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THE VALIDITY OF RAJA RHIZACANTHUS REGAN

AND RAJA PULLOPUNCTATA SMITH, BASED ON A

STUDY OF THE CLASPER

P. A. HuLLey

South African Museum, Cape Town

(With 8 figures in the text)

CONTENTS

PAGE

Introduction SD Rea ace at DRM aD a oiAue AO

The Claspers of Myxopterygia . : -. 4098

Clasper of R. rhizacanthus

(i) the external anatomy . : - 499

(ii) the internalanatomy . . . 500

Clasper of R. pullopunctata

(i) the external anatomy . : - 505

(ii) the internal anatomy . . . 505

Discussion . ; F P : ; . 508

Acknowledgements. : Sect err see ey TS

Summary . : F : : FOS fa TA

IVELETENCES Mitsm me MPR tk tacts Bul ie stint

INTRODUCTION

The present classification of South African skates is more or less tentative,

for this difficult genus shows great variability in its morphological characters,

which vary with age and/or sex in the individuals within the species. This

high intraspecific variability probably accounts for the present inclusion of

95-100 species in the genus Raja. Several South African species have, as yet,

proved to be indistinguishable from European species from the corresponding

latitudinal belt in the northern hemisphere (Bigelow & Schroeder, 1953), and

it would appear that these pairs represent cases of ‘masked bipolarity’ (Ekman,

1953). But in very few cases have actual comparisons of the specimens from

the two regions been made, although Norman (1935) has given some brief

references.

Raa alba, Lacépéde, from the N.E. Atlantic is reported here under the

same name, but it appears to be cosmopolitan in distribution, being recorded

from Morocco (Pietschmann, 1906), West Africa (Fowler, 1936) and Angola

(da Franca, 1959).

497

Ann. S. Afr. Mus. 48 (20), 1966: 497-514, 8 figs.

498 ANNALS OF THE SOUTH AFRICAN MUSEUM

Norman expressed some doubt about the identification of R. batis from

South Africa but the material he examined included a single stuffed specimen,

on which accurate measurements were impossible. This South African species

is now thought to be distinct from R. batis Linnaeus, and Smith (1964), on the

basis of the shape, the presence of a single median spine and the general

markings, has reclassified this skate as R. pullopunctata, although he points out

that only juvenile material was examined.

Raja rhizacanthus Regan, has been thought to be identical with the Euro-

pean thorn-back skate R. clavata Linné, but this has been a matter of speculation.

Barnard (1925) and Fowler (1940) have included R. rhizacanthus as a synonym

of R. clavata, but Norman regarded the two as distinct species on the basis of

spination and the position of the vent. This has been followed by Smith (1961).

It is the purpose of this paper to compare and contrast certain morpho-

logical characters, in the hope that the validity of these latter two South

African species may be determined with greater certainty.

Since skates show such great variations in external features, a more

critical method of examination needs to be employed. Leigh-Sharpe (1920-

1926) has pointed out that in the genus Raja, individual species can be recog-

nized by the morphological structures of their claspers. He has extended this

further and has postulated the existence of pseudogenera (termed Alpha-,

Beta- and Gamma-raia, etc.), recognizable by the similar presence or absence of

the clasper elements. Ishiyama (1958) has shown that in Japanese rajids,

although intraspecific variations in the clasper can be recognized, the ‘external

and internal structures of the clasper are species specific without exception’

(p. 224). On this basis he has also been able to postulate phyletic, generic and

inter-specific relationships, and has concluded that ‘the characters in the male

external organ (claspers) of the Japanese rajids seem to give the most reliable

basis for the systematics of this group of fish’. (p. 243.)

Hence it would appear that since the anatomy of the clasper is valid for

the purposes of identification, it should also be valid for the purposes of com-

parison of geographically separated species. However, ‘genitalic differences

must be evaluated just like other characters’ (Mayr et al., 1953, p. 109), and so

differences in the external and measurable characters of the specimens must

also be taken into account.

THe CLASPERS OR MyxXOPTERYGIA

Comprehensive anatomical studies have been carried out on the claspers

of European elasmobranchs by Petri (1878), Jungersen (1899) and Huber

(1901). Two points of view were held as to the function of the claspers: that

they were ‘holders’ (analogous to hands) was originally postulated, but they

were later recognized as organs of intromission. Extensive study on the external

anatomy and the function of the clasper in the various elasmobranch groups

has been made by Leigh-Sharpe, and further work on the function of the organ

has been performed by Friedman (1935).

RAJA RHIZACANTHUS REGAN AND RAJA PULLOPUNCTATA SMITH 499

The nomenclature used in this paper is mainly in accordance with that of

Leigh-Sharpe and Ishiyama, together with that of the above-mentioned

authors.

