Revision of the Afrotropical land snail genus Avakubia Pilsbry, 1919, with description of Pseudavakubia gen. n. and eleven new species (Gastropoda: Pulmonata: Streptaxidae) de Winter, A. J. Vastenhout, N. African Invertebrates 2013 2013-12-31 54 2 605 663 7Q9GV de Winter de Winter & Vastenhout 2013 [398,779,709,735] Gastropoda Streptaxidae Avakubia Animalia Stylommatophora 30 635 Mollusca species occidentalis sp. nov.   Figs 16, 21C, D Etymology: From Latin  occidentalis(western), in reference to the westernmost distribution of this species among any known  Avakubiaspecies. Diagnosis: A small species of  Avakubia, differing from similar-sized congenerics by a combination of conchometrical characters, as well as by the large number of spiral cords on the protoconch. Description:  Shell( Figs 16, 21C, D, Table 1): Small to medium-sized (mean H 3.3 mm), subcylindrical, largest width at penultimate whorl. H:D 1.59–1.84, in holotype1.84. Number of whorls 5–5.5. Coiling tightness 4.45–4.65, in holotype4.45. Whorls moderately convex. Protoconch slightly acuminate, consisting of ca2 whorls. Protoconch on second whorl with>16, more or less regularly spaced cords, 6.3–8.6 µm wide, without finer spiral lines between them. Spiral cords made up of series of adjoining, poorly differentiated rectangular particles of variable length ( ca8–19 µm). Teleoconch sculpture of regularly spaced, curved axial ribs, 9.0–10.0 ribs/mm on penultimate whorl, median 9.9 ribs/mm, in holotype9.0, with fine spirals in interstices. BWH 48–49 % of H, in holotype48%. Peristome holotypeentire (peristome of other shells damaged, PW measurements not accurate). PH:PW 0.88–1.10, in holotype1.06. PH32–34 % of H, median 34 %, in holotype34 %. PW 52–59% of D, median 56%, in holotype59%. Apertural lip expanded and flaring, reflected and incrassate in holotype. Two barriers visible in aperture: a blunt, tooth-like thickening on mid-palatal wall and a conspicuous angular tooth that extends inwards as deeply entering lamella. Internal wall of body whorl with deeply-set palatal fold, externally barely visible in opaque shells. Columellar lamella not visible in aperture, but probably present. Umbilicus punctiform but open, slightly wider than in  A. fruticicola.  Body colour: Soft parts at least partly reddish (dried-in tissue paratype).  Anatomy: Unknown.   Holotype: GHANA:  Volta Region: Logba Tota, 6.88363°N 0.46804°E,  470 m,  30.i.2010, P. Tattersfield, M.E. Nutsuakor& A.J. de Winter, semi­deciduous forest on steep slope near waterfall ( NMW.Z. 2013.055.00001).   Paratype: 1 dry shell, same data as holotype ( RMNH.Mol.254654). Other material examined:  GHANA:  Eastern Region: 1 dry shell, Atewa Range Forest Reserve, 6.12368°N 0.60445°W,  655 m,  23.i.2010, P. Tattersfield, M.E. Nutsuakor& A.J. de Winter, in litter of recently logged high forest ( RMNH.MOL.330190). Distribution ( Fig. 17): Known from two localities in eastern Ghana. Habitat: Found in semi-deciduous forest near waterfall at 470 m, as well as in upland evergreen forest at  650 m.All specimens were collected from the forest floor. Remarks: This species superficially resembles  A. fruticicolain size, teleoconch sculpture and colour of the soft parts. However, the Ghanaian shells differ in a number of characters, such as a more cylindrical shell, tighter coiled whorls (about half a whorl more at the same size), proportionally smaller body whorl, more pointed apex, and slightly wider umbilicus and wider spaced axial ribs, in addition to details of the protoconch sculpture. Two  A. occidentalisspecimens were found alive on the forest floor, whilst specimens of  A. fruticicolawere exclusively collected from the understorey vegetation.The Ghanaian localities are situated some 1200 kmfrom those of  A. fruticicolain Cameroon.  Fig. 16.  Avakubia occidentalis sp. n., holotype, NMW.Z.2013.055.00001, apertural (A), lateral (B, C), umbilical (D) and apical (E) views. Scale bar = 1 mm.  Fig. 17. Distribution records of  Avakubia occidentalis sp. n.   Avakubia occidentalisis the only  Avakubiaspeciesknown in the Upper Guineaforest block. Traditionally postulated biogeographic barriers like the DahomeyGap and Cross River have apparently not restricted the distribution of the genus, which might suggest a considerable age for the taxon. On molecular grounds Rowson et al. (2011)suggested  Avakubiato be an ancient taxon that possibly survived the Mesozoic ⁄ Cainozoic mass extinctions, whilst the streptaxid diversity is otherwise known from the Cainozoic only. 2010-01-30 NMW P. Tattersfield & M. E. Nutsuakor & A. J. de Winter Ghana 470 6.88363 Logba Tota 1 0.46804 31 636 1 Volta holotype [181,788,289,311] 2010-01-30 RMNH P. Tattersfield & M. E. Nutsuakor & A. J. de Winter Ghana 470 6.88363 Logba Tota 1 0.46804 31 636 1 Volta paratype 2010-01-23 RMNH P. Tattersfield & M. E. Nutsuakor & A. J. de Winter Ghana 655 6.12368 Eastern Region 1 -0.60445 Atewa Range Forest Reserve 31 636 1