plateau on the east, south and

west. Few collections of Quaternary fossil

gastropods have been made in this area, however.

COMPARISONS

Fullington has collected living Ashmunelln in

the northern part of the Sierra Diablo ca. 22 km

north of Ijoc. 1, immediately south of Apache

Canyon on the Puett Ranch, This species seems

to be /I. carlsbadensis Pilsbry, known otherwise

from the Guadalupe and Delaware Mountains on

the east side of Salt Basin. Shells of this species

(Fig. 5) differ from those of A. watleyi in being

thinner and relatively flatter. They are carinate

rather than angular and the outer lip teeth are

all relatively smaller, the palatal tooth being

markedly narrow. Ashmunplla carlabadensis lacks

cuticular scales, which seem likely to have been

present in A. watleyi. Humboldtiana ultima

P'ilsbry, a land snail otherwise known only from

the Guadalupe Mountains, also occurs with A.

carhbadenins in the northern Sierra Diablo.

Ashmunella watleyi is larger, more depressed

and less ribbed than the fossil species,

Ashmunella nana Metcalf and Fullington, from

the Guadalupe Mountains. On the other hand, .4.

watleyi is smaller than the subspecies that have

been ascribed to A. kochii Clapp from the

Guadalupe and Cornudas Mountains. These latter

species also have a broader umbilicus and lack

the cuticular scales that were probably posse,ssed

hy A. ii'atleifi.

Cuticular scales are found in A. pasoni.<<

pasonvi (Drake) of the Franklin Mountains, west

of the Hueco Bolson and in A. bequaerti Clench

and Miller of the Davis Mountains, southeast of

the Sierra Diablo. However, both these latter

species are more depressed, more strongly keeled

and have larger denticles thatn those of ,4.

^mtleyi.

It is probable that A. watleyi and the other

species mentioned above all belong to a group of

Ashmunellas of the mountains of southern New

Mexico and far western Texas that was referred

to as the Ashmunella meaiiisi group by Pilsbry

(1940: 972) and Metcalf (1973: 39). However, af-

finities of A. watleyi within this group are not

clear.

ASSOCIATED FAUNA AND

PALEOECOLOGICAL IMPLICATIONS

In addition to A. watleyi. the following ten

species of gastropods were found in the colluvium

at Loc. 1: Gastrocopta pellucida (Pfeiffer), G.

pilsbryana (Sterki), Pupilla blandii Morse, P.

iionorana (Sterki), Vallonia perifpectiva Sterki,

Suceinea sp., Vitrina pellucida akv^kana Dall,

Hawaiia minuscula (Binney), Retinella

(Glyph iinlima) indentata paiicilirata (Morelet)

and EucDtudufifulnis (Miiller).

We searched for living gastropods on the steep

east-facing scarp of the Sierra Diablo at two

places on the Wildlife Management Area and

found only Gastrocopta pellucida and Retinella i.

paucilirata. It is likely, however, that Hairaiia

minuscula and the succineid also occur in the

area. However, the remaining species found in

the colluvium probably no longer occur in the

range, although they do occur at higher, more

mesic elevations in the Guadalupe Mountains,

across Salt Basin to the northeast. Thus, a life

zone depression is inferred, such as often has

been discerned in regard to glacial-age faunas of

the southwestern United States. It is deemed ex-

tremely likely, then, that the sediments were

deposited during a glacial-equivalent time with

colder temperatures and more effective moisture

than at present. This is borne out by the nature

of the sediments, containing, as they do, rock rub-

ble of the kind produced by frost action and not

being produced at these elevations today. As

there has been relatively little subsequent deposi-

tion and as sediments are not indurated, it seems

Vol. 92 (2)

April 27, 1978

The Nautilus 91

likely that they were deposited no longer ago

than during the late Wisconsinan (Woodford ian)

Glaciation.

LOCALITIES OF COLLECTIONS

1. Texas, Culberson Co.. 81° 17' 25" N; 1(14° 54'

47" W. Sierra Diablo Wildlife Management Area,

Texas Parks and Wildlife Department. Upper end

of main, south branch of Victoria Canyon on west

wall of canyon, co. 300 m east of Hudspeth-

Culberson counties boundary along trail leading

northward from Area headquarters buildings and

2.09 km north of these, 1660 m elevation. 12

September 1976.