THE CLASPER OF R. RAIZACANTHUS REGAN

The claspers from seven adult specimens of R. rhizacanthus, trawled off

Cape Columbine and in False Bay, were examined.

apopyle

hypopyle

slit

signal

shield

Sw90-OL

pseudorhipidion

pseudosiphon

sentinel

A f

sentina

| 2:0cms |

spike

Fic. 1. Raja rhizacanthus

A, external view of right clasper from dorsal side; B, lateral view of right clasper, gngacd to

show structural features of glans.

(i) The external anatomy of the clasper (fig. 1 A, B)

The clasper of R. rhizacanthus is a moderately long, strongly built structure,

the outer surface of which is entirely naked. Proximally the clasper is cylin-

drical, but from about 1/3 its length from the distal end, it becomes broader

and dorso-ventrally flattened, especially on its ventral surface. It tapers

gradually towards its distal end and terminates in a broadly rounded, spatulate

500 ANNALS OF THE SOUTH AFRICAN MUSEUM

tip. The ventral surface is pale and the dorsal surface tones with the general

coloration of the body.

The apopyle (fig. 1 A) is situated dorsally, some little distance behind the

vent, and the appendix groove, arising from this point, runs across to the outer

margin of the organ, and continues along the distal two-thirds of the lateral

edge almost to the tip of the clasper. In some cases, due to the skin stretching

across the dorsal terminal 1 cartilage, the groove may be seen from the dorsal

side. Proximally the groove is bordered on by the two ‘scroll-like’ dorsal and

ventral marginal cartilages, so that the edges of the groove closely approximate

to form a tube, running from the apopyle to the hypopyle. Distally, from about

half the clasper length, fleshy lips border the groove, and during erection,

brought about by the powerful adductor muscles, and by vascular dilation

(Friedman), these lips are opened and the structures of the clasper glans

protrude (fig. 1 B).

Two pouches are present on the dorsal surface of the concavity of the

clasper glans (fig. 1 B), the smaller, more proximal slit and the larger, distal

pseudosiphon. The median hypopyle is bordered dorsally by the pseudo-

rhipidion, a plate-like structure employed as a splash-plate for ejaculating

spermatozoa and distinguished from the rhipidion of Leigh-Sharpe in not

being fan-shaped or pitted. Posterior to the hypopyle, and at about the same

level as the pseudorhipidion, is a fleshy pad, the szgnal, which is capable of

rotation about the longitudinal axis of the clasper. The sentinel is strongly

developed and in older specimens its knife-like edge is exposed. There is a deep

sentina situated distally, its inner border raised into a curved spike. The ventral

shield is narrow and not well developed. The lining of the concavity is naked,

scale and spine being absent.

All these above-mentioned structures are associated with the cartilages

of the terminal group.

(ii) Lhe internal anatomy of the clasper (figs. 2, 3)

The skeleton of the clasper is a continuation, in the median axis, of the

basipterygium of the fin, and is composed of two groups of cartilages, the basal

group (including the basipterygium) and the terminal group.

(a) The basal group (fig. 2)

Ishiyama has pointed out, that in Japanese rajids, the basal group is not

species specific, and, although White (1937) has proved that the number of

proximal segments and other cartilages in the basal group tend to vary in large

groups of the elasmobranchs, the basal group may only be used in phyletic

considerations among the batoid fishes. Examination of the basal group of

R. rhizacanthus seems to support this view, since the same seven cartilages are

present as in the Japanese rajids (see Ishiyama, fig. 7).

The basal group in R. rhizacanthus consists of the basipterygium, and

b, and b, cartilages, the Beta-cartilage, and the axial cartilage, which extends

RAJA RHIZACANTHUS REGAN AND RAJA PULLOPUNCTATA SMITH 5OI

basipterygium

RS WS fin rays

. ‘ \™“

b, cartilage

beta cartilage

dorsal marginal

axial

l 4-0cms

Fic. 2. Raja rhizacanthus. Cartilages of the basal group of the

clasper.

to the terminal part of the clasper, and is covered by the dorsal and ventral

marginal cartilages (fig. 2). The basipterygium is a short, stout structure, to

which are attached in a groove on its lateral margin, the last 6 fin rays of the

pelvic fin. Distally, the basipterygium is elongated on its dorsal surface to

form a protuberance which overlaps the b, cartilage. The proximal end of the

b, cartilage is visible from the dorsal side, but the Beta-cartilage, situated

dorsally to the b, and b, cartilages, completely obscures the b, cartilage and

the distal end of b,. The Beta-cartilage is more or less flat, serving as a region

of attachment for the m. flexor internus, but is slightly thickened and upraised

at its proximal end, forming a shelf.

The distal ends of the b, and Beta-cartilage are superimposed so that both

of these elements play a part in the joint with the axial and marginal cartilages.

