Zoo1.J. Linn. Soc., 48,pp. 305-331. With 2 plates and 21 figures
Augur# 1969
The molluscan genus Gyraulus (Gastropoda : Planorbidae) in
southern Africa
D. S. BROWN*
AND
J. A. VAN EEDENI
Institute for Zoological Research, University of Potchefstroom, T r a m a a l , Republic of
South Afiica
Accepted for publication February 1969
Descriptions are given of the shells and some anatomical features of the freshwater planorbid
snails Gyroulus costulatus costulatus (Krauss) and Gyradus connollyi sp. nov. Topotypes of
costulatus have been examined and are separable from connoUyi only by conchologicalcharacters.
Distribution patterns for the two species established by examination of about 15,OOO snails
from 1188 localitiessuggestthat coshJatus is amember of the tropical fauna, whereas connollyi is
apparently endemic to the temperate climatic region of South Africa. The influence of temperature seems to be important in determining the ranges of these species. The apparent absence of
connollyi from the Rhodesian highlands could be due to a barrier to northwards dispersal
provided by the hot and dry Limpopo river valley.
CONTENTS
.
Introduction
Material and methods
.
Taxonomic background
.
Gyraulus costulatus coshrlatus (Krauss) .
Original description
.
Description of topotypes .
.
Shells from other localities
.
Anatomy
.
Material examined .
Distribution .
Gyraulus connoUyi sp. nov. .
Types and type locality .
Shell
Dimensions .
.
Diagnosis
.
Shells from other localities
.
Anatomy
.
Comparison with Gyraulus costulatus
Comparison with other African Cyrnulus
Material examined .
Distribution .
Derivation .
.
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PAGE
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External Scientific Staff, British Medical Research Council. Present address : c / o Experimental
Taxonomy Section, Zoology Department, British Museum (Natural History), London, S.W.7.
1 Potchefstroom Division of the Bilharzia Research Group of the South African Council for Scientific
and Industrial Research.
19
306
D. S. BROWN AND J. A. VAN EEDEN
Distribution and ecology
Discussion
summary.
.
Acknowledgements .
References
Keytofigurelettering
Appendix.
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INTRODUCTION
The Planorbidae living in the Ethiopian region may be divided into two groups, the
one including forms exceeding 1 cm when full grown (genus Biomphalaria Preston),
and the other composed of forms that rarely approach such a size. The small planorbids
belong either to the Segmentina tribe of Hubendick (1955), or have been classified in
Studer or GyrauZus Charpentier, which are discussed in
the Holarctic genera A&
the section entitled Taxonomic Background.
The number of nominal species of Gyraulus recorded from the Ethiopian region
that should be classified with Holarctic forms, according to conchological and also
anatomical characters, is uncertain and probably does not exceed 20. G. costuIatuF
(Krauss, 1848) is widely distributed and has been frequently recorded, though the
remainder apparently have small ranges. To the south of latitude 18"S, the zone of
the Zambesi and Cubango river systems, there have been recorded only the species
costulatus and lamyi Germain (1905), by Connolly (1939) and subsequent authors.
Identifications of lamy' are regarded as incorrect in the present paper. From observations made in Natal Province, Republic of South Africa, Brown (1967) concluded
that 'G.lamyi'was adapted to temperate climatic conditions, because it had been found
in a higher altitudinal zone than G. costulatus,and was not known to occur in the warm
climatic region near the coast, where G. costulatus is abundant.
The form of GyruuIus costulatus originally described by Krauss has a flattened
whorl with an acute peripheral angulation that may bear a fringe of periostracum
(Plate 1A, B ;Fig. 1M) and it is clearly distinct from the common South African form
of 'G. lamyi',which has a high whorl, an angulation on the underside and a nearly
flat periphery (Plate 2A-E, G, H; Fig. 1 G-L). The latter is similar, as remarked by
Connolly (1939 :490) to a young example of Biompharwiapfkffm'(Krauss). However,
both Gyraulus species are very variable and the present paper describes a study of
morphology and geographical distribution, based on approximately 15,OOO snails
from 1188 localities, the majority situated in the Republic of South Africa.
The anatomy of examples of G?ymulus costulatus from Mozambique, Angola, Leopoldville Congo, and Ethiopia has been described (Azevedo, Medeiros & Da Costa
Faro, 1957; Wright, 1963; Medeiros, 1964; Brown, 1965), but as no information has
been available for South African animals, certain features of snails from near the type
locality in Natal province are now described. The South African form previously
identified as 'G.lamyi' is described as a new species, apparently endemic to the South
African temperate climatic region. Special collections were made in a limited area in
THE MOLLUSCAN GENUS GYRAULUS
307
the eastern Transvaal, in order to determine the distribution of the two species in
relation to the steep climatic gradient produced by the Drakensberg escarpment.
MATERIAL AND METHODS
Approximately 15,000 snails from 1188 localities, obtained by various collectors
between 1953 and 1968 and deposited in the Institute for Zoological Research, University of Potchefstroom. Also, about 1550 snails collected from 100 localities by D. S.
Brown between 1962 and 1965 and deposited in the British Museum (Natural History).
FIGURE
1. Shells in profile (apertural view). Gyraulus costulatus: A-F, Klein Jukskei river,
Johannesburg;M, Umzumbe, Natal. CyrcruZus connoZlyisp. nov.: G-L, Klein Jukskeiriver,
Johannesburg.
As it is difficult to measure small and fragile shells directly, measurements were
taken from drawings made by camera lucida at x12 or x25. Shells were placed in
apertural view with the outer lip just concealing the periphery (Fig. 1). The dissected
snails were preserved in 70% alcohol and had been narcotized with menthol in chloral
hydrate and fixed in hot 4% formaldehyde solution (Van Eeden, 1958).
The underside of the shell referred to in the descriptions is that side towards which
the ultimate whorl is usually deflected, and which shows the greatest area of the aperture
(Plate 1A); the concavity enclosed by the ultimate whorl is the umbilicus. The number
of whorls was counted on the underside, from the embryonic whorl to the lower lip
of the aperture in the manner illustrated by Mandahl-Barth (1958 : Fig. 1).
Accession numbers in the collections of the British Museum (Natural History)
Mollusca Section and the Institute for Zoological Research, University of Potchefstroom are preceded by the initials BMNH or IZP.
308
D. S. BROWN AND J. A. VAN EEDEN
TAXONOMIC BACKGROUND
The genus Gyraulus Charpentier, 1837 (type PZawbis aZbus Muller by designation
Dall, 1870) is a group of small discoidal planorbid species of ‘practically world-wide
distribution’ (F. C. Baker, 1945 :70), having few and rapidly increasing whorls. Baker
(1945,71) believed that Gyraulus should be separated on conchological grounds from
AnisuF Studer (type Helix spirorbis Linn. selected by Gray, 1847), in spite of the
anatomical similarity between these genera. Anisus differs from Gyraulus in having a comparatively large number of whorls, which increase slowly; according to H. B.