2. Texas, Hudspeth Co., 31° 52' 21" N; 105° 59"

W. Hueco Mts., on west slope of Alacran Mt., 3.5

km north of Hueco Inn. 1585 m. elev. Collected by

Ronald Simpson, 7 March 1975.

3. Texas, El Paso Co., 31° 56' 30" N; 106° (K)' 7"

W. Hueco Mts., on east-facing hillslojx", 4.2 km

ENE of Hueco Tanks State Park Headquarters.

1478 m elev. 15 February 1973.

LITERATURE CITED

Clench, W. J. and W. B. Miller. 1966. A new species of

Ashmunelta from West Texas (Mollusca: Pulmonata).

Bremm-a Mus. Comp. Zwil 244: 1-6.

Fenneman, N. M. 1931. Physdngraphy of weMern United

Stiitiv. McGraw-Hill Book O)., New York, i-xiii -I- !^'M p.

Metealf, A. L. 197.3. New fo,ssil Ashmunellas from New Me.\ico

(Ga-stropoda: Pulmonata: Polygvridae). TTjc Vrliijcr 16:

31-39.

Pilsbry, H. A. 1940. Land Mollusca of North America (North

of Mexico). Acad.. Nat. Set. Phikuklphia Momiyr. 1(2): vi -I-

.S7.5-994.

MOLLUSKS WITH INDO-PACIFIC FAUNAL AFFINITIES IN THE

EASTERN PACIFIC OCEAN

William K. Emerson

Department of Invertebrates

American Museum of Natural History

New York, New York 10024

ABSTRACT

Foriy-one fipecies of prosohmvch gastropods and seven species of bivalves that

have Indo-Pacific faunal affinities are recorded from the eastern Pacific Ocean. The

vast majority of these taxa (79%) are known in eastern Pacific waters only from

the offshore islands, namely: Clipperton (38 tam). Renilla.gigedo (6 tarn), Cocos (U

taxa). Ckilapagos (9 taxa), and Guadalupe (1 taxon). Ordy 10 of these taxa are

known to occur on the continental shelf of the west American Borderland, in-

cluding the Tres Marias Islands. The fossil record proindes little direct evidence to

document the biogeography of this faunal element in the New World tropics.

A considerable amount of new zoogeographic

and geologic data has become available since I

presented a lecture on this subject to the

Eleventh Pacific Science Congress at Tokyo,

•Japan, in 1966 (Emerson, 1967). The purpose of

this paper is to update the list of the Indo-Pacific

molluscan species occurring in the tropical

eastern Pacific and to review briefly the tem-

poral significance of this faunal element in the

New World tropics.

The presence of a minor element of the modern

Indo-Pacific Faunal Province has been long

92 The Nautilus

April 27, 1978

Vol. 92 (2)

recognized in shallow water benthonic faunas of

tropical western America, the Panamic Faunal

Province {cf. Ekman, 1953 and Briggs, 1974).

Separated from the nearest Central Pacific

islands by some 3100 miles of open ocean, the

Panamic Province extends from near the head of

the Gulf of California, Mexico, southward to north-

ern Peru. Nearly 3400 species of mollusks,

representing all the extant molluscan classes, are

known from these waters (Keen, 1971).

Within the large Panamic fauna, only 48

species of the prosobranch gastropods and the

bivalves are recognized as having Indo-Pacific

faunal affinities. Constituents of this small Indo-

Pacific element are restricted to the offshore

islands, except for the rare occurrences of 10

species on the continental shelf from Mexico to

Ecuador (Table 1). The presence of an Indo-

Pacific element in the Panamic Faunal Province

is in sharp contrast to the apparent absence of

Panamic faunal elements in the Indo-Pacific

Faunal Province (Emerson, 1967).

THE INDO-PACIFIC FAUNAL

ELEMENT

The present tabulation of the Indo-Pacific ele-

ment is limited to the prosobranch gastropods

and the bivalves (Table 1). The gastropods (41

species) greatly outnumber the bivalves (7 spe-

cies). All inhabit shallow water and are epifaunal

species, with the exception of one species of

bivalve.