The long axial cartilage is cyclindrical at its proximal end, but it becomes

dorso-ventrally flattened distally and assumes a spatulate appearance. It is

tightly enclosed by the calcified dorsal and ventral marginal cartilages and is

only free at its spatulate tip, although it is visible dorsally. The dorsal marginal

cartilage attaches tightly to the axial, starting where the axial is connected to

the b,/Beta joint, and runs along the outer lateral margin of the axial for about

half its length. The dorsal marginal cartilage is somewhat broadly pointed

anteriorly but it becomes expanded distally, its outer lateral edge forming the

dorsal edge of the ‘scrolled’ groove of the clasper. The ventral marginal carti-

lage, unlike the dorsal marginal, starts posteriorly to the axial and is a flat,

tongue-like structure. Its outer lateral margin forms the ventral lip of the

502 ANNALS OF THE SOUTH AFRICAN MUSEUM

‘scroll’ and medially it is attached to the axial, overlying it distally. The ventral

marginal cartilage extends farther down the length of the clasper than the

dorsal marginal cartilage. Attached distally to the axial and to the marginal

cartilages, are the elements which comprise the terminal group of cartilages.

(b) The terminal group

The elements which comprise the terminal group of cartilages are asso-

ciated with the structures of the glans, and may be divided into three types:

ventral terminal, dorsal terminal and accessory cartilages.

1. Ventral terminal (figs. 3 A, B, G)

The ventral terminal cartilage is attached to a groove in the distal end of

the ventral marginal cartilage. It has a J-like shape, being by far the largest

cartilage of the terminal group. It is strongly curved medially, and runs around

the axial cartilage, so that it can be seen from the dorsal side. The upright

portion of the ventral terminal cartilage is fairly well developed and there is a

small shelf on its dorsal side, which is seen as the shield of the clasper glans.

Distally, the ventral terminal is thick and somewhat pointed.

2. Dorsal terminal 1 (figs. 3 C, G)

The dorsal terminal 1 cartilage (‘cover-piece’ of Jungersen) is situated on

the dorsal side of the clasper, partially covering the dorsal terminal 2 cartilage,

to which it is attached along the length of its longest margin. It is flatly rounded

and curved proximally, so that it is elongated on its outer lateral margin. From

this point, there is a shelf, running in a curve along the anterior margin, which

serves as a point of insertion for the aponeurosis of the m. dilatator, which conse-

quently covers the whole area of the cartilage. Distally, the cartilage is flat

and its distal end is attached, together with the dorsal terminal 2 cartilage, to

the axial cartilage. The dorsal terminal 1 cartilage is associated with the

development of the pseudosiphon.

3. Dorsal terminal 2 (figs. 3 D, G)

This curved element is inserted between the dorsal terminal 1 and the

dorsal marginal/axial cartilages. It is firmly attached to the distal region of the

dorsal marginal cartilage, and by means of a ligament (which forms the shelf

between the slit and pseudosiphon) it is attached at its distal end to the outer

lateral margin of the axial cartilage, at about 2/3 the length of that cartilage

from its anterior end. The dorsal terminal 2 cartilage is strongly curved, and

raised along the side of longest curvature, to form a flat surface ‘articulating’

with the dorsal terminal 1 cartilage. The dorsal terminal 2 cartilage is asso-

ciated with the slit.

4. Accessory cartilages 1 and 2 (figs. 3 E, G)

These two cartilages are strongly united and are attached to the distal

end of the ventral marginal cartilage. The accessory cartilage 1 is the S-shaped

RAJA RHIZACANTHUS REGAN AND RAJA PULLOPUNCTATA SMITH 503

axial

dorsal marginal

dorsal terminal 1

dorsal terminal 2

accessory 3

SW 0-01

accessory 1

ventral terminal

accessory 2

| 2:0cms |

Fic. 3. Raja rhizacanthus. Cartilages of the terminal group of the clasper.

A, ventral terminal (ventral view); B, ventral terminal (dorsal view); C, dorsal terminal 1

(dorsal view); D, dorsal terminal 2 (dorsal view); E, accessory cartilages 1 and 2 (dorsal

(view); F, accessory cartilages 3 and 4 (ventral view); G, terminal cartilages in situ from

dorsal side.

element, and its knife-edged protruberance is the sentinel. Accessory cartilage 2

is elongate in the longitudinal axis of the clasper, and its distal end is recurved

and hook-like, forming the spike of the clasper glans.

5. Accessory cartilages 3 and 4 (fig. 3 F, G)

Accessory cartilages 3 and 4 form the signal of the glans and are situated

on the ventral side of the clasper, between the upright portion of the ventral

terminal cartilage and the accessories 1 and 2, The smaller proximal cartilage,

504. ANNALS OF THE SOUTH AFRICAN MUSEUM

accessory 4 is attached in a groove formed between the accessory cartilages

1 and 2 and the ventral marginal cartilage; accessory 3 is movable on accessory 4

and its distal end is bluntly rounded.

Musculature

Only a brief mention of the musculature of R. rhzzacanthus needs be made

for it is identical with that of R. clavata as given by Jungersen.

