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A NEW SPECIES OF FLATFISH, MANCOPSETTA MILFORDI, FROM

SOUTH AFRICA, WITH NOTES ON THE GENUS MANCOPSETTA

M. J. PenriTH*

South African Museum, Cape Town

(With 2 figures in the text and 1 plate)

CONTENTS

PAGE

Introduction. : : : 181

Mancopsetta milfordi sp. n. . Lo

Generic grouping 5 : Ht83

Genus Mancopsetta. ; . 186

Distribution : : F F 187

Acknowledgements. : SOS

Summary : : , ; 188

References , : 5 Ba aiksks}

INTRODUCTION

The genus Mancopsetta was proposed by Gill (1881) to replace the pre-

occupied generic name Lepidopsetta used by Gunther (1880) when describing

M. maculata, the first of the bothid fishes found which lacked pectoral fins. This

species has until now remained the only species in the genus and has been

known from a very few specimens found in the Southern Hemisphere. The

related genus Achiropsetta (Norman, 1930) was known from two species, both

rare and recorded only from the Southern Hemisphere. Recently the South

African Museum was presented with two specimens of a bothid fish lacking

pectoral fins. These have been assigned to the genus Mancopsetta.

Mancopsetta milfordi sp. n.

(fig. 1, pl. ITT)

Material :

S.A.M. 24041: trawled by a commercial trawler in 300 fathoms west of Cape

Town. Standard length 393 mm. (Holotype).

S.A.M. 23767: trawled by a commercial trawler in 370 fathoms west of Cape

Town. Standard length 298 mm.

The body is compressed, sinistral and fairly elongate, the maximum depth

being about 2% in body length (excluding the caudal fin). The axial portion

of the body is thickened relative to the rest of the body in the smaller specimen,

* Seconded from the Council for Scientific and Industrial Research Oceanographic Unit,

University of Cape Town.

181

Ann. S. Afr. Mus. 48 (7), 1964, 181-188, 2 figs., 1 pl.

182 ANNALS OF THE SOUTH AFRICAN MUSEUM

but this seems to become less marked with increase in size as it is not noticeable

in the larger specimen. The caudal peduncle is very short, being only 4 of the

longitudinal diameter of the eye.

There is a single straight lateral line on both sides with about 160 scales

on the ocular side. The scales are ctenoid with normally eight to twelve spinules.

Towards the edges of the fish, especially on or near the fins, the spinules project

at an angle away from the body, but on the main trunk they lie flat. The entire

head, including the jaws and part of the eyes, is covered with fine scales. The

eyes are separated by a low, scaled, bony ridge. All fin rays, including the

caudal, have a row of scales.

The head from the tip of the maxilla to the hindermost edge of the oper-

culum is contained 4 times in standard length, while the greatest diameters

of the eyes (both eyes equal) are } the length of the head. The snout is slightly

shorter than the eye diameter. There is a small fleshy growth over the front

of the maxilla. The mouth reaches back to a point almost level with the posterior

edge of the lower eye. Teeth are present on both sides of the jaw but are

slightly better developed on the ocular side. The mouth has a very wide gape

and is protrusible. The membranes on the ocular side are more protrusible

than those on the blind side. There are nine small gill-rakers on the lower arch

of the first gill.

There is no trace of any pectoral fin on either side. The pelvic fin on the

ocular side is larger than that on the blind side. On the eyed side the anterior

base of the pelvic fin is median, while posteriorly the base is twisted to the left,

i.e. on to the ocular surface of the body (fig. 1).

The body proportions and meristic counts of the two specimens are given

in Table I and compared with a specimen of M. maculata from the collection

of the British Museum (Natural History) (Registered No. 1930.5.6: 41).

The colour, preserved in formalin, is brown-grey with the anal and dorsal

fins grey slate/blue. There is no trace of any pattern.

TABLE I

M. milfordi M. milfordi M. maculata

Total length .. ae ets a 456 334 239

Standard length ve ae 6 392 298 199

Greatest depth .. ta sa ys 143 (364) 99 (332) 88 (442)

Head length .. ae ss st IOI (258) 76 (255) 53 (266)

Length of snout she : i 22 (56) 15 (50) 10 (50)

Diameter of eye (horizontally ar 24 (61) 20 (67) 17 (85)

Interorbital width aie Rie Sc 8 (17) 5 (15) 3 (15)

Length of Maxillary .. A 48 (122) 33 (111) 18 (go)

Number of scales in lateral line =f 164 177 119

Dorsal rays Ne a > 9 130 133 119

Anal rays 3 56 ate 109 110 98

Pelvic rays, blind side .. Be “8 6 6 5

Pelvic rays, ocular side re Sc 7 7 7

Gill-rakers, lower arch ae 56 9 9 12

Body proportions and meristic counts of M. milfordi and M. maculata. Body proportions in

millimetres and in thousandths of standard length in parentheses.

