Phialodonta perfida, gen. et comb. nov.
Creators: name: Herbert, David G.
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Stylommatophora
Charopidae
Phialodonta
Phialodonta perfida

description: Phialodonta perfida (Burnup, 1912) gen. et comb. nov.
Figs 14, 16 E–H, 19I–J
Trachycystis rotula Melvill & Ponsonby, 1907: 99, pl. 6, figs 12, 12a.
Endodonta [Endodonta (Afrodonta)] perfida Burnup, 1912: 337, pl. 24, figs 1–6. Nom. nov. for Endodonta rotula (Melvill & Ponsonby, 1907), non Hombron & Jacquinot, 1852.
Endodonta (Afrodonta) perfida – Connolly 1912: 128.
Afrodonta perfida – Connolly 1939: 255.
Afrodonta rotula – Solem 1970: 356.
Diagnosis
Shell relatively large, spire distinctly raised, last adult whorl descendant, whorls slightly flat-sided; protoconch evidently smooth (somewhat worn in the material available), diameter ±425 μm; teleoconch sculptured by relatively strong, close-set, compound axial riblets, intervals between riblets with 3–4 microscopic axial threads; spiral sculpture of faint microscopic threads, but for the most part scarcely evident, even in umbilicus; aperture broadly lunate, with no visible dentition; parietal region with a single deeply recessed, low lamella, broadening inwardly; baso-columellar dentition lacking; palatal region with two recessed, relatively long, in-running ridge-like denticles, one at periphery the other in middle of base, visible by transparency; umbilicus wide. Shell translucent, corneous-brown when fresh; diameter up to 1.95 mm.
Material examined
Syntypes (of Trachycystis rotula Melvill & Ponsonby, 1907)
SOUTH AFRICA • 2 specimens (initially registered in error as a single specimen 1907.7.20.45); E. Cape, Grahamstown, Fernkloof; J. Farquhar leg.; following ICZN Art 72.7, these are also syntypes of Endodonta (Afrodonta) perfida Burnup, 1912; NHMUK 1907.7.20.44 to 45.
Additional material (used to re-describe and figure taxon under new name Endodonta (Afrodonta) perfida Burnup, 1912)
SOUTH AFRICA – E. Cape • 1 specimen; Grahamstown, Fernkloof; J. Farquhar leg.; NHMUK 1912.3.25 • 3 specimens; same collection data as for preceding; NHMUK 1937.12.30.2790 to 2792 • 2 specimens; same collection data as for preceding; NMSA A9618/T617 • 3 specimens; Grahamstown; NMSA 2602/T617 • 2 specimens; same collection data as for preceding; NMSA 2603/T617 • 1 specimen; same collection data as for preceding; NMSA A9617/T617.
Other material
SOUTH AFRICA – E. Cape • 3 specimens; Grahamstown, Fernkloof; NMSA V3565 • 6 specimens; same collection data as for preceding; NMSA V3567 • 3 specimens; Grahamstown, Mountain Drive; NMSA V3569.
Distribution and conservation
A narrow-range endemic (Fig. 14), known only from the vicinity of Grahamstown, E. Cape, at ± 700 m a.s.l.; in leaf-litter of southern mistbelt forest. The only material available originates from the Albany Museum, Grahamstown and was collected by J. Farquhar in the early 1900s. Surveying forested habitats in the Grahamstown area should thus be identified as a priority in the hope of finding extant colonies of this species.
Remarks
Burnup (1912) proposed the name perfida on the grounds that the species was referable to Endodonta Albers, 1850 and that the name rotula Melvill & Ponsonby, 1907 was thus a junior secondary homonym of Helix rotula Hombron & Jacquinot, 1852 (non Lowe, 1831, nec Gould, 1851), a species that he also believed to be referable to Endodonta. Although rotula Melvill & Ponsonby, 1907 is not in fact referable to Endodonta, following ICZN Art 59.3, the pre-1961 replacement name remains valid.
Resembles Phialodonta aviana gen. et sp. nov. in that the internal dentition is not visible through the aperture. In that species, however, there are two low, rounded, in-running parietal ridges and three inrunning ridge-like palatal denticles. P. aviana gen. et sp. nov. is also somewhat smaller (diameter up to 1.55 mm). See remarks thereunder.
description: Published as part of 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, pp. 1-55 in European Journal of Taxonomy 629 on pages 46-49, DOI: 10.5852/ejt.2020.629, http://zenodo.org/record/3762280