Revision of Chondrocyclus s. l. (Mollusca: Cyclophoridae), with description of a new genus and twelve new species
Author
Cole, Mary L.
East London Museum, P. O. Box 11021, Southernwood, 5213, South Africa and Department of Zoology and Entomology, Rhodes University, P. O. Box 94, Grahamstown (Makhanda) 6140, South Africa.
marybursey@elmuseum.za.org
text
European Journal of Taxonomy
2019
2019-10-22
569
1
92
journal article
10.5852/ejt.2019.569
ee4333ce-4fde-4a61-85e9-effa3d1b5999
2118-9773
3517522
79BE13FC-B840-4C39-8D25-3328BDCC44D2
Chondrocyclus trifimbriatus
Connolly, 1929
Figs 15
,
16A
Chondrocyclus trifimbriatus
Connolly, 1929: 241
, pl. xiv, figs 35–39 (
type
loc.: Karkloof, bush behind Karkloof Falls [Falcon]).
Chondrocyclus trifimbriatus
–
Connolly 1939: 538
. —
Herbert & Kilburn 2004: 92
.
Diagnosis
Shell small, depressed, lenticular; periostracum with dense axial costae developing five rows of flanges on last whorl: just below suture, at periphery, around umbilicus and two weaker rows on either side of periphery; operculum duplex, exterior portion shallowly concave with step-shaped multispiral lamella terminating in a long solid fringe reflexed over peristome; radula with three large cusps on second lateral tooth, cusps of rachidian, first and second lateral teeth fairly uniform in size; penis flattened dorsoventrally and laterally expanded on left side from about midway down the shaft, intromittent organ relatively long.
Etymology
The specific name is derived from the Latin ‘
tres
’, meaning ‘three’, and ‘
fimbriae
’, meaning ‘fringe’, with reference to the three spiral cords of compacted flange-like bristles on the last whorl.
Type
material examined
Holotype
SOUTH AFRICA
–
KwaZulu-Natal
[Natal] • Karkloof, Natal; presented by W. Falcon; NHMUK 1928.3.16.5. (
Fig. 15A
)
Other material examined
SOUTH
AFRICA
–
KwaZulu-Natal
•
6 specimens
;
Karkloof River valley
, southwest of ‘
The Start’
;
29.3150° S
,
30.250° E
;
1350 m
a.s.l.
;
W. Falcon
coll.;
NMSA
A
8000
•
2 specimens
;
Nkandla Forest Reserve
,
Chibini area
, scarp forest;
28.7227°S
,
31.1282°E
; ±
1200 m
a.s.l.
;
20
Oct. 2003
;
D. Herbert
,
M. Bursey
and
T
. Nangammbi
leg.; under logs and in leaf litter;
NMSA
W
1115
•
1 specimen
;
Entumeni Forest
,
7 km
west of
Eshowe
;
28.8852°S
,
31.3797°E
;
680 m
a.s.l.
;
29
Oct. 2010
;
M. Cole
leg.;
ELM
D16966
•
1 specimen
; same collection data as for preceding;
ELM
W
3692
•
1 specimen
; same collection data as for preceding;
13
Jan. 2010
;
ELM
D17003
•
3 specimens
; same collection data as for preceding;
ELM
W03661
.
Description
SHELL (
Fig. 15
A–C). Small, depressed, lenticular, adult diameter
3.9–4.37 mm
(
4.37–5.32 mm
Entumeni population), height
1.95–2.66 mm
(
2.39–2.86 mm
Entumeni population), diameter:height 1.65–2.0 (
1.62–2.02 mm
Entumeni population) (n = 5
C. trifimbriatus
from
type
locality; n = 6 Entumeni population). Spire not much raised, protoconch sub-mammillate (
Connolly
1929
). Embryonic shell two whorls, microscopically malleate, junction between embryonic shell and teleoconch evident with development of costae on teleoconch. Teleoconch comprising 2.75 whorls, convex, rapidly increasing, suture deeply impressed. Aperture circular, last whorl descending near aperture, peristome simple, continuous and free. Umbilicus wide and deep, exposing all the whorls. Periostracum glossy, honeybrown and lacquer-like with dense lamellate axial costae at regular intervals, approx. 150–155 (n = 4) on last whorl in specimens from the
type
locality, but varying between populations (see Remarks below), expanded into quadrangularly-shaped flanges at periphery, immediately below the suture and around the umbilicus, the row at the periphery the strongest, and with two less prominent rows of lower-standing flanges on either side of periphery. Shell translucent, glossy, corneous yellow-brown when fresh.