A NEW SPECIES OF FLATFISH, MANCOPSETTA MILFORDI 183

Ficure 1. Head of M. milfordi showing the twisting of the posterior portion of the left pelvic fin

onto the ocular surface.

Mancopsetta milfordi differs from M. maculata in the number of dorsal and

anal rays and lateral line scales, the twisting of the posterior end of the left

pelvic fin onto the ocular surface and in certain body proportions. It resembles

M. maculata, however, in general body shape, especially head shape, and in the

type of scales.

The species is named for Mr. C. S. Milford, managing director of the

trawling firm, Messrs. Irvin and Johnson (Pty.) Ltd., in recognition of generous

support for marine biological research.

GENERIC GROUPING

According to Norman (1934) there are only two genera of bothids (both

known only from the Southern Hemisphere) which lack both pectoral fins.

184 ANNALS OF THE SOUTH AFRICAN MUSEUM

These two genera, Mancopsetia and Achiropsetta are said to differ in the following

characters... .

(a) Achiropsetta is said to have a flat scaled interorbital space, whereas

that of Mancopsetta is stated to be a naked narrow bony ridge.

(b) Achiropsetta is said to be more elongate and to have a thickened trunk.

left posteriorly as is said to be the case in Achiropsetta.

(dq) In both genera the scales are small and ctenoid, but in Mancopsetta

the 8-14 spinules lie flat, whereas in Achiropsetta there are only one

or two spinules which are directed away from the body.

These differences would seem to be clear cut, but the finding of a second

species of Achiropsetia, A. slavae (Andriashev, 1960) and the present species have

suggested that the differences between the genera are not so marked as was

formerly thought. Neither A. slavae nor M. milfordi fits completely the generic

description of the genus in which it has been placed. The distribution of various

taxonomic characters among the four species of bothids which lack pectoral

fins is shown in Table IT below.

TABLE II

Achiropsetta Mancopsetia

tricholepis slavae maculata milfordi

Dorsal rays un A ane ute 132 114-117 116-119 130-133

Anal rays 56 as =i Sic 114 93-96 97-98 109-110

Lateral line scales ae a ? 115 T14-120 164-177

Depth in standard length be ae 2°4. 2 2:2 DOG)

Gill-rakers in lower arch a ae g-10 12 12 9

Head in standard length fe He 4°5 3°5 3°38 4

Coloration a = a ae plain patterned patterned plain

Fleshy lip on maxilla tip ie J Eypresent present present present

Spinules on scales aie sy . vertical vertical flat flat

Pelvic fin of eyed side twisted to the left yes no no yes

Maximum known total length (mm.) 105 63 270 456

Smallest known total length (mm.) .. 100 48 134 334.

Comparison of the four known species of bothid fishes which lack pectoral fins.

From the table it is clear that the only important character that the two

species of Achiropsetta have in common, and distinct from the two species

placed in the genus Mancopsetta, is the unusual form of the scales with vertically

projecting spinules.

Although A. tricholepis is stated to have a flat scaled interorbital space

(Norman, 1930, 1934), a specimen examined from the collection in the British

Museum (1933.5.8: 1) shows a clear bony ridge. M. maculata on the other hand

was said (Norman, 1934) to have a bony ridge without scales. In the specimen

of M. maculata examined however, scale pockets were clearly present on the

ridge. It seems likely that the scales were rubbed off in the trawl net. A scaled

ridge is therefore present in M. maculata, M. milfordi and A. tricholepis. Nothing

is known concerning this feature in A. slavae.

A NEW SPECIES OF FLATFISH, MANCOPSETTA MILFORDI 185

Another difference, the thickened trunk in Achiropsetta, is most probably

a function of size as it is present in Achiropsetta (of which only small specimens

are known) and the smaller of the two M. milfordi but not in the larger nor in

M. maculata.

From the illustrations in Norman (1934) there is a strong suggestion of

marked differences in the shape of the head in M. maculata and A. tricholepis

but this is caused by illustrating the largest available example of the former

species and the smallest of the latter. Figure 2 gives some idea of the changes of

head shape that may occur in a species with an increase in size.

€ << i

2 at

po)

Ficure 2. Head shapes of various specimens of the genus Mancopsetta redrawn from various

sources (not to scale).