Many of the gastropods represent groups with

larval forms that can remain in the plankton for

long periods of time, as much as ten months

(Robertson, 1964; Scheltema, 1966, 1968, 1972;

Thorson, 1961). Of the bivalves, seven are at-

taching or boring forms; one, Codakia thaanitmi.

is the sole infaunal species. Nearly all of these

mollusks potentially are capable of being trans-

ported over vast distances of open water in the

form of drifting larvae, or by the attachment of

eggs, larval or adult forms to floating debris.

These dispersal mechanisms have been postulated

as the primary vehicle to account for the pres-

ence of the Indo-Pacific element in the modern

Panamic fauna.

In the more than 40 years since Hertlein (1937)

critically reviewed the composition of this Indo-

Pacific element, the known species representing

this faunal element have quadrupled in number,

and the verified records of these species living on

the continental shelf has increased from one to

ten. Despite recent advances in the knowledge of

the paleogeography of the New World tropics, the

fossil record still provides limited data on the

origins of this faunal element.

PALEOGEOGRAPHY

The small Indo-Pacific faunal element in the

Panamic Province (Table 1) is generally believed

to have been the result of rather recent introduc-

tions, whereas the minor element of essentially

circumtropical species (Table 2) in the west

American tropical waters is thought to represent

relict elements dating from late Tethyan faunas

(cf. Keen. 1971, p. 2; Olsson. 1972). Unfortunately,

there is little direct evidence to substantiate

these biogeographical conclusions. The only Re-

cent Indo-Pacific species recognized as fossils in

West American deposits are Cypraea cemica

Sowerby in Pleistocene terrace deposits on

Guadalupe Island (Kellogg, 1976) and possibly

Conus tessvlatm Bom (described as C. bramkam-

pi Hanna and Strong, and compared by Hanna

(1963) to C. tessuiatus) from the late Pliocene of

Imperial County, California.

The oldest of the offshore islands based on

fossil evidence are in the Galapagos archipelago,

where Pliocene (Hertlein, 1972) and late Miocene

(Durham & McBirney, 1975) mollusks are known.

The meager geological evidence suggests that the

other offshore islands are young, probably

Pleistocene in age (Emerson, 1967). As all of the

offshore islands, e.xcept the Tres Marias, are on

submerged ridges or on fracture zones, one can-

not ignore the possible existence of formerly

emergent islands on these topographic structures

that may have served as temporary dispersal

bridges. The modern Galapagos Islands, for exam-

ple, are interpreted by Holden and Dietz (1972)

as the most westerly emergent remnants of a

volcanic chain of which the most easterly com-

ponents have subsided. They postulate that a

series of ancestral "Galapagos Islands" may have

existed over a span of 40 million years and thus

Vol, 92 (2)

April 27, 1978

The Nautilus 93

TABLE 1. iMoUuscs with Indo-Paeific faunal affinities (ex-

clusive of Opkthohranchs) occurring on the west coast of the

New World and the offshore islands, hosed on numbered

West American Mainland

Gastropoda

Conns ebraeus Linnaeus - 1, 6, 11, 18, 19, 21, 28

Gimis tessulatus Bom - 19, 21, 25

Cifpraea teres Gmelin - 4. 9, 19, 21, 27, 29

Heliacus trochoides (Deshayes) - 21

Micrndaphne trichodes (Dall) - 19, 21

Mitra mitra (Linnaeus) - 24. 27

Quoifida madreporarum (Sowerby) - 5, 13, 18, 19, 21, 27

Terebra affinis Gray - 2, 19, 21

Terebra laeirigata Gray - 19, 21

Titiscania limacina (Bergh) - 19, 21

Galapagos Islands

Gastropoda

Conu£chalde2is (RSding) - 1, 11, 12, 13. 19

Comis ebraeus Linnaeus - 1, 6, 11, 12, 13. 19

Coralliophila neritoides (Lamarck) - 8, 19

= C Wo/acea (Kiener)

