Afrocyclus potteri, Cole, 2019
treatment provided by
gen. et sp. nov.
Afrocyclus potteri gen. et sp. nov.
Figs 11 View Fig C–D, 28C, 29, 31
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.
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
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 View Materials /T4283. ( Fig. 11 View Fig C–D) GoogleMaps
SOUTH AFRICA – Eastern Cape • 13 specimens; same collection data as for holotype; ELM D18354 View Materials / T182 GoogleMaps • 5 specimens; same collection data as for holotype; ELM W4052 View Materials /T183 GoogleMaps • 1 specimen; same collection data as for holotype; NMSA P1143 View Materials /T4314 GoogleMaps • 1 specimen; same collection data as for holotype; NHMUK 20180585 View Materials GoogleMaps • 1 specimen; same collection data as for holotype; NHMUK 20180586 View Materials GoogleMaps • 1 specimen; same collection data as for holotype; NMW.Z.2019.004.00005 GoogleMaps • 1 specimen; same collection data as for holotype; RMNH.MOL.340757 GoogleMaps • 13 specimens; same collection data as for holotype; 7 Apr. 2005; M. Bursey leg.; ELM D14656 View Materials /T184 GoogleMaps • 2 specimens; same collection data as for holotype; NMSA P1142 View Materials /T4313 GoogleMaps • 1 specimen; same collection data as for holotype; NMW.Z.2019.004.00004 GoogleMaps • 1 specimen; same collection data as for holotype; RMNH.MOL.340756 GoogleMaps • 11 specimens; same collection data as for holotype; 19 Dec. 2012; M. and K. Cole leg.; ELM D17097 View Materials /T185 GoogleMaps • 10 specimens; Kambi Forest, Langeni area ; 31.4662°S, 28.6156° E; 19 Jan. 2017; M. Cole and R. Cawood leg.; ELM D18233 View Materials / T186 GoogleMaps • 3 specimens; Kambi Forest, Langeni area ; 31.4680°S, 28.5893°E; 25 Jan. 2013; M. Cole and V. Ndibo leg.; ELM D17151 View Materials /T187 GoogleMaps • 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 View Materials /T4289 GoogleMaps • 2 specimens; Baziya Block A(3); 31.5701° S, 28.4224° E; 15 Jan. 2017; M. Cole and R. Cawood leg.; ELM D18183 View Materials /T188 GoogleMaps • 1 specimen; Baziya Forest, west of Mthatha ; 31.32°S, 28.24° E; 15 Jul. 2001; C. Symes leg.; in leaf litter; NMSA V9359 View Materials /T4288 GoogleMaps • 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 View Materials /T4294 • 2 specimens; Langeni ; 31.47° S, 28.45°E; 18 Feb. 2006; M. Bursey leg.; ELM D14713 View Materials /T189 GoogleMaps • 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 View Materials /T4293 GoogleMaps • 2 specimens; same collection data as for preceding; 18 Feb. 2006; M. Bursey leg.; ELM D14704 View Materials /T190 GoogleMaps • 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 View Materials /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 View Materials /T191 • 1 specimen; Langeni , below aerial road; 31.4754°S, 28.4418°E; 18 Mar. 2006; M. Bursey leg.; ELM D14811 View Materials /T192 GoogleMaps • 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 View Materials /T4290 GoogleMaps • 2 specimens; same collection data as for preceding; RMNH.MOL.340758 GoogleMaps • 13 specimens; same collection data as for preceding; 31.24. 3° S, 28.32. 7°E; NMSA V7178 View Materials /T4291 GoogleMaps • 3 specimens; same collection data as for preceding; NHMUK 20180587 View Materials GoogleMaps .
Other material examined
SHELL ( Fig. 31 View Fig 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 View Fig ). Embryonic shell ( Fig. 28C View Fig ) 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 View Fig ). 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 View Fig ). 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 View Fig ). 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 View Fig ). 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 View Fig ).
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 View Fig 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).
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