A. M. maculata of 238 mm. total length (After Norman, 1934).

B. M. maculata of 134 mm. total length (After Gunther, 1880).

C. M. milfordi of 334. mm. total length.

D. M. slavae of 63 mm. total length (After Andriashev, 1960).

M. slavae of 56 mm. total length (After Andriashev, 1960).

M. tricholepis of 100 mm. total length (After Norman, 1930).

186 ANNALS OF THE SOUTH AFRICAN MUSEUM

From the above it is evident that there is only one important and constant

difference between the two genera Mancopsetta and Achiropsetta, viz. the type

of spinules present on the scales. At the same time, however, there are several

clear points of similarity between A. tricholepis and M. milford: and again

between A. slavae and M. maculata.

It is extremely probable that the presence of vertically projecting spines

in Achiropsetta is a larval or juvenile character as similar spines occur in many

bothid larvae (Kyle, 1913). Andriashev (1960) holds a similar view and has

stated ‘It is very probable that the peculiar prickliness of the body of Achiropsetta

(that is, the strongly developed, vertically projecting spines) can be considered

as a larval character of a caenogenetic nature’. He also noted the similarity in

fin counts between A. slavae and M. maculata, as well as the fact that these two

species had the most similar distribution. He concluded, however, that the

specimens of A. slavae could not be assigned to the genus Mancopsetia since in the

latter genus the body is not transparent and the scales do not have the vertically

projecting spinules. Andriashev further states that it is not possible to explain

these in terms of development, as the difference in size between the smallest

M. maculata and the largest A. tricholepis is only 29 mm. The greatest similarities

are, however, between M. milfordi and A. tricholepis, where the minimum

difference between the two species is 229 mm., and between A. slavae and

M. maculata, where the difference is 71 mm.

While it is not possible at this stage in our knowledge of these fishes to

suggest that A. tricholepis is actually the juvenile stage of M. milfordi or A. slavae

that of M. maculata, it is suggested that for the reasons given above, and bearing

in mind that these four species, in lacking pectoral fins, form a unique group

within the family Bothidae, the species should not be separated into two genera

but should rather be united into one genus, Mancopsetta. The differences

between the species of the former genus Achiropsetta and those of Mancopsetta

being far more likely due to growth rather than major genetic differences.

The generic definition of Mancopsetta will, however, have to be modified from

that given by Norman (1934), not only to include the species formerly placed

in the genus Achiropsetta, but also the new species M. milfordi.

Genus MANCOPSETTA

Lepidopsetta (non Gill, 1864) Gunther, 1880, p. 18.

Mancopsetta Gill, 1881. p. 373.

Achiropsetta Norman, 1930. p. 361.

Body fairly elongate, compressed and sinistral. Eyes large, close together

and with the upper parts of each eyeball densely scaled. Lower eye a little in

advance of the upper. Mouth of moderate size not reaching farther back

than a point level with the posterior edge of the lower eye, maxillary narrow,

not expanded behind. Jaws and teeth about equally developed on both sides.

A small fleshy growth over the front tip of maxilla. Teeth small, conical and

usually uniserial; vomer toothless. Few gill-rakers, those present being short.

A NEW SPECIES OF FLATFISH, MANCOPSETTA MILFORDI 187

Dorsal fin starting far forward on head. All fin rays simple, scaled. Pelvic fin

of eyed side may or may not be posteriorly deflected to the left. No true pectoral

fins but a fin bud may be present in small specimens. Lateral line on both sides

single, straight and well developed.

Type species Lepidopsetta maculata Gunther, 1880.

The genus contains four species:

M. maculata (Gunther) 1880.

M. tricholepis (Norman) 1930.

M. slavae (Andriashev) 1960.

M. milfordi sp. n.

DIsTRIBUTION

Andriashev (1955) has discussed the distribution of these fishes and has

shown that they are known from a few specimens found over a wide area of

the Southern ocean. The following are the only published locality records:

M. maculata. This species is known from three specimens, all caught by

bottom trawling in deep water—

Marion Island: 46° 43’ S. 38° 5’ E. 580 m. (Gunther, 1880).

Falkland Islands: 45° 45’ S. 59° 35’ W. 311-247 m. (Norman, 1937).

South Georgia: 53° 48’ S. 35° 57’ W. 411-401 m. (Norman, 1938).

M. tricholepis. This species is known from only two examples taken by

bottom trawling in shallow water —

Tierra del Fuego: 53° 00’ S. 68° 06’ W. 22-20 m. (Norman, 1930).

Falkland Islands: (No details available) (Norman, 1937).