Cifpraea moneta Linnaeus - 4, 8, 1,3, 19

Cypraea teres Gmelin - 4, 8, 9, 19

Drupa ricinus (Linnaeus) - 10, 13

Microdaphne trichodes (Dall) - 19

Mitra mitra (Linnaeus) - 24, 26

Psendocypraea adamsoni (Sowerby) - 8, 19

Clipperton Island

Gastropoda

Bursa gramdaris (Roding) - 16, 18, 19, 23

Conus chaldeus (Roding) -1,11, 12. 13, 18, 19, 23

Conns ebraeus Linnaeus - 1, 6, 11, 12, 13, 18, 19, 23

Comis tessidatus Born - 15

Cvrallwphila neritoides (Lamarck) - 8, 16. 19, 23

= C violacea (Kiener)

Cypraea depressa Gray - 4, 13, 15, 18, 19

Cypraea maculifera (Schilder) - 4, 15, 19

Cypraea scurra indica Gmelin - 4, 13, 15, 18, 19

Cypraea capntserpentis Linnaeus - 4, 15, 19

Cypraea moneta Linnaeus - 4, 15, 19

Cypraea helvola haimiiensis Melvill - 4, 1.5, 19

Cypraea rashleighana Melvill - 4

Cypraea arenosa Gray

=C schilderorum (Iredale) - 4, 15, 19

Cypraea teres Gmelin - 4, 8, 9, 13, 15, 18, 19, 23

Cypraea vitellus Linnaeus - 4, 15, 19

Diodora granifera (Pease) - 17, 19

Drupa morum Roding - 10, 16, 23

Druparicinus (Linnaeus) - 10, 13, 16, 18, 19. 23

Harpa gracilis Broderip & Sowerby - 16, 20 23

references in Literature Cited, and on: 25:-CM. A.M.N.H.

(Panama); 2A:-Coll. Darwin Research Station, (hlapagos

Littmina pintado .ichmitti Bartsch & Rehder - 16, 18, 19. 22,

23 (an endemic subspecies)

Magilus robillardi IJenard - 16, 18, 23

Mitra edentula Swainson - 16, 23

Mitra ferruginea Lamarck - 16, 23

Mitra papalis (Linnaeus) - 13, 16, 18, 19. 23

Morula uva (Roding) - 13. 16. 18. 19

=M aspei-a (Lamarck)

Nassafrancolinus (Bruguiere) - 16. 23

Nerita plicata Linnaeus - 16, 18, 23

Quoyida madreporarum (Sowerby) - 16

Strigatella litterata Lamarck - 23

Terebra cremdata interlineata Deshayes - 16

Peristemia thaanumi Pilsbry & Bryan - 17

Cerithium nesioticum Pilsbry & Vanatta - 17. 19

Bivalvia

Acarc/flaysana Dall, Bartsch & Rehder - 17

Spondylus hauniensis Dall. Bartsch & Rehder - 23

Spondylus gloriosus Dall. Bartsch & Rehder - 17, 19, 23

Hyotissa hyotis (Linnaeus) - 17, 19, 23

Codahia thaanumi Pilsbry - 17, 23

Martesia striata (Linnaeus) - 17

Revillagigedo Group

Gastropoda

Conus tessidatus Born - 11. 12. 18

Coralliophila neritoides (Lamarck) - 8, 19

Hastula albula (Menke) - 2, 3, 19

Qiwyida madreporarum (Sowerby) - 13, 18

Terebra cremdata (Linnaeus) - 2, 3, 19

Terebra maculata roosevelti Bartsch & Rehder - 2, 3, 19

(an endemic subspecies)

Cocos Island

Gastropoda

Cypraea moneta Linnaeus - 4, 7, 8, 13, 14, 19

Cypraea rashleighana Melvill - 4, 8, 14. 19

Terebra macnlata macvlata (Linnaeus) - 2. 3, 7, 19

Bivalvia

Isognomon qitadrangularis (Reeve) - 7, 14

Guadalupe Island

Gastropoda

Morula uva (Roding) - 19

Tres Marias Islands

Gastropoda

Qimyula madrepon-amm (Sowerby) - 19

94 The Nautilus

April 27, 1978

Vol. 92 (2)

TABLE 2. Trtipicopolitan gastropods (exclusive of

Ol/ixth(ihmiirhs) known to occur in the western Atlantic ami

western Pacific as well as on the west coast of North and

Central America and the offshore itlands, based on:

X-Emerson and dd, 196S: 2-Emerson and Old, 196i:

3-Hertlein. 19:i?; i-Hertlein and Allkon. 1960b: 5-Ke.en. 1971:

6-Raduin. 1969: IStrony and Hertlein. 19S9. Excluded are

tropical superspecies with Mopatric populations in the

western and eastern Pacific and the westen Atlantic thai are

presently recognized as distinct species: e.g.: Casmaria

erinai'eiis (Linnaeus). C. vibexmexicana (Steams), and C.

atlantica ((Tench).

