Costulodonta trilamellaris ( Melvill & Ponsonby, 1908 ) Herbert, 2020

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 : 34-35

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.

Figures

Fig. 11. Distribution of Costulodonta gen. nov. species. C. acinaces (Connolly, 1933) gen. et comb. nov. (green square), C. bidens gen. et sp. nov. (turquoise squares), C. burnupi (Connolly, 1933) gen. et comb. nov. (orange square) C. pluridens gen. et sp. nov. (pink squares), C. trilamellaris (Melvill & Ponsonby, 1908) gen. et comb. nov. (royal blue square). Contour at 1000 m.

Fig. 12. Shells of Costulodonta gen. nov. species. A–D. C. pluridens gen. et sp. nov., holotype, diameter 1.8 mm (NMSA V5920/T4267). E–G. C. trilamellaris (Melvill & Ponsonby, 1908) gen. et comb. nov., paralectotype, Dargle, KwaZulu-Natal, diameter 1.45 mm (NMSA 2181/T624).