Pseudavakubia majus de Winter & Vastenhout, 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 : 649-651

Pseudavakubia majus de Winter & Vastenhout , sp. n.

Figs 26, 27

Etymology: From Latin majus (larger), in reference to the comparatively large shell of this species.

Diagnosis: A comparatively large, cylindrical species of Pseudavakubia .

Description:

Shell ( Fig. 26): Large, H 4.3 (holotype) – 4.4 mm, cylindrical-biconical, largest width at penultimate whorl, high-spired, H:D 1.94–1.95. Whorls 7¼, little convex, whorl increase fast, coiling tightness 4.9–5 (holotype). Protoconch diameter 1.4 (holotype) – 1.6 mm. Protoconch irregularly coiled, whorl diameter increase of first whorls uneven. First 1½ protoconch whorl almost smooth (not studied with SEM), shining. Remaining ¾ protoconch whorl with 5–6 low, irregularly spaced cords. Boundary between smooth and spirally sculptured portion of protoconch sharp; transition from protoconch to teleoconch more gradual with a short zone of reticulate sculpture of axial ribs crossed by spirals. Body whorl proportionally large, BWH 42–44% of H, in holotype 42%. Periphery of last whorl rounded. Peristome entire, not strongly incrassate, higher than wide, PH:PW 1.06–1.14, in holotype 1.14. PH 33–34 % of H, in holotype 33 %, PW 57–62% of D, in holotype 57%. Palatal-basal lip in lateral view curved and arching forward. Tooth on mid-palatal wall blunt.Angular tooth protrudes, proceeding inwards as low, deeply entering lamella. Umbilicus closed, umbilical depression with radiating ribs. Teleoconch sculptured by slightly oblique, regularly spaced axial ribs, 9.2–10.7 ribs/mm, in holotype 9.2, with fine spirals in interstices.

Body colour: Ommatophores of preserved specimen bright orange, other soft parts without obvious colouration.

Anatomy ( Fig. 27): See genus diagnosis.

Holotype: GHANA: Eastern Region : Atewa Range Forest Reserve, 6.24558°N 0.54654°W, 660 m, steep, East­facing slope in upland evergreen forest, 22.i.2010, M.E. Nutsuakor, P. Tattersfield & A.J. de Winter ( RMNH.MOL.123136).

Paratype: 1 specimen, shell fragments, soft parts dissected, same data as holotype ( RMNH.MOL.123323) . Other material examined: GHANA: Eastern Region: 1 ad. dry shell, Atewa Range Forest Reserve, plateau in upland evergreen forest, 6.23204°N 0.57471°W, 735 m, 22.i.2010, M.E. Nutsuakor, P. Tattersfield & A.J. de Winter ( RMNH.MOL.125937) .

Distribution ( Fig. 31): Only known from the Atewa Range Forest Reserve in Ghana.

Habitat: Two live specimens were collected from the understorey vegetation in upland evergreen forest at 660– 735 m. Found sympatrically with P. atewaensis .

Remarks: One adult shell with a clearly shorter spire ( Figs 26F, G) may have prematurely reached adulthood (shell with developed aperture with barriers and reflected lip), as is suggested by the smaller shell height, smaller number of whorls and less tightly closed umbilicus. Measurements of this specimen are not included in the above description as the specimen may be atypical for the species.