M. dilatator

Proximally this consists of a single muscle mass, but distally it seems to be

split into dorsal and ventral muscles. Its origin is on the axial, b, and b, carti-

lages, and it inserts as an aponeurosis on the shelf of the dorsal terminal 1

cartilage.

The m. compressor sacct, m. adductor, m. flexor (not extensor as given in Junger-

sen), and muscles of the fin are the same as for R. clavata.

hypopyle

rhipidion

SUD 0-p

pseudosiphon

shield

spike

Fic. 4. Raja pullopunctata

A, external view of right clasper from dorsal side; B, lateral view of right clasper, opened to

: show structural features of the glans.

RAJA RHIZACANTHUS REGAN AND RAJA PULLOPUNCTATA SMITH 505

THE CLASPER OF R. PULLOPUNCTATA SMITH

The claspers from three adult specimens of R. pullopunctata, trawled West

of Cape Town and in Algoa Bay were examined.

(i) The external anatomy of the clasper (fig. 4 A, B)

The clasper of R. pullopunctata is long and stout; its cyclindrical body is

dorso-ventrally flattened distally, and slightly truncate, giving a spatulate

appearance. The glans is much broader than the rest of the clasper, due to the

strong development of the shield, which can be clearly seen from the dorsal

side. The claspers are entirely naked, scale and spine being absent. The apopyle

(fig. 4 A) opens some distance away from the vent, on the dorsal side.

The rhipidion (fig. 4 B) is well developed and fan-shaped and it is attached

along the inner ventral wall of the clasper, from the region of the hypopyle to

about half-way along the length of the glans. Its lower surface is pitted with

cavities of irregular outline, and this spongy tissue is said by Leigh-Sharpe to

be erectile and to act as a splash-plate for the ejaculating spermatozoa.

R. pullopunctata may be placed in the pseudogenus Gamma-raia, for there

is a reduction and crowding of the structural features of the glans. As in all

Gamma-raia, the signal is absent, while the shield is very well developed and

extends along the whole ventral surface of the glans, from the level of the

hypopyle almost to the distal extremity of the clasper. The distal region of the

shield is covered by pleated epithelia, but this is so thin at the outer lateral

edge, that the knife-like appearance of the shield is not unlike the sentinel of

R. rhizacanthus.

Both the slit and the pseudosiphon are present in the dorsal wall of the

concavity of the glans. In R. pullopunctata the pseudosiphon is larger and more

distally placed than the slit, and these two cavities are separated by a prominent

cartilaginous shelf. The pseudosiphon is well separated from the hypopyle by

the elongated dorsal marginal cartilage.

Medially placed is a large, single, tongue-like structure, which examination

of the terminal cartilages reveals as the spike (cf. Leigh-Sharpe). Although

covered by a thick layer of epithelial tissue, the calcified cartilage can be easily

felt. The small accessory 1 cartilage is not greatly developed, and the sentinel

is not a recognizable element in the external appearance of the clasper.

(ii) The internal anatomy of the clasper (fig. 5)

The basipterygium, b, and b, cartilages and the Beta-cartilage are the

same as in R. rhizacanthus. The axial cartilage is long, cyclindrical at its proximal

end, but narrower and dorso-ventrally flattened distally. The distal end of the

axial is more heavily calcified than the proximal region, and is slightly curved

outwards, terminating in a bluntly rounded point. The dorsal marginal carti-

lage starts more proximally than the ventral marginal cartilage, and runs for

about 2/3 the length of the axial, to which it is tightly bonded for its entire

length. The dorsal marginal cartilage is convex at its proximal end, but becomes

506 ANNALS OF THE SOUTH AFRICAN MUSEUM

axial

dorsal marginal

ventral marginal

dorsal terminal 2

ventral terminal

Fic. 5. Raja pullopunctata. Cartilages of the terminal group of the clasper.

A, ventral terminal (dorsal view) ; B, ventral terminal (ventral view) ; C, dorsal terminal 1

(dorsal view); D, dorsal terminal 2 (dorsal view); E, accessory 1 (ventral view); F,

accessory 2 (dorsal view); G, terminal cartilages in situ from dorsal side, but with dorsal

terminal 1 removed.

flatter distally and is extended in a small point, forming the shelf between the

pseudosiphon and the hypopyle. The ventral marginal cartilage is flat and

slightly expanded distally, so that it more or less overlaps the axial cartilage,

to which it is united. Its distal end is truncate.