LIVING ANIMAL. Creamy white with slight pigmentation on tentacles.
OPERCULUM (
Fig. 15D, F
). Duplex, lamella of outer multispiral portion with 4.25 whorls, step-shaped; on outer surface of lamellar blade a long, solid fringe curves upwards and then outwards forming a groove between fringe and lamellar blade, spanned by a very loose network of bristles; a very short solid horizontal fringe emanates just below main fringe; upper edge of lamella thin and projects above fringe in side view; outer surface of lamellar blade tuberculate at high magnification.
RADULA
(
Fig. 15E
). Rachidian with five cusps, approx. equivalent length; first and second lateral teeth similar, each with five cusps, first three cusps approx. equivalent in size, the fourth very small and the fifth (from centre) vestigial; cusps increase in size very slightly from central tooth outwards, but there is not a large difference in size between cusps.
PENIS (
Fig. 15G
). flattened dorsoventrally and laterally expanded on left side from about midway down the shaft, with numerous annular rugae, smooth distal end narrows, intromittent organ relatively long.
Distribution and habitat
Originally known only from Karkloof River Valley, downstream of Karkloof Falls, but the species appears to have disappeared from the Karkloof vicinity (
Fig. 16A
). Specimens recently discovered at Entumeni and Nkandla forests are considered here to be
C. trifimbriatus
based on comparison with
type
material.
No habitat data available for original specimens, but indigenous Eastern Mistbelt Forest (
von Maltitz
et al.
2003
) occurs in the Karkloof vicinity. Recently collected specimens occur in Scarp forests (Entumeni) and Mistbelt/Scarp (Nkandla) in leaf litter.
Remarks
There are morphological differences between populations from different localities. Specimens from Entumeni (
Fig. 15
B–C) lack the spiral row of flanges just below the suture and the weak row below the periphery. Specimens from Nkandla also bear fewer spiral cords than
C. trifimbriatus
: there is a spiral cord just below suture and one between periphery and umbilicus but the weak cords on either side of periphery are absent. Although not many specimens were available to measure (four from Karkloof, six from Entumeni and two from Nkandla), D:H ratio is similar throughout but the axial costae on last whorl are more dense in Entumeni specimens (approx. 200) and less dense in Nkandla specimens (117) compared to
150–155 in
Karkloof specimens. The opercula of specimens from Entumeni and Nkandla are similar to the operculum of
C. trifimbriatus
from the
type
locality (
Fig. 15D
). The radulae of all populations agree with the descriptions and figure of
Connolly (
1929
,
1939
).
Fig. 15.
Chondrocyclus trifimbriatus
Connolly, 1929
.
A
. Holotype (NHMUK 1928.3.16.5).
B
. Dorsal view (ELM W3661).
C
. Ventral view (ELM W3661).
D, F
. Operculum (NMSA A8000).
E
. Portion of radula (ELM W3661).
G
. Penis, dorsal view (NMSA W1115). Scale bars: A = 3 mm; B–C = 2 mm; D, F–G = 500 µm; E = 20 µm.
Fig. 16.
Distribution map of
Chondrocyclus
species in the Eastern clade.
A
. Species in KwaZulu-Natal and the eastern half of the Eastern Cape, on the coast and extending inland.
B
. Species on the Eastern Cape coast. Note that the range of
C. pondoensis
sp. nov.
overlaps with that of
C. putealis
Connolly, 1939
and
C. cooperae
sp. nov.
T indicates type localities. Major cities and rivers are labelled.
Few specimens were available for study since they seemed to be very rare in the two forests where they were found, and more sampling from these and other forests in north-central
KwaZulu-Natal
are required to resolve more conclusively whether
C. trifimbriatus
occurs throughout the region or whether there may be additional narrow-range species. The only localities represented in the molecular study were Entumeni and Ngome (considered to contain a separate species,
C. pulcherrimus
sp. nov.
). The highly fragmented forests of north-central
Kwazulu-Natal
contain many examples of species, in unrelated taxa, with extremely narrow distributions (e.g.,
Huber
2003
;
Herbert & Kilburn
2004
;
Tilbury & Tolley
2009
) suggesting that the observed morphological differences between populations may indicate undescribed species.