Baker (1963), Anisus is not a valid name and should be replaced by Omalodiscus
Benson (1855). Hubendick (1955) accepts that Gyraulus and Anisus are similar in
anatomy and doubts that they should be retained as separate genera ;he placed both in
the Plawbis tribe, in which the stylet is sharply delimited from the soft tissue of the
penis.
Early writers on the African fauna placed small discoidal freshwater shells in
Planorbis, but Pilsbry & Bequaert (1927) classified 24 species from the Ethiopian
region in the subgenus Planorbis (Gyraulus). Connolly (1939) recorded the following
six members of this subgenus from southern Africa.
anderssoni Ancey, 1890. Omambonde ( = Ovambonde), Ovamboland, South West
Africa.
costulatus Krauss, 1848. Umgeni valley, Natal.
crawfmdi Melvill & Ponsonby, 1893. Van Staadens river, South Africa.
lamyi Germain, 1905. Southern Lake Tanganyika.
leucochilus Melvill & Ponsonby, 1903. Killarney lake, Pietermaritzburg, Natal.
natalensis Krauss, 1848. Umgeni valley, Natal.
Some of these species have shells more similar to Ana3u.s than to Gyraulus, and where
the genital anatomy is known this also differs from Gyraulus.
The first reference to the occurrence of Anisus in the Ethiopian region is apparently
by Mandahl-Barth (1954), who placed natalensis Krauss in that genus because of its
slowly increasing whorl. However, the penis of A. nataletlsis becomes gradually more
sclerotized towards the tip (Wright & Brown, 1962), whereas there is a short stylet
with a bulbous base that is sharply delimited from the soft tissue of the penis in Cyraulus
costulatus, and also in Holarctic members of Gyraulus and Anisus. It seems, therefore,
that ‘ A n i d natalensis may represent a distinct group of small planorbids perhaps
peculiar to the Ethiopian region. Another type of penis, in which there is a minute
terminal stylet has been found in a group of species that includes ‘Anisus’coretus De
Blainville (Wright, 1965) and probably also anderssoni Ancey of South West Africa.
Thus, as Connolly (1939) is probably correct in placing crawfordi and Zeucochilus in the
synonymy of nataLmis, there remain costulatus and ‘Zamyi’ to be considered as the
representatives of Gyraulus in southern Africa.
THE MOLLUSCAN GENUS GYRAULUS
309
G. costulatus has a wide range extending from Ethiopia and the Sahara to Cape
Province in South Africa; it is polytypic and subspecies have been described from lakes
in East Africa (Mandahl-Barth, 1954). Only the nominate form is recognized at present
in southern Africa. It appears that no further material of G . lamyi has been recorded
since the original description of two examples apart from the records for South Africa
given by Connolly (1939) and Brown (1967).
Gyraulus costulatus costulatus (Krauss)
Plawbis costulatus Krauss (1848: 83, PI. 5, Fig. 3) Type locality: Umgeni Valley,
Natal.
Plawbis (Gyraulus)costulatus : Pilsbry & Bequaert (1927 : 127);Connolly (1939 : 488).
Cyraulus costulatus costulatus : Mandahl-Barth (1954: 86).
GyauluF costulatus: Brown (1967 : 482).
Original description. Krauss (1848) described a depressed example of this species.
His diagnosis reads : ‘P. testa depressa, pallide cornea, tenui, pellucida, oblique costulatostriata, anfractibus 4 planiusculis, celeriter crescentibus, ultimo carinato, supra
convexiusculo, subtus subplano, 1/3 totius diametri paulum superante ; apertura
periobliqua, transversim oblongosubcordata; peristomate ad marginem superiorem
prominente, arcuato.’
Type in Stuttgart Museum according to Connolly (1939). Diameter2+3lines(5-9mm);
height 0.6 lines (1.3 mm). These dimensions do not correspond to the shell illustrated
by Krauss (reproduced in Plate 1G) which is only about 1.0 mm high at the aperture.
Krauss remarked that the early whorls are almost equally sunken on both sides, and
stated that the periphery of young specimens in which the aperture is somewhat
descending shows a resemblance to Planorbis nitida Muller.
Description of topotypes. It may be presumed that this species was obtained in the
Umgeni river valley near to Port Natal (present day Durban). This area has been
greatly affected by human activities, and the first author was able to obtain specimens
in only two localities; a small stream crossing Quarry Road, Durban (BMNH 1969.23)
and the Mhlangana river at Avoca (BMNH 1969.16). These shells resemble the form
described by Krauss in being depressed with a sharply angular periphery. The majority
including the smallest example of 2.5 mm diameter have a peripheral fringe of periostracum, and the largest example of 5-2 mm diameter completes 3%whorls. However,
none of them is so depressed as the shell illustrated by Krauss, and it appears that
his figure exaggerates the flattening of the whorl. A few of our examples have very
fine and irregular spiral lines on some parts of the shell. Populations resembling
the topotypes were found commonly in the coastal region of Natal (Plate lA, B;
Fig. 1M).
Shells from other localities. In many southern African populations of G . costulatus
it is only the large snails that have the depressed form described by Krauss, and in
other populations even the largest examples may have comparatively high whorls with
a bluntly angular or nearly evenly curved periphery lacking any fringe (Plate lD, F,
J; Fig. 1E,F).Variation in the degree of flattening of the whorl was studied by means of
310
D. S. BROWN A N D J. A. VAN EEDEN
the ratio a/b, where a is the diameter of the shell less the width of the aperture, and b
is the height of the whorl at the mid-point of a (Fig. 16). These dimensionsare preferable
to measurements involving the aperture, as the lip is frequently damaged in these
fragde shells. In each of our samples that includes an adequate size range of individuals,
the small snails have the whorl relatively higher than the large snails (Fig. 1A-F), as
illustrated by the distribution of a/b in relation to a for two population samples (Figs
16 and 17). The increase in a/b may be interpreted as the result of allometric growth
and not as the result of the elimination of less depressed shells by natural selection, as
the small scatter of a/b indicates that small shells are probably never as depressed as
large ones. The greatest value for a/b obtained in our material is 4.1. The shell illustrated
by Krauss (1848) has a value of about 6-0, but it seems that this illustration is inaccurate
for reasons already given. Shells from the region of the type locality have a/b between
2.7 and 3.6 (Fig. 17).
Anatomy. The following description is based on animals from four localities (see
Material examined), including Avoca near the Umgeni river valley, which is the type
locality of Gyraulw costulatus.
The degree of contraction of the animal has an important effect on the appearance
of pigmentation and the following description is of an animal that was narcotized and
killed when the mantle contained air. The sides of the foot and the head are nearly
uniformly grey, the most darkly pigmented part of the body being the tentacle, which
has a dark core extending into the post-tentacular lappet (Fig. 2). The mantle on the
left side (i.e. the side of the genital openings) lacks pigment apart from a few poorly
defined grey blotches. The kidney is outlined by dark pigment and the mantle of the
right side has a few flecks anteriorly and is then more densely pigmented as far back
as the beginning of the digestive gland ;pigment is particularly dense near the columellar
muscle.
The pseudobranch bears a single dorsal lamella (Fig. 2, DL), resembling that
described for Ethiopian animals by Brown (1965 :69, Fig. 30). The only ridge observed
in the pallial region extends for a short distance along the rectum (RR).