M. slavae. Four specimens of this species are known and all were caught in

midwater using an Isaacs—Kidd midwater trawl—

Wilkes Land: 64° 51’ S. 114° 17’ E. 725 m. cable (Andriashev, 1960).

(Antarctic) 63° 50’ S. 116° 25’ E. 1,100 m. cable (Andriashev, 1960).

64° 22’ S. 121° 08’ E. 1,100 m. cable (Andriashev, 1960).

64° 10’ S. 127° 46’ E. 1,100 m. cable (Andriashev, 1960).

M. milfordi. Known from only two specimens both taken by bottom trawl

in deep water—

Cape of Good Hope, west of Cape Town. 550 m.

Cape of Good Hope: 33° 40’ S. 17° 30’ E. 675 m.

Some of these records are very widespread, especially M. maculata and

suggest that these fishes are more common than the small number of known

records would suggest. This is undoubtedly due to the very small amount of

trawling that has been undertaken in the Southern ocean. More collecting would

be very useful, as a good set of growth stages would certainly show whether

M. slavae and M. maculata are in fact growth stages of the same species, and

likewise with M. milfordi and M. tricholepis.

188 ANNALS OF THE SOUTH AFRICAN MUSEUM

ACKNOWLEDGEMENTS

I am grateful to Professor J. L. B. Smith of Grahamstown, Dr. A. P.

Andriashev of Leningrad, and Mr. P. R. Sloan of La Jolla for help in obtaining

literature; to the Trustees of the British Museum (Natural History) for the

loan of valuable material for comparative purposes; to Messrs. Irvin and

Johnson (Pty.) Ltd. for presenting these two interesting specimens to the

South African Museum; and to Dr. F. H. Talbot and my wife, Mary-Louise

Penrith, for reading the manuscript.

The Trustees of the South African Museum are grateful to the Council

for Scientific and Industrial Research for the award of a grant to publish this

paper.

SUMMARY

A new species of bothid, Mancopsetta milfordi (Pisces: Bothidae), is described

from deep water off the Cape of Good Hope. Four species of bothids are known

which lack pectoral fins. They have been placed in two genera, Mancopsetia

and Achiropsetta. It is shown that the two genera exhibit a marked overlap in

characters and can be divided on only one character, which is probably a

juvenile feature. The genus Mancopsetta is redefined to include all four species.

REFERENCES

ANDRIASHEV, A. P. 1960. Families of fishes new to the Antarctic. 3. Pelagic young of flatfish

(Pisces, Bothidae) off the Antarctic coast. Zool. Zh. 39: 1056-1061.

Git, T. 1881. Account of recent progress in Zoology. Rep. Smithson. Instu, 1880: 331-390.

GunTHER, A. 1880. Report on the shore fishes. Ref. Voy. Challenger 1873-6 1(6): 1-82.

Kyte, H. M. 1913. Flatfishes (Heterosomata). Rep. Danish oceanogr. Exp. medit. 1908-10 2 (At).

Norman, J. R. 1930. Oceanic fishes and flatfishes collected in 1925-27. Discovery Rep. 2: 263-370.

Norman, J. R. 1934. A Systematic monograph of the flatfishes Heterosomata I. London, British Museum

(Nat. Hist.).

Norman, J. R. 1937. The coast fishes II. The Patagonian region. Discovery Rep. 16: 3-150.

Norman, J. R. 1938. The coast fishes III. The Antarctic zone. Discovery Rep. 18: 3-104.

Plate III

Ill

Ann. S. Afr. Mus., Vol. XLV

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Suiru, A. B. 1956. New Plonia species from South Africa. Ann. Mag. nat. Hist. (12) 9: 937-945.

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SmirH, C. D. 1954. South African Plonias. In Brown, X. Y. Marine faunas. 2nd ed. 3: 63-95.

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SYNONYMY

Arranged according to chronology of names. Published scientific names by which a species

has been previously designated (subsequent to 1758) are listed in chronological order, with

abbreviated bibliographic references to descriptions or citations following in chronological

order after each name. Full references must be given at the end of the paper. Articles and

recommendations of the International code of zoological nomenclature adopted by the XV International

congress of zoology, London, July 1958, are to be observed (particularly articles 22 and 51).

Examples: Plonia capensis Smith, 1954: 86, pl. 27, fig. 3. Green, 1955: 23, fig. 2.

When transferred to another genus:

Euplonia capensis (Smith) Brown, 1955: 259.

When misidentified as another species:

Plonia natalensis (non West), Jones, 1956: 18.

When another species has been called by the same name:

[non] Plonia capensis: Jones, 1957: 27 (= natalensis West).