1. Ventral terminal cartilage (figs. 5 A, B, G)

As in R. rhizacanthus, the ventral terminal is J-shaped, but its distal end is

not so strongly developed. The cartilage is attached to the inner surface of the

‘scroll-like’ ventral marginal cartilage. It is locked to this cartilage by means of

RAJA RHIZACANTHUS REGAN AND RAJA PULLOPUNCTATA SMITH 507

a protuberance, situated ventrally about 1/3 of the length of the ventral

terminal from its proximal end. The protuberance engages with a corre-

sponding point (the minute ‘sentinel’) of the accessory cartilage 1, hooking

the two elements together. The ventral terminal cartilage does not extend to

the tip of the clasper. The outer lateral edge of this cartilage is well developed

and calcified, forming a convex lamina, the shield of the clasper glans. Distally,

the apex of the ventral terminal is grooved, through which the distal regions

of the axial and dorsal terminal 2 cartilages pass, before becoming dorso-

ventrally flattened. The upright limb of the J-like ventral terminal is raised

into a ridge on its dorsal surface.

2. Dorsal terminal 1 (fig. 5 C)

This cartilage is situated on the dorsal surface of the clasper, and is

attached along its outer edge to the dorsal terminal 2 cartilage. The dorsal

terminal 1 cartilage is ‘shield-like’ in appearance and its proximal end is

elongated into an obtuse point, to which the dorsal bundle of the m. dilatator

attaches. The inner distal region of this cartilage is so curved that it wraps

around the axial stem and can be seen on the ventral side, where it slightly

overlaps the upright limb of the ventral terminal cartilage. Distally, the dorsal

terminal I is attached by connective tissue to the axial, dorsal terminal 2 and

accessory cartilages.

3. Dorsal terminal 2 (fig. 5 D)

The dorsal terminal 2 cartilage is attached to the inner distal end of the

dorsal marginal cartilage, so that the point and connective tissue, which forms the

shelf between the pseudosiphon and hypopyle, lie behind the dorsal terminal 1.

The dorsal terminal 2 cartilage is a long, thin, single cartilaginous element,

curving and then re-curving, so that its pointed distal end is attached to the

axial cartilage (fig. 5 G). Proximally, the dorsal terminal 2 is strongly calcified

and has a short blunt protuberance on its outer lateral margin, while distally

calcification is not so marked, the soft cartilage becoming dorso-ventrally

flattened. About half-way along its length, on the inner edge, there is a liga-

ment (forming the shelf between the pseudosiphon and the slit), which arches

and inserts on the axial cartilage about 1/5 the length of this cartilage from

its distal end (fig. 5 G).

4. Accessory cartilage 1 (fig. 5 E)

This minute V-shaped cartilage is attached to the distal end of the ventral

marginal cartilage. The longer of its two arms runs forward along the outer

lateral edge of the ventral marginal, while the shorter traverses the distal end

of the ventral marginal cartilage. The base of the V is slightly pointed (the

minute ‘sentinel’) and is curved inwards, forming the point on which the

ventral terminal engages. It must be noted that this cartilage does not manifest

itself as an external structural element in the glans.

508 ANNALS OF THE SOUTH AFRICAN MUSEUM

5. Accessory cartilage 2 (fig. 5 F)

The accessory cartilage 2 resembles an inverted Y. Its cyclindrical proxi-

mal end is attached to the inner distal end of the ventral marginal cartilage.

The longer limb of the accessory is tightly bonded to the axial, so that distally

these two cartilages resemble a single element. The shorter arm of the cartilage

is simple in shape and projects laterally outwards. Its terminal end is slightly

upturned and forms the spike of the clasper glans.

Musculature

The musculature of R. pullopunctata was found to be identical with the

description of the musculature of R. clavata given by Jungersen, and like

R. batis, the m. dilatator is in two bundles.

(a) Dorsal m. dilatator

This muscle has its origin on the proximal region of the axial cartilage

and its insertion on the dorsal and lateral regions of the dorsal terminal 1

cartilage. The muscle is not strictly dorsal in position but more medio-dorsal,

and is much larger than the ventral m. dilatator.

(b) Ventral m. dilatator

The muscle is entirely separate from its dorsal counterpart and has its

origin on the ventral proximal region of the axial cartilage and the distal end

of the b, cartilage. It inserts as connective tissue across the surface of the ventral

terminal cartilage, although some fibres attach to the tip of the axial cartilage.

The m. compressor sacci, m. adductor, m. flexer and the muscles of the fin are

the same as for R. clavata.

DIscussION

Two pairs of claspers from specimens of R. batts Linnaeus, caught $.W.

of Ireland, and a pair of claspers from R. clavata Linnaeus, caught at Lowestoft,

were examined for purposes of comparison.

Although there is a marked difference in the size of the claspers of R.

pullopunctata and R. batis, the general external appearance of the claspers is

similar. In both, the clasper is long, stout and naked, becoming dorso-ventrally

flattened and spatulate at its terminal end. The outer lateral edge of the shield

can be seen from the dorsal side in both species, but in R. batis it is more promi-

nent. This may be due to differences in the size of the claspers. However,

examination of the clasper glans reveals that the structural features in R.

pullopunctata and R. batis are different (figs. 4 B, 6).

