Costulodonta, 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 : 27

Genus Costulodonta gen. nov.

urn:lsid:zoobank.org:act:FC341D9C-2CC1-4B4C-8E9B-629F7913DD46

Type species

Afrodonta acinaces Connolly, 1933 .

Diagnosis

Shell small (max. diameter ± 1.8 mm), spire flat or weakly raised; umbilicus moderate to wide; whorls tightly coiled, strongly rounded apically and basally, less so at periphery; last adult whorl weakly descendant. Protoconch with fine, close-set, regularly spaced axial riblets; riblets crisp and simple, often with indistinct traces of irregular spiral threads in their intervals. Teleoconch also with fine, closeset axial riblets, but these coarser than those on protoconch; riblets compound, composed of several periostracal lamellae; intervals between riblets with finer intermediary axial threads; spiral sculpture absent or restricted to microscopic spiral threads. Aperture obliquely lunate, slightly wider basally; aperture variously furnished with parietal and palatal dentition in the form of denticles and/or in-running lamellae/ridges.

Etymology

From the Latin costa: a rib, diminutive costula, and donta: a contraction of Afrodonta ; with reference to the axial sculpture of the protoconch. Gender feminine.

Remarks

Costulodonta gen. nov. is proposed for a group of species which share a costate protoconch and relatively coarse teleoconch sculpture of compound axial riblets with multiple fine intermediary axial threads. The genus is known only from the afrotemperate and mistbelt forests of the KwaZulu-Natal interior. Members of Afrodonta differ from Costulodonta gen. nov. in having a smooth protoconch and a silky teleoconch sculpture comprising simple axial riblets of alternating strength.