Genus Phialodonta gen. nov.

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Type species

Phialodonta aviana gen. et sp. nov.

Diagnosis

Shell very small to relatively large (adult diameter ± 1.3–2.0 mm), spire slightly sunken to slightly elevated; umbilicus moderate to very wide; whorls strongly rounded, periphery at mid-whorl. Protoconch smooth or with low, weakly undulant axial sculpture. Teleoconch with close-set axial riblets; riblets compound, composed of several periostracal lamellae; intervals between riblets with several finer intermediary axial threads; spiral sculpture weak, at most comprising extremely fine, close-set spiral threads. Aperture lunate to broadly lunate, variously furnished with parietal and palatal dentition in the form of denticles and/or in-running lamellae/ridges.

Etymology

From the Latin phiala: a saucer or bowl, and donta: a contraction of Afrodonta; with reference to the wide, shallow umbilicus. Gender feminine.

Remarks

Phialodonta gen. nov. is proposed for a group of species which share a smooth or weakly sculptured protoconch and a relatively coarse teleoconch sculpture of compound axial riblets with multiple fine intermediary axial threads. The genus ranges widely, from the Agulhas region, W. Cape to the KwaZulu-Natal Midlands. In Costulodonta gen. nov. the protoconch has distinct radial riblets and the teleoconch sculpture is generally somewhat finer. Members of Afrodonta have a somewhat similar protoconch, but they possess a silky teleoconch sculpture comprised of simple axial riblets of alternating strength.