The pseudosiphon and slit are present on the inner dorsal surface of the

glans in both species, but their formation is somewhat different, although they

are associated with the degree of development of the dorsal terminal cartilages

in both cases. In R. pullopunctata there is a marked shelf-like ridge separating

RAJA RHIZACANTHUS REGAN AND RAJA PULLOPUNCTATA SMITH 509

shield

slit

hypopyle

rhipidion

sentinel

we “™ spike

pseudesiphon

| 4-0cms |

Fic. 6. Raja batis. Lateral view of right clasper, opened to show

structural features of the glans.

the pseudosiphon from the slit; this shelf is found to be wanting in R. batis.

The pseudosiphon is similarly situated in the two species, but in R. pullopunctata

the pseudosiphon resembles a concavity rather than the simple pouch found in

R. batis. The slit is more proximally situated in R. pullopunctata, occurring about

half-way along the length of the glans (about one-third the length in R. batis).

The hypopyle seems to be more distally placed in R. batis, but this may be due

to the heavier development of the shield. The rhipidion is pitted and fan-

shaped in both species, occurring along the inner ventral wall of the hypopyle,

and extending about half-way along the length of the glans in R. pullopunctata

and about two-thirds the length in R. batis. The rhipidion is more compact in

R. batis. The prominent shield extends along the whole inner ventral surface of

the glans in both species, but it is thinner and covered with pleated epithelia

510 ANNALS OF THE SOUTH AFRICAN MUSEUM

along its entire length in R. batts, while in R. pullopunctata the broader shield

is only pleated at its distal region.

The most noticeable difference in the structure of the claspers is in the

presence of the enlarged sentinel in R. bates, which extends distally and fits

together with the spike. In R. pullopunctata, the sentinel is reduced and lies under

the rhipidion, so that it is not seen when the glans is opened, and these two

elements are not expanded terminally as they are in R. batis.

As has been pointed out, the visible external characters of the clasper are

dorsal terminal 2

axial

dorsal terminal 3

Fic. 7. Raya batis. Cartilages of the terminal group.

A, dorsal terminal 1 (dorsal view); B, ventral terminal (dorsal view) ; C, accessory 1

(dorsal view); D, accessory 2 (dorsal view); E, dorsal terminal 2 and 3 in position.

RAJA RHIZACANTHUS REGAN AND RAJA PULLOPUNCTATA SMITH bel

closely associated with the structure and number of the internal cartilages,

and therefore differences in the structure of the glans will be shown by differ-

ences in the terminal cartilages. In R. pullopunctata there are a total of five

cartilages in the terminal group (2 dorsal terminals, 1 ventral terminal and

2 accessory terminals), while in R. bats six terminal cartilages are present (3

dorsal terminals, 1 ventral terminal and 2 accessory terminals) (figs. 5, 7).

Although there is a great difference in the size of these elements, their

differences in shape and their position may be examined. The dorsal terminal 1

cartilage is similarly situated in both R. batis and R. pullopunctata, occurring on

the dorsal side of the clasper, and it is flat and plate-like, being slightly convex

distally. In both species, the median edge is bent in such a manner, that the

cartilage wraps round the axial stem and may be seen on the ventral side.

Distally, the cartilage is pointed in the two species, but in R. pullopunctata, the

proximal edge is elongated into a point for the attachment of the aponeurosis

of the m. dilatator, while in R. batis (fig. 7), the proximal edge is almost straight

and somewhat more convex. The dorsal terminal 2 cartilage is attached to the

distal end of the dorsal marginal cartilage in both species, and it is interesting

to note that in R. pullopunctata, the dorsal terminal 2 extends to the tip of the

axial cartilage, while in R. batis, the crescent-shaped dorsal terminal 2 (fig.

7 D, E) is attached to about half way along the axial and that the dorsal

terminal 3 extends to the tip of the clasper, i.e. these two cartilages in R. batis

have been reduced to a single cartilage in R. pullopunctata, although there is

linking between the dorsal terminal 2 and the axial in both cases. The terminal

end of the axial cartilage is similarly curved (laterally outwards) in the two

species, and the attachment of the dorsal terminal 2 of R. pullopunctata and the

dorsal terminal 3 of R. batis (fig. 7 E) is similar.

Although both R. pullopunctata and R. batis possess two accessory cartilages,

the accessory cartilage 1 (forming the sentinel) is reduced to a small point in

R. pullopunctata. In R. batis this cartilage (fig. 7 C) is well developed and extends

down towards the spike, and fits closely to it. The ventral terminal cartilages

are similarly situated in both R. batis and R. pullopunctata and these elements

are similar in shape. Both possess the ‘hooking’ protuberance on the inner

ventral margin, the enlarged convex outer lateral edge and the raised dorsal

ridge. However in R. bats (fig. 7 B) the distal end of the convex edge projects

slightly from the main body of the limb, and the distal end of the ventral

terminal is not so markedly grooved as in R. pullopunctata.

It may therefore be concluded that, in the structure of the glans and in

the number and arrangement of the internal cartilaginous elements, the

claspers of R. pullopunctata and R. batis are different.

