Afrocyclus potteri, Cole, 2019

Cole, Mary L., 2019, Revision of Chondrocyclus s. l. (Mollusca: Cyclophoridae), with description of a new genus and twelve new species, European Journal of Taxonomy 569, pp. 1-92 : 70-71

Afrocyclus potteri gen. et sp. nov.

urn:lsid:zoobank.org:act:AD0079D7-605D-45DE-BCB6-3FF2E9E9349D

Figs 11 C–D, 28C, 29, 31

Diagnosis

Shell very small, depressed, discoidal; periostracum with widely-spaced axial costae producing spiral rows of simple hairs; protoconch strongly malleate; operculum very fragile and duplex, exterior portion very shallowly concave, with low multispiral lamella terminating in a solid fringe, radula with two large cusps on second lateral tooth and rachidian tooth with serrated upper edge.

Etymology

Named for Neil Potter, for his interest in and conservation of flora and fauna on his farms in the Kei River Valley. His family, Carmen, Dylan and Morgan, assisted with fieldwork.

Type material examined

Holotype

SOUTH AFRICA – Eastern Cape • Moonstone Farm, Kei River valley , NNE of Stutterheim, top of mountain, forest at base of sheer krantz; 32.2565° S, 27.5688°E; 1175 m a.s.l.; 24 Apr. 2018; M. Cole and N. Potter leg.; in leaf litter; NMSA P1125 /T4283. ( Fig. 11 C–D)

Paratypes

SOUTH AFRICA – Eastern Cape • 13 specimens; same collection data as for holotype; ELM D18354/ T182 • 5 specimens; same collection data as for holotype; ELM W4052 /T183 • 1 specimen; same collection data as for holotype; NMSA P1143 /T4314 • 1 specimen; same collection data as for holotype; NHMUK 20180585 • 1 specimen; same collection data as for holotype; NHMUK 20180586 • 1 specimen; same collection data as for holotype; NMW.Z.2019.004.00005 • 1 specimen; same collection data as for holotype; RMNH.MOL.340757 • 13 specimens; same collection data as for holotype; 7 Apr. 2005; M. Bursey leg.; ELM D14656/T184 • 2 specimens; same collection data as for holotype; NMSA P1142 /T4313 • 1 specimen; same collection data as for holotype; NMW.Z.2019.004.00004 • 1 specimen; same collection data as for holotype; RMNH.MOL.340756 • 11 specimens; same collection data as for holotype; 19 Dec. 2012; M. and K. Cole leg.; ELM D17097/T185 • 10 specimens; Kambi Forest, Langeni area ; 31.4662°S, 28.6156° E; 19 Jan. 2017; M. Cole and R. Cawood leg.; ELM D18233/ T186 • 3 specimens; Kambi Forest, Langeni area ; 31.4680°S, 28.5893°E; 25 Jan. 2013; M. Cole and V. Ndibo leg.; ELM D17151/T187 • 13 specimens; Kambi Forest, west of Mthatha, Afromontane forest ; 31.28. 1°S, 28.35. 4°E; 1200 m a.s.l., 24 Apr. 1999; D. Herbert leg.; in leaf litter; NMSA V7161 /T4289 • 2 specimens; Baziya Block A(3); 31.5701° S, 28.4224° E; 15 Jan. 2017; M. Cole and R. Cawood leg.; ELM D18183/T188 • 1 specimen; Baziya Forest, west of Mthatha ; 31.32°S, 28.24° E; 15 Jul. 2001; C. Symes leg.; in leaf litter; NMSA V9359 /T4288 • 2 specimens; Baziya Forest, Langeni area , large block of indigenous forest; 31.31.250°S, 28.24.738°E; 19 Feb. 2006; D. Herbert and L. Davis leg.; in leaf litter; NMSA W3973 /T4294 • 2 specimens; Langeni ; 31.47° S, 28.45°E; 18 Feb. 2006; M. Bursey leg.; ELM D14713/T189 • 1 specimen; Langeni, Nocu forest , large block of indigenous forest; 31.4222° S, 28.4984° E; 840 m a.s.l.; 18 Feb. 2006; D. Herbert and L. Davis leg.; in leaf-litter; NMSA W3929 /T4293 • 2 specimens; same collection data as for preceding; 18 Feb. 2006; M. Bursey leg.; ELM D14704/T190 • 3 specimens; Langeni, Jenca Valley , small piece of indigenous forest in rocky valley, above escarpment; 31.21.956° S, 28.33.436°E; ca 1420 m a.s.l.; 18 Feb. 2006; D. Herbert and L. Davis leg.; in leaf-litter; NMSA W3933 /T4292 • 2 specimens; same collection data as for preceding; NMW.Z.2019.004.00006 • 4 specimens; same collection data as for preceding; M. Bursey leg.; ELM D14710/T191 • 1 specimen; Langeni , below aerial road; 31.4754°S, 28.4418°E; 18 Mar. 2006; M. Bursey leg.; ELM D14811/T192 • 14 specimens; Langeni Forest west of Umtata , afromontane forest; 31.23. 9°S, 28.33. 3° E; 1200 m a.s.l.; 24 Apr. 1999; D. Herbert leg.; in leaf-litter; NMSA V7063 /T4290 • 2 specimens; same collection data as for preceding; RMNH.MOL.340758 • 13 specimens; same collection data as for preceding; 31.24. 3° S, 28.32. 7°E; NMSA V7178 /T4291 • 3 specimens; same collection data as for preceding; NHMUK 20180587 .

