Afrodonta mystica, 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 : 15-16

Afrodonta mystica sp. nov.

urn:lsid:zoobank.org:act:95482B02-41BA-4129-A4B1-32DD8DF1D095

Figs 4 G–J, 6, 17M–N

Diagnosis

Shell very small, spire slightly raised; protoconch microscopically shagreened or malleate; teleoconch surface silky; sculpture of simple, close-set, microscopic axial riblets; aperture with a well-developed, crescentic, in-running parietal lamella and a strong baso-columellar denticle; palatal region with a strong, deeply recessed, ridge-like denticle just above mid-whorl, plus a broad, thickened pad below mid-whorl, opposite and below parietal lamella; umbilicus relatively narrow. Shell corneous-brown to yellowish-brown when fresh; diameter up to 1.2 mm.

Etymology

From the Greek mystikos (μυστΙΚός): a mystery, mysterious; with reference to the environs of Nkandla – long considered a region of mystery in Zulu folklore and to this day a place of secrecy, subterfuge and skulduggery.

Material examined

Holotype

SOUTH AFRICA • KwaZulu-Natal, Nkandla Forest ; 28.733° S, 31.133° E; 900 m a.s.l.; 10 Aug. 1997; D.G. Herbert leg.; mistbelt Podocarpus forest, in leaf-litter; diameter 1.16 mm, height 0.61 mm; NMSA V4993/T4237 .

Paratypes

SOUTH AFRICA • 3 specimens; same collection data as for holotype; NMSA P1009/T4238 .

Description

Shell very small, diameter up to 1.2 mm, H/D ratio ±0.53; spire slightly raised; suture indented and apical portion of whorls strongly convex, whorls thus weakly shouldered; periphery more or less at mid-whorl, evenly rounded; last adult whorl slightly descendant. Protoconch comprising apical cap plus approx. 0.75 whorl; diameter ±310 μm; microscopically shagreened or malleate. Teleoconch of up to 2.75 whorls; surface texture silky; sculpture of simple, close-set, microscopic axial riblets; riblets alternating in strength and with even finer spiral threads in their intervals. Umbilicus relatively narrow. Aperture obliquely lunate; parietal region with a well-developed, crescentic, in-running lamella situated well below mid-whorl, extending just beyond edge of aperture, its interior end with a distinct downward deflection; baso-columellar region with a strong denticle (shape somewhat variable); palatal region with a strong, deeply recessed, ridge-like denticle just above mid-whorl, its crest thickened, plus a broad, thickened pad below mid-whorl, opposite and below parietal lamella. Shell corneous-brown to yellowish-brown when fresh.

Distribution and conservation

A narrow-range endemic ( Fig. 6 ), known only from Nkandla Forest, KwaZulu-Natal, at approx. 900 m a.s.l.; living in leaf-litter of transitional mistbelt/scarp forest. This forest is formally protected and under the care of the provincial conservation authority, Ezemvelo KwaZulu-Natal Wildlife.

Remarks

The only other species with a single parietal lamella, Afrodonta bilamellaris and Af. unilamellaris , lack palatal dentition.

Figures

Fig. 4. Shells of Afrodonta species. A–C. Af. inhluzaniensis inhluzaniensis (Burnup, 1912), Balgowan, KwaZulu-Natal, diameter 1.42 mm (NMSA V7240). D–F. Af. inhluzaniensis leptolamellaris subsp. nov., holotype, diameter 1.2 mm (NMSA V7615/T4235). G–J. Af. mystica sp. nov., holotype, diameter 1.16 mm (NMSA V4993/4237). K–N. Af. novemlamellaris (Burnup, 1912), Somerset East, E. Cape, diameter 1.32 mm (NMSA W752).

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.