Mainland of Central America

Cheilea equestris (Linnaeas) - 3, 5 (a.s ('. cepacea Broderip)

Crepidula aodeata (Gmelin) - 3. 5. 7

Ci/tnatium parthenopeum (von Salis) - 1. h {as C. p. keenae

'Beu)

Ciimatimn pileare (Linnaeus) - 1. -T

HipiKinix antiqiuitits (Linnaeus) - 3, 5 (as H. panamensis C. B.

Adams)

Galapagos Islands

Oieilea equestris (Linnaeus) - 3

Crepidula aculeata (Gmelin) - 3

Cymaiium parthenopeum (von Salis) -1, 5 (as C. p. keenae

Beu)

Cj/malium muridnum (Ro'ding) - 6

Hipponyx anliqwdus (Linnaeus) - 3

Gipperton Island

Ci/tnatium nicobarirum (Roding) - 4

Ci/nifitumi pileare (Linnaeus) - 1

Hipp(mifi anliquatus (Linnaeus) - 4

Revillagigedo Group

Crepidula aculeata (Gmelin) - 3

Cymatium pileare (Linnaeus) - 1

Cocos Island

Cifmatium pileare (Linnaeus) - 2

provided for the isolation necessary to evolve the

many endemic terrestrial organisms found on the

present Galapagos (cf. Shields, 1976: 51). By their

model, animals would have negotiated a short

span of water to a new volcanic island as an

older extinct volcanic island drifted eastward and

became submerged and attached to the end of the

Cocos and Carnegie ridges. They concede that no

guyots are known from either the Carnegie or

Cocos chains, but stress there is no evidence to

preclude that these ridges were not subaerial at

some time in their history.' As Rosen (1975)

' An assemblage of invertebrates of probable Mi<x^ene age was

dredged from a guyot at a depth of 227 meters on the Nasca

Ridge, located to the south and fronting the peru Trench.

HermatjTJic corals in the sjimple suggest a tropical, shallow-

water habitat (Allison, et al.. 1967).

points out, this view is in sharp contrast to the

Darwinian concept of the Galapagos as oceanic

islands, which could not have been historically

connected to the mainland. Moreover Holden and

Dietz conceive the Galapagos as emergent out-

posts of an ancient Cocos-Carnegie ridge system,

the eastern part of which is subsiding, and is be-

ing consumed by the Cordilleran Trench system

of the South American plate. Indeed, the lack of

preservation of fossilferous marine Tertiary

deposits in much of the middle west American

Bfjrderland largely limits paleogeographic inter-

pretations of the faunistic history of the modern

Panamic Province to the regional Pleistocene

record and to comparisons with the Tertiary

record of the adjoining faunistic regions.

The Tertiary Caribbean Province, as defined by

Woodring (1966; 1972) based largely on Mio-

Pliocene molluscan faunas, included parts of the

modern Caribbean and Panamic provinces. It ex-

tended from the r^ion of Tampico, Me.xico, to

northern Brazil in the western Atlantic, and

from southern Nicaragua to northern Peru in the

eastern Pacific. The northwest limits of the Ter-

tiary province in the eastern Pacific cannot be

determined because no marine deposits of Ter-

tiary age are recorded from southern Nicaragua

to Baja California, Mexico, a stretch of 3,000

kilometers. Presumably most of these sediments

have been lost by subduction into the Middle

American Trench system. The deficiency of the

Tertiary record from this part of west America

has invited faunal comparisons with the better

preserved Tertiary faunas of the Caribbean re-

gion in attempting to determine the faunal af-

finities of the modern Panamic Province. As a

result, taxa that survive in the western Pacific,

but are not known to be living or as fossils in the

eastern Pacific and also occur in the modern or

Tertiary faunas of the Caribbean region, are con-

sidered to represent largely Tethyan relicts that

reached the Caribbean Province by migration

across the Atlantic Ocean. On the other hand, lar-

val dispersal into eastern Pacific waters from the

Caribbean region before the closure of the trans-

American seaways in the Pliocene is suggested by

the apparently earlier occurrence in the western

Atlantic than in the eastern Pacific for most of

Vol. 92 (2)