The copulatory organ extends posteriorly to the level of the spermatheca, but does
not reach the prostate lobes. External features of the copulatory organ are the penis
sheath (PS) and the preputium (PR), connected by a swollen region (Figs 4 and 7),
which has an internal structure similar to that in the European species G. albus
illustrated by Baker (1945 : P1. 14) and Meier-Brook (1964). Following Baker's terminology, the proximal part of the lumen passes through a papilla (PA), below which is
situated a diaphragm (D). Papilla and diaphragm were visible in an evertedcopulatory
organ (Figs 5 and 6).
The copulatory organ reaches a length of about 1-8mm in large animals (5 mm shell
diameter)". The widest part of the preputium is slightly broader than the penis sheath,
A number of G. cosculam dissected in the course of the present study contained larval trematodes,
and the copulatory organ of some parasitized animalswas smallin comparisonwith apparentlyuninfected
specimens. An unusually small organ was also present in some snails in which no parasites could be
detected by gross dissection. It is evidently necessary to bear in mind that the size of the copulatory organ
may be considerably affected by parasites that may be difficult to detect, or may no longer be present in
the snail.
T H E MOLLUSCAN GENUS GYRAULUS
3
0.5m m
FIGURES
2 to 6. Gyruulus costulutuc. 2, 3, 5 , 6 , from Avoca (near the Umgeni valley), Natal: 2,
anterior part of preserved and relaxed animal viewed from left side with the mantle removed;
3, seminal vesicle and ovotestis; 5 , end-view of everted copulatory organ; 6, lateral view of same
copulatory organ, the outlines of the penis sheath and penis seen through the translucent wall
of the preputium. 4, from North Kaap river, east Transvaal. Junction between penis sheath and
preputium, internal structure seen by transmitted light through whole mount in glycerine.
311
312
D. S. BROWN AND J. A. VAN EEDEN
and the latter (measured to the beginning of the swollen region) is 0-5-1.2 times as
long as the preputium (Figs 7A-D); the range for PS/PR in animals from Avoca was
0.6-1.2. The penis extends nearly the entire length of the penis sheath and the opening
of the vas deferens is subterminal; the stylet which is attached to the tip of the penis
frequently lies within the papilla (Fig. 4). The stylet has a bulbous base and the edges
1 mm
I
FIGURE
7. Copulatory organs from large snails having the shell diameters given in brackets.
A-D, Gyruulus cos&hu: A, Mhlangana river at Avoca, Durban (5.5 mm); B, Umzumbe,
Natal (4-1 mm); C, North Kaap river, East Transvaal(4.6mm); I),Olienhoutspruit,Johannesburg (5.0mm). EH,C.connoflyi sp. nov.: E,Tsolo district, East Cape (4-5 mm);F,Sabie,
East Transvaal (4.3 mm); G, Vereeniging, West Transvaal (4.1 mm); H, Olienhoutspruit,
Johannesburg(5.0 mm).
are rolled over enclosing a channel that opens near the tip, as described by Wright
(1963 :463, Fig. 30).
Up to 11 prostatic lobes of irregular shape and arrangement were observed (Fig. 8) ;
the size and number of lobes were less in animals containing larval trematodes. De
Azevedo et al. (1957) demonstrated by transverse sectioning that the prostatic lobes
open into a duct that is separate from the sperm duct, although closely applied to it;
the two ducts could not be separated by dissection in the present material.
THE MOLLUSCAN GENUS GYRAULUS
313
The spermatheca is commonly elongated and club-like, although sometimes ovoid
or bluntly pointed ; a snail of 4.3 mm diameter was the smallest with orange contents
in the spermatheca (Fig. 9A-M).
At the junction between the male and the female systems there is one pouch (carrefour
of Baker, 1945) between the albumen gland duct and the hermaphrodite duct, and
perhaps another between the sperm duct and the oviduct (Figs 10 and 11). The seminal
ccsfulotus
connollyi
k
4.2
43
46
\'
n .c
\\
4-7
FIGURE
8. Prostatic lobes of Gyruulus costulutus from North Kaap river, East Transvaal and of
G. connollyi sp. nov. from Tsolo district, East Cape. The sperm duct is to the left of the
figure, the vas deferens to the right, and individual shell diameters are given. Although the
sperm duct could not be separated from the prostatic duct to the same extent in different
dissections, the differences are not considered to be significant (see text).
vesicle consists of a thickened region of the hermaphrodite duct, sometimes bearing
blunt projections (Fig. 3). Between 9 and 15 lobes, some arranged in two rows, were
present in the ovotestis in 13 animals from Avoca (Fig. 3).
The radulae were examined of five snails ( 4 . 3 4 9 mm diameter) from Avoca and of
ten snails (4.4-6-0 mm) from the North Kasp river, Eastern Transvaal (Fig. 14). The
central tooth bears two cusps that are symmetrical, or slightly assymmetrical;there are
between 15 and 18 teeth in each half transverse row; a transition may be recognized at
tooth 11 or 12 from the lateral teeth having three major cusps, to the marginal teeth
having comparatively small cusps or none at all. There appear to be no significant
314
D. S. BROWN AND J. A. VAN EEDEN
differences between radulae from the two different localities, though some of the first
lateral teeth of snails from Avoca have one or two interstitial cusps between the ectoand mesocones.
J
FIGUR~
9. Spermathecae of Gyruulus. Shading representsorange contents presumed to indicate
sexual activity. Shell diameters given in brackets. A-M, G y r d u s costulatus: A-I, Mhlangana
river at Avoca, Durban (3.6-5.9 mm); J, K , North Kaap river, East Transvaal(4.6mm); L, M,
Umzumbe, Natal (4.3, 4.7 mm). N, 0, C. connoUyi sp. mv.: N, Tsolo district, East Cape
(4.5 mm); 0, Sabie, East Transvaal(4.4 mm).
The anatomy of CyrauEUs constulatus has been described previously for animals from
Mozambique (De Azevedo et uZ., 1957), Angola (Wright, 1963), Leopoldville Congo
(Medeiros, 1964), West Cameroon (Wright, 1965)and Ethiopia (Brown, 1965). Those
THE MOLLUSCAN GENUS G YR4ULUS
315
accounts differ from the present description of South African material only in apparently
minor details, e.g. Wright (1963)found that the penis extended well into the preputium,
and Brown (1965) found no more than three prostatic lobes in large animals.
II
HD
0 5rnm
AG
L_____
Olmm
I
I
FIGURES
10 to 13. 10, 11, Junction of male and female systems in Gyruulus costulatus from
Mhlangana river at Avoca, Durban: 10, left side; 11, ventral side, i.e., that which is nearest to
the columella muscle. 12, Seminal vesicles of three animals of G. connoUyi sp. nov. from
Tsolo district, East Cape. Hermaphrodite duct leading to ovotestis on the left of figure. 13, G.
connollyi from Vereeniging, West Transvaal. Dorsal view of anterior part of dissected animal
showing organs in situ.
