Costulodonta trilamellaris (Melvill & Ponsonby, 1908) gen. et comb. nov.

Figs 11, 12 E–G, 18Q–R

Afrodonta trilamellaris Melvill & Ponsonby, 1908: 134, pl. 7, figs 7, 7a, 7b.

Endodonta [Endodonta (Afrodonta)] trilamellaris – Burnup 1912: 336.

Endodonta (Afrodonta) trilamellaris – Connolly 1912: 128.

Afrodonta trilamellaris – Connolly 1933: text-fig. 1(2); 1939: 252, text-fig. 19(2). — Solem 1970: 357. — Herbert & Kilburn 2004: 250, text-fig.

Diagnosis

Shell very small, spire slightly raised; protoconch with close-set axial riblets (diameter ±415 μm); teleoconch sculpture of compound axial riblets with 2–4 intermediary axial threads; spiral sculpture of close-set, spiral threads, strongest below suture, indistinct elsewhere; parietal region with a low, narrow, in-running ridge; baso-columellar region with a broad, low, in-running ridge; palatal region with a strong, broad, ridge-like denticle just below mid-whorl; umbilicus relatively wide. Shell buff to pale ochre; diameter up to 1.5 mm.

Material examined

Lectotype (by inference, Connolly 1912: 129) SOUTH AFRICA • KwaZulu-Natal, Dargle; H.C. Burnup leg.; NHMUK 1908.12.14.42.

Paralectotypes SOUTH AFRICA • 2 specimens; same collection data as for lectotype; NHMUK 1937.12.30.2793 to 2794 • 4 specimens; same collection data as for lectotype; NMSA 2175/T624 • 3 specimens; same collection data as for lectotype; NMSA 2181/T624 .

Other material

SOUTH AFRICA • 4 specimens; same collection data as for lectotype; ex Albany Museum; NMSA V3552 • 4 specimens; same collection data as for lectotype; ex Transvaal Museum; NMSA W462 .

Distribution and conservation

A narrow-range endemic (Fig. 11), known only from the Dargle area, KwaZulu-Natal, at ± 1150 m a.s.l.; presumably in leaf-litter of southern mistbelt forest. Forested habitats in nature reserves in the Bulwer-Dargle-Karkloof area need to be surveyed in the hope of finding extant colonies of this species in formally protected areas.

Remarks

Despite the KwaZulu-Natal Midlands being a relatively well-sampled area, the original samples collected by Henry Burnup remain the only ones known of this species.