Afrodonta unilamellaris Connolly, 1933

Herbert, David G., 2020, Revision of the aperturally dentate Charopidae (Gastropoda: Stylommatophora) of southern Africa - genus Afrodonta s. lat., with description of five new genera, twelve new species and one new subspecies, European Journal of Taxonomy 629, pp. 1-55 : 19-20

Afrodonta unilamellaris Connolly, 1933

Figs 6 , 7 E–G, 18A–B

Afrodonta unilamellaris Connolly, 1933: 146 , text-fig. 1(6), pl. 7, figs 2–4. Afrodonta unilamellaris – Connolly 1939: 250, text-fig. 19(6). — Solem 1970: 360. — Herbert & Kilburn 2004: 248, text-fig.

Diagnosis

Shell small, spire weakly raised, whorls somewhat flat-sided; protoconch smooth, at most microscopically shagreened (diameter ±375 μm); teleoconch texture silky; sculpture comprising simple, very fine and close-set axial riblets of alternating strength; spiral sculpture of fine indistinct threads in riblet intervals; parietal region with a single rounded in-running ridge-like lamella (occasionally the crest divided by a groove); baso-columellar and palatal regions lacking dentition; umbilicus relatively narrow. Shell buff to pale ochre when fresh; diameter up to 1.6 mm.

Material examined

Holotype

SOUTH AFRICA • KwaZulu-Natal, Mfongosi; W.E. Jones leg.; NHMUK 1931.6.4.3.

Paratypes

SOUTH AFRICA • 6 specimens; same collection data as for holotype; NHMUK 1937.12.30.2795 to 2800 .

Other material

SOUTH AFRICA – KwaZulu-Natal • 5 specimens; KwaZulu-Natal, Mfongosi; 28.713° S, 30.805° E; W.E. Jones leg.; NMSA A9186 • 1 specimen; same collection data as for preceding; NMSA A9194 • 16 specimens; same collection data as for preceding; NMSA A9195 .

Distribution and conservation

A narrow-range endemic ( Fig. 6 ), known only from the Mfongosi area (± 500 m a.s.l.) in the Thukela River valley below Kranskop, KwaZulu-Natal; no accurate habitat data available. This area is not afforded any formal protection and is threatened by impacts related to subsistence agriculture.

Remarks

Unlikely to be confused with any other species. The original samples collected by W.E. [‘Mamba’] Jones remain the only ones known. The Mfongosi area contains a number of small, isolated limestone bodies belonging to the Ntingwe Group ( Martini 1987) from which other narrow-range endemic land snails are known, e.g., Anisoloma falconiana (Pilsbry, 1929) and Gulella leucocion Connolly, 1929 . Herbert & Kilburn (2004: 53) discussed the interesting history of this locality and the original collector.

Figures

Fig. 6. Distribution of narrow-range Afrodonta species. Af. geminodonta sp. nov. (purple triangles), Af. mystica sp. nov. (orange square), Af. pentodon sp. nov. (green circles) and Af. unilamellaris Connolly, 1933 (blue circle). Contour at 1000 m.

Fig. 7. Shells of Afrodonta species. A–D. Afrodonta pentodon sp. nov., holotype, diameter 1.45 mm (NMSA V6950/T4239). E–G. Afrodonta unilamellaris Connolly, 1933, Mfongosi, KwaZulu-Natal, diameter 1.52 mm (NMSA A9186).