Material examined. Shells. Republic of South Africa, Swaziland and Caprivi Strip ;
493 samples comprising about 5250 snails deposited in the Institute for Zoological
Research, University of Potchefstroom (locality details are available); 78 samples
comprising 900 snails, some deposited in the British Museum (Natural History) (see
Appendix). Southern Mozambique : Vila de Joao Bello (IZP 11.19.67); Goba (see
Appendix). Botswana : Maun (IZP 69.6.65). Rhodesia : three samples from Melsetter
and Glen Clova districts (see Appendix).
316
D. S. BROWN AND J. A. VAN EEDEN
Anatomy. Mhlangana river at Avoca near Durban, Natal (BMNH 1969.16, 13
animals); Umzumbe, Natal (IZP 30.16.67, 13 animals); North Kaap river, Barberton,
Eastern Transvaal (IZP 68.35.66; BMNH 1969.22, 18 animals) ; Olienhoutspruit,
Johannesburg (IZP 22.7.66, two animals).
Distribution.Eastern and northern regions of the Republic of South Africa ;Mozambique ; Rhodesia ;Angola ; northwards to Ethiopia and the Sahara.
FIGURES
14 and 15. Central tooth and half transverse row of radula: 14, G y r d u coshrlatus
from North Kaap river, East Transvaal ;15, G. connoUyi sp. nov. from Sabie, East Transvaal.
Diameter of both snails 4.4 mm.
Gyraulus connollyi sp. nov.
Planorbis cminrlum Connolly : Cawston, 1924,14. Nomen nudum.
Planorbis (Gyraalus)lamyi: Connolly, 1939,489. Non Planorbis lamyi Germain, 1905,
256; 1908,638.
Planorbis (Gyraulus)lamyi var. albida Connolly, 1939,490.
Gyraulus Iamyi: Brown, 1967,482. Non Planorbis lamya Germain, 1905,256.
THE MOLLUSCAN GENUS GYRAULUS
..
.
a/b
3 O I
31 7
8
0..
4
0
0
0
0 . .
0
0
25
0
.'.s.2.
...A
0
* o
0
0
0
0.0 0 0 0
000
0
08 0 0 0
03 0?905?+0
000
0
0
0
20
20
15
10
5
a/b
FIGURE
16. A, Scatter diagram for a / b in relation to u for a sample of shells containing Gyraulus
costulatus ( 0 ) and G. connoUyi sp. nov. (0)
from the Klein Jukskei river, Johannesburg.
Shells having total diameter between 3 and 5 mm are distributed between the arrows near the
abscissa. B, Frequency distributionof the values of ulb plotted in A and of G. connollyi from
Upington district, North Cape Province.
318
D. S. BROWN AND J. A. VAN EEDEN
Types and type locality. Holotype (BMNH 1969.4). Twenty dry paratypes and 17
paratypes in spirit (BMNH 1969. 5 and 6) : 20 paratypes in spirit (IZP 21.3.66).
Vereeniging, Transvaal Republic of South Africa; dam on farm Witkop (no. 174,
SouthAfrica 1 :250,OOO topo-cadastralmap sheet 2626). Co-ordinates :26'12' S, 28'45'E.
G. H. Jordaan, September 1965.
Shell (Plate 2A-C). Upper surface of whorls steeply curved with deep suture; early
whorls less deeply sunk above than below (apertnral side). Side of whorl evenly and
slightly curved with periphery near middle. Underside of whorl bluntly angular near
the middle. The whorl is high in relation to its width. Aperture descending to near the
middle of the whorl ; the parietal lip is somewhat thickened, though opaque only at
the margin. Transverse ribs well developed and spaced closely and more or less irregularly. No spiral sculpture.
Dimensions. Holotype: 4.1 mm diameter; ultimate whorl 1.6 mm high at aperture;
3% whorls. The paratypes have the whorl evenly curved at the side and angular
on the under side, showing little variation in these respects. Variation in the relative
height of the whorl is illustrated in Fig. 17. In the smallest shell (2-5 mm diameter)
the aperture descends to some extent, though it descends nearly to the middle of the
whorl in all the large examples. In some shells the parietal lip of the aperture is thickened
and nearly opaque, but in others the callous is entirely undeveloped. The smallest
paratype; 2.5 mm diameter, 2%whorls. Largest paratype; 4.6 mm, four whorls. Eleven
other paratypes of 4.0 mm or more complete 3+3$ whorls.
Diagnosis. Gyraduus connollyi is distinguished from other members of this genus
occurring in the Ethiopian region by the steeply curved to angular underside of the
whorl, the slightly curved side of the whorl, the well developed transverse sculpture
and the near absence of spiral sculpture.
Shellsfrom 0 t h localities. Variation in the descent of the ultimate whorl produces
corresponding variation in the depth and width of the umbilicus. The aperture does
not usually descend far below the middle of the whorl and only a single scalariform shell
was obtained (Plate 2F). The periphery is usually slightly curved, though in some
examples it is bluntly angular (Plate 21, J). In some populations the angulation on the
underside of the whorl is more acute (Plate 2G,H) than in the type series; in some other
populations the angulation is visible only at the beginning of the ultimate whorl that
is elsewhere steeply curved. As in G. costulatusthe relative height of the whorl decreases
with increase in shell size (Figs 16 and 17). Very fine and irregular spiral lines are
present on some parts of some shells.
Anatomy. This is similar to that of Gyruuhs costuhtus. Pigmentation is concentrated
in the tentacles and at the edge of the kidney, and is nearly absent from the left side of
the mantle. The anus opens at the base of a dorsal lamella on the pseudobranch, and a
rectal ridge runs posteriorly for a short distance. The copulatory organ does not extend
posteriorly as far as the prostatic lobes (Fig. 13) and reaches a length of about 1-8mm
in large animals (5 mm diameter) ;the penis sheath is usually shorter than the preputium
(Fig. 7E-H, PS/PR = 0.5-1.0). The penis extends to near the diaphragm and the
stylet resembles that of G. costulatus.A maximum of about 12 prostatic lobes of irregular
size and arrangement were observed (Fig. 8). The spermatheca is elongate club-shaped
(Fig. 9N, 0); seminal vesicle variable in shape with the proximal part best developed
T H E MOLLUSCAN GENUS
GYRAULUS
;'-tI
319
30
O/b
0
I
B
1.8
20
22
24
26
28
30
32
--z?lLLAL
34
36
3
8
4.0
4.2
a/ b
FIGURE
17. A, Scatter diagram for a/b in relation to a for Gyruuluscostulatus ( 0 )from the North
Kaap river, East Transvaal, and for the type series ofC.connoUyisp.nov. ( 0 )fromvereeniging,
West Transvaal. A few values for G. costulatus from other localities near the Natal coast (Avoca
(A)and Umzumbe (A)) are included. Shells having a total diameter between 3 and 5 mm are
distributed between the arrows near the abscissa. B, Frequency distribution of the values of u/b
plotted for the large samples in A.
320
D. S. BROWQ AND J. A. VAN EEDEN
and sometimes consisting of lobes with orange contents (Fig. 12). Ovotestis with up to
12 lobes arranged in two rows.