April 27, 1978

Tlie Nautilus 95

the taxa comprising the Caribbean Tertiary Pro-

vince, and by the presence of numerous closely

related "twin species" separated by the Panama

Land Bridge in the modern Panamic and Carib-

bean provinces. There is a small element in the

Caribbean Tertiary Province for which the ear-

liest fossil record is in the eastern Pacific and an

even larger element which has essentially a con-

temporaneous appearance in both the eastern

Pacific and the Caribbean regions of the Tertiary

Province (Woodring, 1965, 1966; Yokes. 1976).

Owing to the incompleteness of the fossil record

of the west American Borderland and to gaps in

the fossil record in the western Atlantic, the

origin of these elements can not be determined

on the basis of paleontological evidence. They

may well have been represented earlier in the

eastern Pacific than in the western Atlantic.

These tropical elements, however, have not been

recognized in the fossil record of western North

America, with the exception of a few warm-water

ta.xa in the Miocene of central California and the

tropical taxa persisting in the Pliocene of

southeastern California and the Gulf of Califor-

nia (Keen, 1976). The presence of these faunal

elements in the "Pacific Outposts of the Tertiary

Caribbean Province," to use Keen's appellation,

requires a paleogeographic reexamination of

these faunas. Futhermore, as Rosen (1975) has

stressed in proposing a vicariance model of Carib-

bean biogeography, ". . . fossils give a minimum

age rather than a maximum age for the groups of

which they are members." Because of the limita-

tions of the fossil record and the failure to ap-

preciate fully the influence sea-floor spreading,

plate tectonics and continental drift has had on

the alteration of shorelines and oceanic current

systems, a seemingly overly simplistic paleogeo-

graphic model has been inferred for the tropical

faunas of the New World Tertiary.

ACKNOWLEDGMENTS

I thank Warren 0. Addicott, J. Wyatt Durham,

David R. Lindberg, Malcolm C. McKenna, Michael

G. Kellogg, James H. McLean, Gareth J. Nelson,

and William J. Zinsmeister for contributing data.

William E. Old, Jr. kindly provided technical

assistance.

LITERATURE CITED

Some references in thi.s article have been numbered in

order to serve as a convenient guide to literature sources

quoted in Table 1.

(1) .\llison, E. C. 1959. Distribution of (hnun on Qipperton

Island. yWiyo- 1(4): .32-34.

Allison, E. C, J. W. Durham, and L. W. Mintz. 1967.

New southeast Pacific echinoids. Calif. Amd. Sci

Occ. Papers, no. 62, 23 pp. ; .32 figs.

(29) Bakus. G. J. 1968. Quantitative studies on cowries

(Cypraeidae) of the Allan Hanctxik Foundation col-

lection. Ke/j^rr 11(2): 93-96.

(2) Bratcher, T. 1970. Range extensions of Indo-Pacific

Terebra. Hawaiian Shell News 18(3): 6, 2 text figs.

(3) Bratcher. T. and R. D. Burch. 1971. The Terebridae

(Gastropoda) of Clarion. .Socorro, Cocos, and Galapa-

gos Islands. Pi-nc. Calif. Acad. Sc.i.. ser. 4 37(21):

.5.37-5&5; 33 text figs.

Briggs. J. C. 1974. Marine zoogeography. McGraw-Hill,

New York, 47.5 pp., illus.

(4) Cate, C. N. 1969. The eastern Pacific cowries. Veliger

12(1)5 1(13-119; pis. 11-15.

Durham. -J. W. and A. R. McBimey. 1975. Galapagos

Islands. In R. W. Fairbridge. ed.. The Encyclndpedia

of World Regional Geology. Pt. 1. Dowden. Hutchin-

son & Ross. Stroudsburg, Pa. 285-290.