Besides differences noted in the structure of the claspers of the two species,

some differences can also be seen in the external characters. Smith (1964)

points out that there is a difference in shape between the two, but examination

of later and adult stages of R. pullopunctata reveals that the shape of the disc

varies and that the pectorals and anterior margins of the disc become more

512 ANNALS OF THE SOUTH AFRICAN MUSEUM

concave, as they do in R. batis. The author is unable to detect any appreciable

difference in shape.

Examination of specimens of comparable size indicates that the inter-

orbital is narrower in R. pullopunctata than in R. batis, and that there is little

difference in the comparative size of the eye.

The most noticeable difference is the presence of the large, single, median,

nuchal spine in R. pullopunctata, which is found both in juveniles and adults

(although sometimes worn down). Except about the eyes, the upper surface of

the disc is entirely devoid of other large spines, as it is in R. batts.

Therefore Smith’s proposal that R. pullopunctata and R. batis are distinct

species as based on the general external morphology, is confirmed on the basis

of the clasper structure. Recently, two large ‘black-bellied’ skates, lacking

signs of a median nuchal spine, were obtained in trawls off Cape Columbine

in 250 fathoms. The external characters of the clasper of the mature male were

seen to be identical with those of R. batis from European waters. Therefore

R. batis Linnaeus also may occur off South Africa; however, further investi-

gation on these specimens is necessary.

It is interesting to note that a ‘black-bellied’ skate from the Falkland

Islands, R. flavirostris Philippi 1892, greatly resembles the South African

R. pullopunctata in possessing a single, large, median, nuchal spine. But as yet,

clasper material is unavailable for the purposes of comparison.

The author was unable to find a single difference, both in the external

structure of the glans and in the number and arrangement of the internal

cartilaginous elements, between the claspers of R. clavata and R. rhizacanthus.

The claspers in these two species are identical.

Although Norman points out that the South African species is closely

related to the European species, he considers that the two are distinct on the

basis of the degree of spination in adults, the position of the vent and the shape

of the snout. Preliminary examination of some two hundred specimens of

R. rhizacanthus has shown that the shape of the snout varies considerably in

local populations, as does the degree of spination, and the position of the vent.

Therefore bearing this in mind, and in view of the fact that the claspers

are identical, the author agrees with Barnard and Fowler that R. rhizacanthus

specimens should be referred to R. clavata and that R. rhizacanthus therefore

becomes a synonym of R. clavata. This is further supported by the fact that

masked bipolarity is already acknowledged in R. alba, so that it is not unlikely

that distribution of this type also occurs in R. clavata.

It may be seen from fig. 8 that the distribution of R. clavata ranges from

Arctic waters to the tropical waters of the Indian Ocean, having been recorded

from greater extremes than R. alba. However, through most of their recorded

range both species occur in the same waters. As yet, these two species have never

been recorded from the equatorial waters of West Africa, but equatorial

submergence probably occurs, allowing gene flow from northern hemisphere

to southern hemisphere and vice versa.

RAJA RHIZACANTHUS REGAN AND RAJA PULLOPUNCTATA SMITH 513

CL aw

ay N

A- @

A:.-

@R. alba ge

AR. clavata @t

Fic. 8. Map showing the masked bipolar distribution of R. alba and R. clavata.

ACKNOWLEDGEMENTS

I am grateful to Messrs. M. J. Holden and C. H. Humphries of the

Fisheries Laboratory at Lowestoft for the R. clavata and R. batis material and

to Mr. S. X. Kannemeyer for assistance in collection of the South African

skates. My thanks are due to Dr. N. F. Paterson for checking the manuscript

and for many helpful recommendations.

The Trustees of the South African Museum acknowledge gratefully the

receipt of a grant from the Council for Scientific and Industrial Research

towards the cost of publication.

514 ANNALS OF THE SOUTH AFRICAN MUSEUM

SUMMARY

After detailed studies of the anatomy of the claspers of the males, it is

considered that Raja rhizacanthus Regan is synonymous with R. clavata Linnaeus

and that R. pullopunctata Smith is distinct from R. batis Linnaeus, but that

R. batis Linnaeus may also occur in South African waters.

REFERENCES

BARNARD, K. H. 1925. A monograph of the marine fishes of South Africa. Ann. S. Afr. Mus. 21:

1-418. .

BiceLow, H. B. & SCHROEDER, W. C. 1953. Fishes of the western North Atlantic. Pt. II. Saw-

fishes, guitarfishes, .. . Mem. Sears Fdn mar. Res. t (2): 1-588.

ExMAN, S. 1953. <oogeography of the sea. London: Sidgwick & Jackson.

Fow ter, H. W. 1936. Marine fishes of West Africa based on the collection of the American

Congo Exped. 1909-15. Bull. Am. Mus. nat. Hist. 70: 1-1493.