Radulae were examined from three paratypes (4.0 mm diameter) and ten snails
(4.1-4-4 mm) from Sabie, Eastern Transvaal (Fig. 15). There seem to be no significant
differences between radulae from the different localities. The central tooth has two
more or less symmetrical cusps, the numbers of teeth in each half transverse row are
15 or 16 (paratypes) and 13-17 (Sabie), and the transition between the laterals and the
marginal occurs between the 9th and 11th teeth. In some rows the cusps appear
somewhat narrower or broader than those illustrated, and the cusps are considerably
longer and sharper in teeth that are displaced from the position usually obtained in
preparations.
Comparison with Gyraulus costulatus: the underside of the whorl is very steeply
curved or angular in G. connollyi, whereas it is less curved and never angular in G.
costuhtus. The periphery of conndlyi is usually evedy curved and is never acutely
angular, while the periphery of costulutus is usually bluntly to acutely angular. A
peripheral fringe of periostracum is apparently not developed in conndljti, and in that
species the transverse ribs are usually not so widely or so regularly spaced as in
costulutus.
There is a significant difference in the relative height of the whorl between the type
series of G. conndlp’ and a sample of G. costulutusfrom the North Kaap river, Eastern
Transvaal (Fig. 17); distributions of u/b for each species are distinct for shells of more
than 3-0 mm diameter. The bimodal frequency distribution of u/b for costulutus in
Fig. 17 is due to concentrations of individuals near the upper and lower limits of the
size range. Differences in the relative height of the whorl also serve to distinguish,
though less clearly, the two species in a mixed sample from the Klein Jukskei river
system near Johannesburg (Plate 1E,F,H, I, J-M;Fig. 16) ;in this sample identifications were made initially according to the shape of the underside of the whorl. The
secondary peak in the frequency distribution of a/b for costuhtus in Fig. 16 is probably
due to non-random sampling in favour of large snails. However, although connollp~
and costulutus collected from the same locality, or from different places, may usually
be distinguished by reference to the relative height of the whorl, some populations of
connollyi have a whorl no higher than it is in some examples of costulatus. For example
the frequency distribution of u/b for shells from the Upington district, Northern Cape
(IZP 59.82.64) identified as conndlyi according to their steeply curved to angular
underside (Plate 21,J)is completely overlapped by the values for costulutur from the
Klein Jukskei river (Fig. 16).
Cmpurisson with other African Gyraulus: Connolly (1939) stated that the type of
Gyuulus lumyi (Germain) was deposited in the Paris Museum but it has unfortunately
not been possible to obtain the specimen or a recent photograph of it. The description
(Germain, 1905, 1908) was based on two shells and apparently no additional material
has been reported in the literature. The description (Germain, 1908: 638) reads
(translated from the French) :‘Shell small,flattened, fairly thick, finely and irregularly
striate, slightly convex above, with a large and funnel-shaped umbilicus beneath ;
four convex and rapidly increasing whorls separated by a deep suture ;last whorl very
large, scarcely dilated towards the aperture, rather rounded, giving a false impression
THE MOLLUSCAN GENUS GYRAULUS
321
FIGURE
18. Map of southern Africa Showing the distribution of oytmrlus corhrlohu ( 0 ) and
C. co1uIoLlyt sp. nov. ( 0 )in 1 /16th degree rquare loci (25 km or 15 miles square).
of a carination at the base; aperture very oblique, a rounded oval with a fairly marked
lower angulation; peristome simple and almost continuous, joined at the edges by a
conspicuous white callosity.’
20
32.2
D. S. BROWN AM, I. A. VAN RXDBN
In identifying South Africanshells ILS G. Imrryi, Connolly(1939) presumably attached
importace to a supposed resemblance in the shape!of the whorl, which he described
as 'well rounded at periphery, almost bluntly carinate beneath'. However, Gennain
did not publish a profile view and his illustration of the underside does not clearly show
the shape of the whorl. G. kmyi completes four whorls at 3.5 mm diameter and is
seemingly a d e r form thanG. connoZZyi; which in the type series completes only
33-32 whorls at 4-0 mm diameter. G. Zumyi was orighlly described as 'h e l y striate'
whereas the ribs of G. connoZlp. are comparable in thickness to those of G. c o s f u h
(Krauss). Germain (1908) stated that the species most similar to G. Zumyi was G. upmfus
(Von Martens, 1897; Adam, 1957); the latter has a very small umbilicus and seems
to be clearly distinct from G.conno?Zy'. Accordingly, we regard past identifications of
G. b y i in South Africa as incorrect.
The presence of an angulation on the underside of the whorl and the slightly curved
periphery distinguish G.conndZp. from G.c o n c a w Mandahl-Barth (1954, Victoria
Nile), G. spabiZis (Preston, 1912; near Mombasa, Kenya), G. kisumiensis (Preston,
1 9 1 2 ~ Kisumu,
;
Lake Victoria) and G. m u m (Pilsbry and Bequaert, 1927;
Avakubi, Congo), all of which have the whorl more or less evenly curved beneath.
G. k&ezit&s (Preston, 1912 ;Kigezi, South West Uganda) was described as 'somewhat
sharply angled below' but the lower angulation is peripheral and below the middle of
the whorl, and not on the underside of the whorl as in connoZZyt'.
G. cnmw Mandahl-Barth (1954; Entebbe, Lake Victoria) has the whorl relatively
higher even than it is in G. cmndy., and well developed spiral lineswhich are absent in
c o n d j & G. bjcminutus Mandahl-Barth (1954) and G. fuini Adam (1957), both from
Lake Albert, have two or three angulations that are better developed than the lower
angulation i n c d y * .Somespecimens of G. bequaertiAdam (1957) from PleistoceneHolocene deposits near Lake Edward have upper and lower angulations that are better
developed than in CmndZy., and less angular shells seem to be distinguished from
c o n d p ' by their poorly developed transverse ribs.
Material exmnibd. Shell. Republic of South Africa; 649 samples comprising approximately 8240 snails deposited in the Institute for Zoological Research, University
of Potchefstroom (locality data available) ; 24 samples comprising 630 snails, some
deposited in the British Museum (Natural History) see Appendix). Anatomy. Transvaal: Vereeniging (IZP 21.3.66; BMNH 1969.6, three animals); Sabie river at Sabie
(IZP 68.40.66; BMNH 1969.33, ten animals); Olienhoutspruit near Johannesburg
(IZP 22.7.66, one animal). Eastern Cape Province: Inya river, Tsolo district (IZP
1.124.67, ten animals); Mzindlalani river, Flagstaff (IZP 15.97.67, four animals).
Distribution. Known only from the Republic of South Africa (Fig. 18).
Ddwation. Named in honour of the late Major M. Co&oIly.
DISTRIBUTION AND ECOLOGY
The distribution of Gyraulus castu&tus and G. c t m d Y j in loci of 1116th degree
squares (about 25 km or 15 miles square) is shown in Fig. 18. An average of 3 4 samples
have been examined from 354 loci. Although collecting activity bas been concentrated
THE MOLLUSCAN GENUS GYRAULUS
323
near the coast and in the eastern part of South Africa, the small number of positive
loci in the central and western areas also reflects the rarity of aquatic habitats in these
comparatively arid regions.