Ekman. S. 195.3. Zfingeography of the Sea. Sidgwick and

.Jackson. London; 417 pp; 121 t^.xt figs.

(5) Emerson, W. K. 1967. Indo-Pacific faunal elements in

the tropical eastern Pacific with special reference to

the mollusks. Venus 25(;3&4): 85-93; 1 text fig.

(6) . 1968. A record of the Indo-Pacific cone.

Comis ebraeiis. in Guatemala. Veliger 11(1): 33.

Emerson, W. K. and W. E. Old. Jr.'l963. Results of the

Puritan-American Museum of Natural History Ex-

pedition to Western Mexico. 19. The Recent Mol-

lusks: Gastropoda, Strombacea, Tonnacea, and Cyma-

tiacea. Amer. Mus. Nomtate^. no. 2153, .38 p.. 28 figs.

(7) 1964. Additional records from &)cos

Island. TheNaidilm 77(3): 90-92.

(8) . 1965. New molluscan records for the

Galapagos Islands, ne Nautilus 78{i): 116-120.

(9) , 1968. An additional record for Cypraea

teres in the Galapagos Islands. Veliger 11(2): 98-99;

pi. 12.

(10) Emerson, W. K. and W. 0. Cernohorsky. 1973. The

genus [>rupa in the Indo-Pacific. Indo-Pacific

A/n//((,9co3(13):40p.,35pIs.

(11) Hanna. G. D. 196.3. West American mollusks of the

genus C<)nus - II. C(dif. Acad. Sci. Occ. Papers, no. 35,

103 pp., 11 pis.. 4 text figs.

(12) Hanna. G. D. and A. M. Strong. 1949. West American

mollusks of the genus Conus. Proc. Calif. Acad. Sci.,

ser. 4. 26(9): 247-.322; pis. 5-10; 4 text figs.

(13) Hertlein, L. G. 1937. A note on some species of marine

mollusks occurring in both Polynesia and the

western Americas. Proc. Amer. PhU. Soc. 78(2):

303-312; pi. 1;1 text fig.

(14) 1963. (Contribution to the biogeography

of Cocos Island, including a bibliography. Proc. Calif.

Acad Sci. ser. 4, 32(8): 219-289; 4 text figs.

1972. Pliocene fossils from Baltra (South

Seymour) Island. Galapagos Islands. Proc. Calif.

Acad Sci. ser. 4, 39(3): 25-46; 39 text figs.

96 The Nautilus

April 27. 1978

Vol. 92 (2)

(15) Hertlein. L. G. and E. C. Allison. 1960a. Species of the

genus Cypraea from Qipperton Island. Veliyer 2(4):

94-95; 2 text figs.

(16) . 1960b. Gastropods from Clipperton

Island. Ve/ifler 3(1): 13-16.

(17) . 1966. Additions to the molluscan fauna

ofOipperton Island. VeHger%(2): 138-140.

(18) Hertlein. L. G. and W. K. Emerson. 195;^ Mollu.sks

from Clipperton Island (eastern Pacific) with the

description of a new species of gastropod. Trans. San

IHi'ijo Siic: Nat. Hist. 1 1(3):,34.5-364: pis. 26-27.

Holden, J. C. and K. S. Uietz. 1972. Galapagos Gore,

NazCoPac triple junction and Carnegie/Cocos

Ridges. Nature 235: 266-269; 5 text figs.

(28) Houbrick, J. R. 1968. New record of Conus ebraeus in

Costa Rica. Veliger 10(3): 292.

(19) Keen, A. Myra. 1971. Sea Shells of Tropical West

America. Stanford Univ. Press, ed. 2, xiv + 1064 p.,

illus.

. 1976. Pacific outposts of the Tertiary

Caribbean Province. Amer. Malacul. Union Bull, fur

197.5. p. 46 [abstract].

Kell(5gg, M. G. 1976. A cowrie from the late Pleistocene

of Isla Guadalupe. Mexico. Western Soc. Malacol.

Ann. Rep. 9. 43-44 [abstract].

Olsson. A. A. 1972. Origin of the existing Panamic

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