Fowter, H. W. 1940. Fishes of the Philippine Islands and adjacent seas. Bull. U.S. natn. Mus.

100: 1-879.

Franca, P. pa. 1959. Subsidio para um catalogo dos nomes vernaculos dos peixes marinhos de

Angola. Notas mimeogr. Cent. Biol. pisc. 5: 1-37.

FriepMAN, M. H. F. 1935. The function of the claspers and clasper glands in the skate. 7. biol. Bd.

Can. 1: 261-268.

Huser, O. 1901. Die Kopulationsgleider der Selachier. Z. wiss. Zool. 70: 592-674.

IsHtyAMA, R. 1958. Studies on the rajid fishes (Rajidae) found in the waters around Japan.

J. Shimonoseki Coll. Fish. 7: 193-394.

Juncersen, H. F. E. 1899. On the Appendices genitales in the Greenland shark Somniosus

microcephalus and other selachians. Dan. Ingolf-Exped. 2 (2): 1-88.

LEIGH-SHARPE, W. H. 1920. The comparative morphology of the secondary sexual characters

of elasmobranch fishes. Mem. I. The claspers, clasper siphons and clasper glands. 7.

Morph. 34: 254-265.

LEIGH-SHARPE, W. H. 1921. The comparative morphology of the secondary sexual characters

of elasmobranch fishes. Mem. II. 7. Morph. 35: 263-358.

LEIGH-SHARPE, W. H. 1922. The comparative morphology of the secondary sexual characters

of elasmobranch fishes. Mems. III, IV, V. 7. Morph. 36: 191-244.

LEIGH-SHARPE, W. H. 1924. The comparative morphology of the secondary sexual characters

of elasmobranch fishes. Mems. VI, VII. 7. Morph. 39: 553-577.

LEIGH-SHARPE, W. H. 1926. The comparative morphology of the secondary sexual characters

of elasmobranch fishes. Mems. VIII, IX, X, XI. 7. Morph. 42: 307-368.

Mayr, E., Linstey, E. G. & Usincer, R. L. 1953. Methods and principles of systematic zoology.

New York: McGraw-Hill.

Norman, J. R. 1935. Coast fishes Pt. I. The South Atlantic. ‘Discovery’ Rep. 12: 3-58.

PIETSCHMANN, V. 1906. Ichthyol. ergebnisse einer reise nach Island. Annln. naturh. Mus. Wien.

21: 72-148.

Perri, K. R. 1878. Die Copulations-organe der Plagiostomen. Z. wiss. Zool. 30: 288-335.

SmitH, J. L. B. 1961. The sea fishes of southern Africa. Cape Town: C.N.A.

SmirH, J. L. B. 1964. Fishes collected by Dr. Th. Mortenson off the coast of South Africa in

1929, with an account of the genus Cruriraja in South Africa. Vidensk. Meddr dansk naturh.

Foren. 126: 283-300.

Waite, E. G. 1937. Interrelationships of the elasmobranchs with a key to the order Galea.

Bull. Am. Mus. nat. Hist. 74: 87-117.

INSTRUCTIONS TO AUTHORS

MANUSCRIPTS

In duplicate (one set of illustrations), type-written, double spaced with good margins,

including TaBLe oF CoNTENTs and SumMAry. Position of text-figures and tables must be

indicated.

ILLUSTRATIONS

So proportioned that when reduced they will occupy not more than 42 in. = 7 in. (7% in.

including the caption). A scale (metric) must appear with all photographs.

REFERENCES

Authors’ names and dates of publication given in text; full references at end of paper in

alphabetical order of authors’ names (Harvard system). References at end of paper must be

given in this order:

Name of author, in capitals, followed by initials; names of joint authors connected by &,

not ‘and’. Year of publication; several papers by the same author in one year designated by

suffixes a, b, etc. Full title of paper; initial capital letters only for first word and for proper

names (except in German). Title of journal, abbreviated according to World list of scientific

periodicals and underlined (italics). Series number, if any, in parenthesis, e.g. (3), (n.s.), (B.).

Volume number in arabic numerals (without prefix ‘vol.’), with wavy underlining (bold type).

Part number, only if separate parts of one volume are independently numbered. Page numbers,

first and last, preceded by a colon (without prefix ‘p’). Thus:

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

When reference is made to a separate book, give in this order: Author’s name; his initials;

date of publication; title, underlined; edition, if any; volume number, if any, in arabic numerals,

with wavy underlining; place of publication; name of publisher. Thus:

Brown, X. Y. 1953. Marine faunas. and ed. 2. London: Green.

When reference is made to a paper forming a distinct part of another book, give: Name of

author of paper, his initials; date of publication; title of paper; ‘In’, underlined; name of

author of book; his initials; title of book, underlined; edition, if any; volume number, if any,

in arabic numerals, with wavy underlining; pagination of paper; place of publication; name

of publisher. Thus:

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

London: Green.

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).