The southernmost locality known for G. costulatus lies 14 miles north-east of Kei
Mouth, Eastern Cape Province (IZP 105.3.59) and this species occurs in a coastal
strip extending northwards into Natal. In that province the range extends inland,
though the western limits apparently do not exceed an altitude of about 1500 m.
G.costulatus is present in Swaziland and the lower lying parts of the Transvaal, but is
apparently absent from considerable areas of the highveld in the Transvaal and Orange
Free State. This species has been found in the lower course of the Vaal river as far west
asthe Barkly West district (IZP 59.61.64). All specimensof GyrauZus from Mozambique,
Botswana, Rhodesia and the Caprivi Strip have been identified as costulatus. Examples
of costulatus having an acutely angular periphery with a fringe of periostracum have
been obtained most frequently at relatively low altitudes in the range of this species
in South Africa, and it is desirable that the significance of this geographical variation
should be investigated.
G.connollyi unlike G. costulatusis present in Western Cape Province, being known
from as far west as the Caledon district (IZP 79.3.66).G. cmnollyi has been found in
the districts of George, Humansdorp and East London and is far more widely distributed than costulatus in the Eastern Cape Province. However, connolly' has not
been found near the coast in Natal and it is apparently restricted to comparatively
high altitudes; a record of 'G. lamyi' from Reunion (south of Durban) given by
Connolly (1939) probably refers to an example of costulutus with an unusually high
whorl, as conndly', has not been obtained subsequently in that area despite intensive
collecting.
The eastern limit of 'G. lamyi' in Natal has previously been given as a line passing
through Port Shepstone, Greytown, Dundee and Piet Reteif (Brown, 1967), but
connollyi is now known to occur in the Helpmekaar district, to the south-east of Dundee
in tributaries of the Buffaloeriver. Further, the presence of a single specimen that is
apparently condl''
in a sample of costulatus from the Babanango district in
Zululand at an altitude of about 1060 m (IZP 52.168.67), suggests that co)))IoIIy1' may
occur to the east of the main area of its distribution in Natal on isolated areas of high
ground.
G.conndlyihas not been obtained in Swaziland,though it occurson the Drakensberg
escarpment in the eastern Transvaal at least as far north as the Pilgrim's Rest district,
and is widely distributed at moderate to high altitudes in the southern and south-western
regions of that province. It seems to be distributed throughout the Orange Free
State, with the possible exception of the more arid areas. This species has been
found more frequently than costulatiu along the lower course of the Vaal river
and is known from as far west as the Upington district in Northern Cape Province
IZP 59.82.64).
In view of the distribution pattern of G. connollyiin South Africa, it might be expected to occur on highland areas to the north. However, Wright (1963) found onlycostuZutus in the Ganguelas district at about 1500 m on the southern plateau of Angola, and
the first author failed to find connoll''
in the Inyanga, Umtali and Melsetter districts of
20,
D. S. BROWN AND J. A. VAN EEDEN
324
.
15
.
MIDDELBURG
\
FIGURES
19 and 20.19, Map of south-eastem Transvaal and adjacent Mozambique showing the
area where detailed investigation was made of the distribution of G y d u s costulatus and
G. connollyi sp. nov. 20, Distribution of G. costulatus ( 0 )and G. connollyi( A)intheNelspmit
district. Contours in feet (3000 feet = 910 m; 5000 feet = 1515 m ; 6500 feet = 1970 m).
THE MOLLUSCAN GENUS GYRAULUS
325
the eastern Rhodesian highlands in April of 1967 and 1968, although many apparently
suitable streams were searched.
Although G. costulutus and G. connoZZy' are allopatric over extensive areas, their
ranges overlap considerably in South Africa and samplesfrom 56 localities of the present
series contain both species. Distribution and ecology were studied in the Nelspruit
district, Eastern Transvaal, where both species occur in the Sabie, Crocodile and Kaap
river systems that drain from the eastern slope of the Drakensberg escarpment towards
the Indian Ocean (Figs 19 and 20). The terrain below about 900 m (3000 feet) in the
FIGURE
21. Map of southern Africa showing the range of Gyraulus connollyisp. nov.(crosshatched). Fine broken lines indicate areas experiencing average annual frequencies of 5, 30 or
90 days with minimum temperature below 0°C (after Schulze, 1965: Fig. 85, based on 140
stations). The four indentationsin the eastern limit of the range between latitudes 25" and 30"S
correspond from north to south to the valleys of the Komati, Pongola, Tugela and Umgeni
rivers.
vicinity of Nelspruit and further eastwards, known as lowveld, experiences a subtropical climate and citrus fruits are a major crop. To the west, conditions become
cooler with increasing altitude and winters are severe on the plateau or highveld
(1800 m). G. costulutus was found in the lowveld and in the foothills of the escarpment,
and it occurs to the east in the Kruger National Park and southern Mozambique
(Oberholzer and Van Eeden, 1967; De Azevedo et d.,1957). Both species occurred
together in localities near the 3000 feet (910 m) contour (Fig. 20), while connoZZyiwas
found alone in the two localities examined at higher altitudes in the Crocodile and
Elands river valleys. As connollyi also occurs on the plateau, the present observations
suggest that the limit of its range on the escarpment does not descend far below 900 m
or 3000 feet at this latitude (2.5"s). The upper limit for costulutus on the escarpment
may lie at about this altitude, but as this species has been found on the plateau in the
326
t
D. S. JW3” AND J. A, VAN EEDEN
Middelburgand Carolina districts (Fig. 19) between 1500 and 1660 m (5ooo-5500 feet)
it seems that though conditions above M)o m favour c m d y ’ they do not entirely
exclude costukztw.
G. coshrlahrs was obtained in the Nelspruit district in two dams (IZP 9.4.56 ;2.21.60),
but otherwise all the localities shown in Fig. 20 are streams or rivers. In these habitats,
both species occurred on stones or in fringing vegetation and both species were taken
together in the collecting net on several occasions. In other parts of South Africa also,
costulatus and cmd’. occur almost exclusively in flowing waters, or in residual pools
through which water flows for some part of the year ;they have only rarely been found
in small, still bodies of water such as farm dams. The distribution of the two species
in localities examined by the first author is as follows :
G. costulatus (80 localities): small dams (4%); streams (46%); rivers (50%).
G. con&’*
(24 localities): small dams (4%); natural pools (8%); streads (58%);
rivers (30%).
These observationssuggestthat G. costulatw and G.cmndlyido not have significantly
different requirements in respect of their aquatic habitat, and their ranges in South
Africa are apparently not determined by the availability of particular kinds of habitat.
The distribution pattern of c o n d l y i coincides closely with the position of the coolest
part of the South African temperate climatic region (Fig. Zl), suggesting that this
species is intolerant of subtropical or tropical conditions. Four indentations in the
eastern boundary of the range of condi‘’’
correspond to major river valleys, up
which the warm climatic conditions of the coast extend inland. On the other hand, the
distribution pattern of costulatus leads us to conclude that this species is intolerant of
cool conditions. One way in which temperature could influence distribution is suggested
by the experimental work of ShifT (1964) and Sturrock (1966), who demonstrated that
the reproductive potentials of the African freshwater snails Bulinus globosus (Morelet)
and Biomphaluria pfezflmi (Krauss) are profoundly affected by temperature.