Other material examined

SOUTH AFRICA – Eastern Cape • 1 specimen; Baziya Block B (2); 31.5433°S, 28.4196°E; 14 Jan. 2017; M. Cole and R. Cawood leg.; ELM D18163 .

Description

SHELL ( Fig. 31 A–C). Very small, depressed, discoidal, adult diameter 2.17–3.51 mm, height 1.02– 1.68 mm, diameter:height 1.7–2.41 (n = 45). Spire low, each whorl just rising above the next, apex mammillate and slightly tilted ( Fig. 31A ). Embryonic shell ( Fig. 28C ) just under 2.5 whorls, strongly malleate, junction between embryonic shell and teleoconch evident with development of axial costae on teleoconch. Teleoconch comprising two whorls, very rapidly increasing, convex, suture impressed. Aperture circular, last whorl descending steeply nearing aperture, peristome simple, continuous and free. Umbilicus very wide, exposing all the whorls ( Fig. 31C ). Periostracum glossy and lacquer-like with well-spaced lamellate axial costae at regular intervals, the number on last whorl varying between 31 and 67 ( Table 5), which produce six–ten spiral rows of simple hairs; intervals between costae with approx. 15–20 microscopic axial threads. Shell translucent when fresh.

OPERCULUM ( Fig. 31F ). Very fragile and duplex, outer portion consists of multispiral lamella with 5.25 whorls, height of lamellar blade very low and thus operculum is very shallowly concave to almost flat, thickened horizontal ridge on lamellar blade just above disc surface; long fringe of fused bristles emanates from this ridge, fused to blade and then curving outwards, leaving no furrow between fringe and vertical portion of blade, fringe of each whorl does not appear to be fused to lamella of following whorl, fringe of outer whorl does not overlap the disc; inner portion of operculum is a thin disc, without a prominent tubercle in centre.

RADULA ( Fig. 31G ). Rachidian with five cusps set a little distance below upper edge of tooth, upper edge slightly serrated, central cusp very long; first lateral tooth with four cusps and a vestigial fifth, third cusp (from centre) very long; second lateral tooth with two large cusps, second cusp (from centre) larger, a third small cusp and a vestigial fourth.

PENIS ( Fig. 31H ). Shaft more or less cylindrical.

Distribution and habitat

Medium altitude forests of the ‘first escarpment’ in the interior of the Transkei region of the Eastern Cape and Kei River Valley. Transkei Mistbelt Forest ( von Maltitz et al. 2003) ( Fig. 29 ).

Remarks

Populations in the geographically disjunct areas of central Transkei and Kei River Valley formed a very well-supported clade, although populations in the two areas were morphologically distinct ( Fig. 31 D– E). Specimens from the type locality on the west side of the Kei River Valley are readily distinguished by very widely-spaced axial costae and relatively short periostracal hairs. The protoconchs of specimens from both areas were relatively large (approx. 750 µm) and more strongly mammillate than in any other species of Afrocyclus gen. nov.

It has been suggested that recent migration may have been facilitated by more extensive forest cover along the inland Transkei mistbelt during the Holocene altithermal ( Hughes et al. 2005) and perhaps some of the more recent altithermals of the Quaternary climatic oscillations ( Partridge 1993; Partridge et al. 1999).

Figures

Fig. 11. Holotypes of species of Afrocyclus gen. nov. A–B. A. oxygala gen. et sp. nov., diameter 2.86 mm (NMSA P0638/T4153). C–D. A. potteri gen. et sp. nov., diameter 2.86 mm (NMSA P1125/T4283). E–F. A. bhaca gen. et sp. nov., diameter 2.87 mm (NMSA P1124/T4282).

Fig. 31. Afrocyclus potteri gen. et sp. nov. A. Dorsal view (ELM D14713). B. Aperture view (ELM W4052). C. Ventral view (ELM D18233). D–E. Juveniles to show variation in detail of axial lamellae of periostracum from different populations: D. Juvenile from type locality (ELM W4052). E. Juvenile from Langeni (ELM D17151). F. Operculum (ELM W4052). G. Portion of radula (ELM W3933). H. Penis, lateral view (ELM W4052). Scale bars: A, C = 1 mm; B, D–E = 500 µm; F, H = 200 µm; G = 20 µm.

Fig. 28. Protoconch detail of species of Afrocyclus gen. nov. A. Afrocyclus isipingoensis (Sturany, 1898) gen. et comb. nov. from Durban (near type locality) (ELM W3648). B. A. oxygala gen. et sp. nov. (ELM W3647). C. A. potteri gen. et sp. nov. (ELM W4052). D. A. bhaca gen. et sp. nov. (NMSA V4889). Scale bars: A–D = 200 µm.

Fig. 29. Distribution map of Afrocyclus gen. nov. T indicates type localities. Provinces and major cities are labelled.