Amatholedonta fordycei, 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 : 24-25

Amatholedonta fordycei gen. et sp. nov.

urn:lsid:zoobank.org:act:750BDD68-09E8-4830-8C54-EE7F0225323F

Figs 8 E–H, 9, 18E–F

Diagnosis

Shell relatively large, biconcave with deep, tightly coiled whorls; spire distinctly sunken; protoconch smooth, globose; teleoconch sculptured by fine, close-set axial riblets, spiral sculpture virtually obsolete; aperture narrow, crescent-shaped, lacking parietal and columellar dentition; palatal region with 1–2 axially aligned rows of denticles set back 1 ⁄ 6 and 1 ⁄ 3 whorl behind outer lip, visible only by transparency; each row with three denticles, situated at, below, and above periphery; umbilicus of moderate width and deep, V-shaped. Shell translucent, straw-brown; diameter up to 2.0 mm.

Etymology

Named after the type locality, Fort Fordyce, E. Cape.

Material examined

Holotype

SOUTH AFRICA • E. Cape, Fort Beaufort area, Fort Fordyce Nature Reserve ; 32.69556° S, 26.48556° E; 1120 m a.s.l.; 30 Dec. 2008; M. and K. Cole leg.; south facing indigenous forest, under logs; diameter 1.84 mm, height 1.10 mm; NMSA W6668/T4270 .

Paratypes

SOUTH AFRICA – E. Cape • 2 specimens; same collection data as for holotype; NMSA P1020/T4271 • 8 specimens; NW of Fort Beaufort, Fort Fordyce Nature Reserve ; 32.667° S, 26.483° E; ± 1100 m a.s.l.; 8 Jul. 2001; C. Symes leg.; in forest leaf-litter; NMSA V9343/T4266 • 11 specimens; Fort Fordyce Nature Reserve , kloof with sheer krantz; 32.68808° S, 26.51304° E; 6 Oct. 2009; M. Cole leg.; ELM D16076/T168 • 20 specimens; Fort Fordyce Nature Reserve, near Harris Hut ; 32.68342° S, 26.47670°E; 5 Oct. 2009; M. Cole leg.; ELM D16087/T169 .

Description

Shell relatively large, diameter up to 2.0 mm, H/D ratio ±0.55, biconcave with deep, tightly coiled whorls; spire distinctly sunken; last adult whorl not descendant; suture strongly indented, and apical and basal portions of whorls strongly convex, peripheral portion evenly rounded. Protoconch comprising globose apical cap plus approx. 1.0 whorl; diameter ±325 μm; smooth. Teleoconch of up to 3.75 whorls; sculptured by fine, close-set axial riblets, with intervals 1.0–1.5 times their width at whorl periphery; spiral sculpture virtually obsolete. Umbilicus of moderate width and deep, V-shaped. Aperture narrow, crescent-shaped, but apical and basal limits rounded; parietal and columellar dentition lacking; palatal region with 1–2 axially aligned rows of denticles set back 1 ⁄ 6 and ⅓ whorl behind outer lip, not visible through aperture and apparent only through translucent shell; each row with three denticles, situated at, below and above periphery, the upper two rounded (uppermost sometimes axially elongate), the lower one an elongate, in-running ridge. Shell translucent, straw-brown.

Distribution and conservation

A narrow-range endemic ( Fig. 9 ), known only from the Fort Fordyce Nature Reserve, near Fort Beaufort, E. Cape, at approx. 1100 m a.s.l.; in leaf-litter of southern mistbelt forest. Fort Fordyce Nature Reserve is a formally protected area managed by Eastern Cape Parks and Tourism Agency.

Remarks

Amatholedonta fordycei gen. et sp. nov. resembles Am. bimunita gen. et comb. nov. from the neighbouring Hogsback region. It differs from that species in having much finer axial sculpture and a somewhat less deeply sunken spire. In addition, the palatal dentition contains only three denticles per row (instead of 5–6), of which the most basal one is markedly more elongate.

Figures

Fig. 8. Shells of Amatholedonta gen. nov. and Biomphalodonta gen. nov. species. A–D. Amatholedonta bimunita (Connolly, 1939) gen. et comb. nov., Hogsback, E. Cape, diameter 2.0 mm (NMSA W6658). E–H. Am. fordycei gen. et sp. nov., holotype, diameter 1.84 mm (NMSA W6668/T4270). I–L. Biomphalodonta forticostata gen. et sp. nov., holotype, diameter 2.13 mm (NMSA V6949/T4261). M–O. B. forticostata gen. et sp. nov., paratype, large specimen, diameter 2.7 mm (NMSA V4886/T4262).

Fig. 9. Distribution of Amatholedonta bimunita (Connolly, 1939) gen. et comb. nov. (green circles), Am. fordycei gen. et sp. nov. (blue circles) and Biomphalodonta forticostata gen. et sp. nov. (orange squares). Contour at 1000 m.