DISCUSSION
The occurrence in South Africa of a species of GyrauZus differing from costulatus
Krauss was first recognized by Connolly (unpublished), whose manuscript name
comiculum was given without description by Cawston (1924) and is therefore a nomen
nudum. Subsequently, Connolly (1939) identified this South African form as G. Zamy.
(Germain, 1905), including corniculum in synonymy. Connolly (1939: 489) stated that
costulatus was ‘a well defined species, easily distinguished by its small size and strong
costulation’. These characters are not suitable for diagnosis, though Connolly described
the whorl of costulatus as ‘subangulate at periphery’ and the whorl of lam+ as ‘well
rounded at periphery, almost bluntly carinate beneath’, which are the differences we
have found to be most consistent between costulatw and connolljti sp. nov. Large
pale-coloured examples of G. lamyi having a well developed lower angulation were
described as var. albida by Connolly (1939); seven paratypes (BMNH 1937.12.30.
11565-72) have been examined (Plate 2D, E) and they are not significantly different
from the range of variation we have observed in cmndZyi sp. nov.
THE MOLLUSCAN GENUS GYRAULUS
327
A close phylogenetic relationship between G. costulatus and G. conndlyi is suggested by their anatomical similarity to each other, and the small number of their prostatic
lobes in comparison with species of this genus’that have been described from Europe,
Asia and North America (Baker, 1945 ; Hubendick & Radoman, 1956; Meier-Brook,
1954). The fact that the majority of examples of Cyraulus from southern Africa may be
readily identified as either costulatus or conndly. even though these forms are partly
sympatric and live together, suggests that reproductive isolation is largely effective.
Snails that are possibly of hybrid origin were obtained from the Vrede district, Orange
Free State, in a locality situated about 100 km from the nearest known population of
undoubted costulatus. The side of the whorl is rather angular and there is a fringe of
periostracum, yet these shells resemble c o n d l y ’ in respect of the relative height of
the whorl and the strongly curved underside (Plate 2K, L).
From what is known of the distribution of G.costulatus and G. condly*,there is
a fundamental biogeographical difference between them. The distribution pattern of
costulatus is characteristic of organisms that reach the southern limits of their ranges
in south-eastern Africa and may be referred to as ‘tropical’. This species has a more
extensive range in South Africa than some other tropical freshwater snails (Brown, 1967)
and resembles certain species of Amphibia (Poynton, 1964) in having a south-western
arm of distribution extending down the lower course of the Vaal river. Tropical freshwater organisms apparently do not have comparable southward extensions of distribution in South West Africa, presumably because of the cooling effect of the Atlantic
Ocean, and the low rainfall and rarity of suitable habitats.
G. connollyiis apparently endemic to the Republic of South Africa, and this species
is the f i s t example of a freshwater snail for which there is good evidence of close
association with the temperate climatic region of South Africa. Some other freshwater
molluscs may be restricted to western Cape Province (Brown, 1967:491), but they are
poorly known. It seems likely that some past climatic fluctuation have been great
enough to produce expansions and retractions in the ranges of costulatusand connOzIyi,
and accordingly relict populations of either species could occur where there are ‘islands’
of suitable climate. Evidence has been obtained of isolated populations of G.connollp’
at comparatively high altitudes in central Natal, and the apparent absence of this
species from the mountainous regions of Swaziland and the northern Transvaal needs
to be confirmed. However, in view of the presently known distribution pattern of
conndlyi it seems that the Limpopo river valley has served as an effective barrier to
greater northwards expansion.
The valley of the Limpopo river at the border between the Transvaal and Rhodesia
experiences a warm climate and a low rainfall (Schulze, 1965: Average Rainfall Map,
facing p. 330), and permanent water is rare to the north and south of the river, which
itself undergoes great fluctuations in level. Both species of Gyraulus are associated with
permanent habitats, particularly streams and slow-flowing rivers, and similar preferences have been described for G. costulatus in Angola (Wright, 1963) and Ethiopia
(Brown, 1964); neither species is known to inhabit small, temporary pools. Thus, the
Limpopo valley may constitute a long-standing barrier to both G.costulatus and G.
conndlyi, because of the combined effects of high temperature and scarcity of suitable
habitats. This could account for the absence of G. conndlyi from the Rhodesian
328
D . S . BROWN AND J. A.
VAN EEDEN
highlands, but the dispersal of G. costidatus presumably is not significantly affected by
this barrier as this species occurs on the comparatively well watered coastal plain
of Mozambique.
SUMMARY
G?yraulus costulatus costulatus (Krauss) and G. connollyi sp. nov. ( = Planorbis
(Gyraulus)lamyi Connolly, 1939 non Germain, 1905) differ in respect of conchological
features, though no anatomical differenceshave been detected. The anatomy of topotypical examples of G. costulatus is described. Distribution patterns for the two species have
been established by examination of about 15,000 snails from 1188 localities mostly
situated in the Republic of South Africa. G. costulatus has not been found further southwest than the East London district in Cape Province and is regarded as a member
of the tropical fauna. G. connoll” is apparently endemic to the temperate climatic
region of South Africa and is the only freshwater snail known to have such a distribution
pattern. The lower altitudinal limit of G. conndljti on the Drakensberg escarpment
at latitude 25” S is about 3000 feet (910 m). Both species are usually found in flowing
waters and frequently occur together in the same locality ; their apparent ecological
similarity suggests that the influence of temperature is important in determining their
ranges. The apparent absence of G. connollyi from the Rhodesian highlands could be
due to a barrier to northwards dispersal provided by the hot and dry Limpopo river
valley.
ACKNOWLEDGEMENTS
We thank the South African Council for Scientific and Industrial Research, the
Department of Technical Agricultural Services of South Africa, and the Medical
Research Council of the United Kingdom for supporting the study of freshwater snails
in South Africa, and the many collectors who have contributed the material that has
made possible the present paper. The first author is indebted to Professor J. A. Van
Eeden for accommodation in the Institute for Zoological Research, University of
Potchefstroom from 1966 to 1968, and for the opportunity of examining the snail
collection stored there. We are grateful to Mr D. Claugher of the Zoology Department,
British Museum (Natural History) for preparing photographs.
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10: 447-528.
WRIGHT, C. A., 1965. The freshwater gastropod molluscs of West Cameroon. Bull. BY.Mus. nut. Hist.
(ZOO/!.),
13: 73-98.
WRIGHT,C. A. & BROWN,
D. S., 1962. On a collection of freshwater gastropod molluscs from the Ethiopian
Highlands. Bull. BY.Mus. nut. Hist.(Zool.), 8: 285-312.
