Pseudavakubia ghanaensis de Winter, 2013

de Winter, A. J. & Vastenhout, N., 2013, Revision of the Afrotropical land snail genus Avakubia Pilsbry, 1919, with description of Pseudavakubia gen. n. and eleven new species (Gastropoda: Pulmonata: Streptaxidae), African Invertebrates 54 (2), pp. 605-663 : 654-656

Pseudavakubia ghanaensis de Winter , sp. n.

Fig. 30

Etymology: The species name refers to the country of origin.

Diagnosis: Differs from the similarly sized P. atewanensis by the less elongate shell with lower protoconch; peristome proportionally larger and less rounded, with the palatal lip curved in lateral view. The shell of P. liberiana is smaller and has less strong apertural dentition. P. majus has a much larger shell.

Description:

Shell ( Fig. 30): Small (H 3.3–3.4 mm, holotype 3.3 mm), ovoid-subcylindrical, moderately high-spired, H:D 1.62–1.75, in holotype 1.74, greatest diameter at penultimate whorl. Whorls above widest portion of shell moderately tapering. Whorls 6½–7, moderately convex, whorl increase slow, coiling tightness ca 5.4–5.8, in holotype 5.8. Protoconch diameter 1.04–1.15 mm, of holotype 1.12 mm. Protoconch irregularly coiled with greatly varying whorl width, apex appearing less acuminate than in P. atewanensis. Protoconchs of all shells more or less eroded, obscuring fine details. First 1¼ whorl without prominent sculpture, later protoconch (ca ¾ whorl) with five distant spiral ridges. Transition of smooth to spirally sculptured portion of protoconch abrupt, transition from protoconch to axially ribbed teleoconch somewhat gradual, first 3–4 axial ribs of teleoconch being crossed by spiral cords of protoconch. BWH 41–44% of shell height, in holotype 41%. Periphery of body whorl more or less rounded. Peristome entire, not strongly incrassate, squarish in outline, higher than wide; PH:PW 1.03–1.12, in holotype 1.07, PH 32–36 % of H, in holotype 33%, PW 52–55 % of D, in holotype 54 %. Apertural lip rather wide and flaring. Palatal­basal lip in lateral view curved, arching forward. Angular tooth somewhat protruding, continuing as deeply entering lamella. Tooth on mid-palatal wall strong and pointed. Umbilicus fully closed, umbilical depression with radiating ribs. Teleoconch sculpture consists of slightly oblique, somewhat curved axial ribs, 6.5–9.4 ribs/mm, with fine spirals in interstices.

Body colour: Dried-in soft parts of holotype at least partly red.

Anatomy: Unknown.

Holotype: GHANA: Western Region : Ankasa Conservation area, 5.25411°N 2.64037°W, 60 m, 15.i.2010, M.E. Nutsuakor, P. Tattersfield & A.J. de Winter, wet evergreen forest ( RMNH.MOL.122857).

Other material examined: GHANA: Central Region: 2 ad. dry shells, Pra Suhien Forest Reserve , 5.34807°N 1.39002°W, 230 m, 10.vi.2008, M.E. Nutsuakor & A.J. de Winter, moist evergreen forest ( RMNH.MOL. 330215–330216) ; 1 ad. dry shell, Kakum National Park , 5.3558°N 1.3925°W, 220 m, moist evergreen forest along stream, 6.vi.2008, M.E. Nutsuakor & A.J. de Winter ( RMNH.MOL.330217) .

Distribution ( Fig. 31): So far known from south-central and south-western Ghana.

Habitat:All material was collected from leaf­litter on the floor of old secondary lowland (wet and moist) evergreen forest.

Remarks: In P. ghanaensis we provisionally lodge the scanty material (four adult shells, one of which severely damaged) from three localities in central and western Ghana. These shells differ from those of P. atewanensis and P. liberiana by a comparatively less irregularly coiled protoconch (resulting in a flatter apex which seems less conspicuous distorted in lateral views), a higher than wide peristome, and by a distinctly curved, forward arching palatal lip (in lateral view). In view of the variation in these shells it seems possible that more than one species is involved, and additional material from more localities is needed to assess the variability.