Bythinella wilkei Yildirim , Kebapci & Bahadir Koca

Yildirim, Mehmet Zeki, Kebapci, Uemit, Koca, Seval Bahadir & Yuece, Arzu, 2015, New Bythinella (Gastropoda, Bythinellidae) species from western Turkey, ZooKeys 481, pp. 1-13 : 6-9

Taxon classification Animalia Littorinimorpha Bythinellidae

Bythinella wilkei Yildirim, Kebapci & Bahadir Koca sp. n. Figs 5, 6d

Holotype

(Coll. Yıldırım): SH 2.75 mm, SW 1.84 mm, ah 1.28 mm, aw 1.12 mm; TURKEY, Kocaeli, Maşukiye, spring along the road to Kartepe, 40°40.603'N, 30°08.605'E, leg. S. Bahadır Koca. Paratypes: 29 ex in Coll. Yıldırım, same data and locality as holotype.

Type locality.

Spring along the road to Kartepe, Maşukiye, Kocaeli.

Etymology.

Named after the malacologist Thomas Wilke (Justus Liebig University, Germany).

Description.

Shell oval conical, light brown, but appearing blackish due to encrustation; having 3-3.5 tumid whorls; last whorl slowly increasing and broader than previous whorls, sutures deep. Apex blunt. Aperture roundish oval, last whorl strongly descending towards aperture and aperture projected forward, lip in some individuals having a small protuberance in upper palatal margin. Umbilicus small, hollow or completely covered by the lip. Operculum ovate, translucent and with distinct growth lines.

Head having little pigmentation, pigment rather concentrated on bases of the tentacles and around mouth. Tentacles short and broad. Unpigmented penis tapering towards the tip, tip not pointed at its distal end; tubular gland thick and with two convolutions. Bursa copulatrix narrow and elongated, rs1 elongate. Central tooth of radula with 9 pointed cusps, 1 median and 4 each on sides; lateral margins lacking cusps, but undulated.

Measurements (n=22): SH: 2.80 mm (min 2.56/max 3.03), SW: 1.88 mm (min 1.56/max 2.19), SH/SW: 1.50 (min 1.31/max 1.68), SW/SH: 0.66 (min 0.60/max 0.76), ah/SH: 0.47 (min 0.41/max 0.51).

Differential diagnosis.

Excluding Bythinella anatolica sp. n. described from Manisa Province, Bythinella wilkei sp. n. has a larger shell than other Turkish congeners. The nearly circular aperture, which is strongly descending and projected forward, is also characteristic of the new species.

Habitat.

The specimens were collected from the outflow of a small spring having little vegetation and a gravel substrate.

Remarks.

The species is one of the two northernmost distributed congeners in Turkey. Unlike Bythinella istanbulensis sp. n. the new species is found in higher altitudes.