KEY T O FIGURE LETTERING
PN
albumen gland
PR
anus
PRO
buccal mass
PS
cerebral ganglion
R
diaphragm
RM
dorsal lamella
RR
foot
sc
hermaphrodite duct
SD
male aperture
SG
cut edge of mantle
SP
nidamental gland
ST
OD oviduct
sv
ov ovotestis
T
pseudobranch
P
VA
PA papilla
PE penis
VD
PL preputium lumen
AG
AN
BM
CG
D
DL
F
HD
MA
ME
NG
pneumostome
preputium
prostatic lobes
penis sheath
rectum
retractor muscle
rectal ridge
sperm canal
sperm duct
salivary gland
spermatheca
stylet
seminal vesicle
tentacle
vagina
vas deferens
330
D.
S. BROWN AND J. A. VAN EEDEN
APPENDIX
Localities for specitnens deposited in the British Museum (Natural History) ; unless stated othcrwke,
collected in the Republic of South Africa by D. S. Brown. Collector’s number preceded by DS3; IZP
precedes a c d numbere of other examples deposited in the Institute for Zoological R d ,
University of Potchefstroom.
GyraUIUS costu&atuc ( b u s s )
Ingwavuma, northern Natal. Leg. P. B. van Dyk. 24 Jul. 1967. IZP 53.46.67;BMNH 1969.1.
Carolina, Transvaal. Leg. G. H. Jordaan. 30 Sep. 1965.IZP 1.20.66; BMNH 1969.2.
Klein Jukskei river system, Johannesburg, Transvaal. Leg. G. H. Jordaan. Oct./Nov. 1965.IZP 22.7.66;
BMNH 1969.3.
Nels river, Nelspruit, Eastern Transvaal. 8. Oct. 1963.DSB 1; BMNH 1969.12.
Sand river, Newington, Eastern Transvaal. Sep. 1963.DSB 9;BMNH 1969.13.
Letaba river, Tzaneen, N-E. Transvaal. 26 Oct. 1963. DSB 30;BMNH 1969.14.
Hattingspruit Dam,Dundee, Natal. 10 Dec. 1963.DSB 40;BMNH 1969.15.
Mhlangana river at Avoca, Durban, Natal. 16 Jan. 1964.DSB 68;BMNH 1969.16.
Mlaxi river, Camperdown, Natal. 10 Feb. 1964.DSB 78;BMNH 1969.17.
Umzimkulwana river, Harding district, Natal. 28 Feb. 1964.DSB 160; BMNH 1969.18.
Mfule river, Melmoth, Natal. 13 Aug. 1964.DSB 374;BMNH 1969.19.
Umkobeni river, Richmond district, Natal. 20 Aug. 1964.DSB 389;BMNH 1969.20.
Rio Umbeluzi, Goba district, Mozambique. 29 Sept. 1964.DSB 471; BMNH 1969.21.
North G a p river, Barberton district, S-E. Transvaal. Jul. 1966. IZP 68.35.66;BMNH 1969.22.
Quarry Road, Umgeni valley, Durban, Natal. 3 Mar. 1964.DSB 164;BMNH 1969.23.
Gyraulus connollyi sp. nov.
Vereeniging (Witkop, Farm 174), Transvaal. Leg. G.H. Jordaan. Sept. 1965. IZP 21.3.66; BMNH
1969.4. Holotype.
Vereeniging (Witkop, Farm 174), Transvaal. Leg. G. H. Jordaan. Sep. 1965. IZP 21.3.66; BMNH
1969.5 & 6.Paratypes.
Klein Jukskei river system, Johannesburg, Transvaal. Oct./Nov. 1965.Leg. G. H. Jordaan. IZP 22.7.66;
BMNH 1969.1969.7.
Pilgrim’s Rest, Eastern Transvaal. 22 Sep. 1963.DSB 16;BMNH 1969.8 & 24.
Kentani, Eastern Cape Province. Leg. P. J. Geldenhuys. 23 Sep. 1966. IZP 5.54.67;BMNH 1969.9.
Upington district, Northern Cape Province. Leg. G. H. Jordaan. 30 Apr. 1967. IZP 59.82.64;BMNH
1969.10.
Richmond district, Natal. 25 Feb. 1964.DSB 136;BMNH 1969.25.
Zoetmelk river, Utrecht district, Natal. 8 Apr. 1964.DSB 215;BMNH 1969.26.
Volksrust, Natal. 9 Apr. 1964.DSB 228;BMNH 1969.27.
Horn river, Newcastle district, Natal. 10 Apr. 1964.DSB 235;BMNH 1969.28.
Kokstad district, Eastern Cape Province. 15 Apr. 1964.DSB 246;BMNH 1969.29.
Bleomendal river, Rietvlei, Natal. 1 Nov. 1964.DSB 493;BMNH 1969.30.
Ladysmith, Natal. 2 Dec. 1964.DSB 511; BMNH 1969.31.
Sani Pass Hotel, Natal. 6 Dec. 1964.DSB 529;BMNH 1969.32.
Sabie river, Sabie, Eastem Transvaal. 19 Jul. 1966. IZP 68.40.66;BMNH 1969.33.
Gyradus connollyi ?
Vrede district, Orange Free State. Leg. P. J. Geldenhuys. 6 Feb. 1968.IZP 17.62.68; BMNH 1969.11
Plate 1
B
D
F
L
K
-
M
2mm
*
( F n c i n g p . 330)
Plate 2
Zool. J . Linn. SOC.,48 (1969)
2 mm
BROWN
AND
VAN EEDEN
THE
MOLLUSCAN GENUS GYRAULUS
331
EXPLANATION O F PLATES
PLATB
1
Gyroulus costuktus (Krause). Shells from South Africa
A, B. Ingwavuma, Natal. Example with peripheral fringe. BMNH 1969.1 ; IZP 53.46.67.
C,D.Caroline,Transvaal. BMNH 1969.2; IZP 1.20.66.
E,F.Klein Julrslrei river, Johannesburg, Transvaal. Small example. BMNH 1969.3 ; IZP 22.7.66.
G. Original illustrationof Plunorbiscostulutus copied from Krauss (1848 :P1.5, Fig. 8. Scale line represents
6 m).
J, K. Klein Jukskei river, Johannesburg, Transvaal. Large example BMNH 1969.3; IZP 22.7.66.
Gyraulus connollyi sp. nov. Shells from South Africa
H, I, L,M. Klein Jukskei river, Johannesburg, Transvaal. Small and large examples. BMNH 1969.7;
IZP 22.7.66.
PLATE2
Gyraulus connollyi sp. nov. Shells from South Africa
A-C. Holotype. Vereeniging,Transvaal. BMNH 1969.4; IZP 21.3.66.
D,E. Glen, Orange Free State (‘Planorbislamyi Germain’ var. ulbida Connolly, 1939. Paratype, BMNH
1937.12.30.11565).
F. Pilgrim’s Rest, E. Transvaal. Scalariform example. BMNH 1969.8.
G, H.Kentani, E. Cape Province. BMNH 1969.9; IZP 5.54.67.
I, J. Upington district, Northern Cape Province. BMNH 1969.10; IZP 59.82.64.
Gyraulus connolly‘ 2
X,L.Vrede district, Orange Free State. Example with peripheral fringe. BMNH 1969.11 ;IZP 17.62.68.
Photographedshells deposited in British Museum (Natural History) (BMNH). Other material deposited
in Institute for Zoological Research, University of Potchefstroom (IZP).