Glessula tamakoshi Budha & Backeljau

Budha, Prem B., Naggs, Fred & Backeljau, Thierry, 2017, Conchological differentiation and genital anatomy of Nepalese Glessulinae (Gastropoda, Stylommatophora, Subulinidae), with descriptions of six new species, ZooKeys 675, pp. 129-156 : 133

Glessula tamakoshi Budha & Backeljau sp. n. Figs 2C, 5, 13A

Material examined.

Holotype: CDZMTU057P/1, Suridobhan, left bank of Tamakoshi River, Dolakha District, Central Nepal, North face, rocky hill slope, mixed Schima wallichi forest with dominant Lauraceae trees,1023 m, 27.754754N, 86.216755E, 03.II.2009, leg. P.B. Budha. Paratypes: CDZMTU058/13 shells and CDZMTU058P/2 specimens (dissected) from the type locality (same data as holotype).

Distribution.

Only known from the type locality.

Etymology.

The species name refers to the type locality Tamakoshi River valley.

Shell.

Measurements (n = 4): SH 17.7-19.5 mm, SW 9.2-9.6 mm, HA 8.6-8.8 mm, WA 4.9-5.0 mm, Wh 7.0-8.0; holotype: SH 19.5 mm, SW 9.6 mm, HA 8.8 mm, WA 4.9 mm, Wh 7.8. The largest shell measured 19.5 mm, approx. 2 × higher than wide, solid, ovate-conic, light yellowish. Surface glossy, with widely spaced incised radial striations, stronger towards the suture and faint at the middle to lower part of the whorls. The first whorl smooth, blunt with fine and dense striations near the suture. Sides convex, suture fairly impressed. Aperture nearly ovate, 1.7 × higher than wide, peristome simple and thick, columellar margin abruptly truncate, columella slightly curved.

Radula

(Fig. 13A). Teeth pointed, lateral cusps not distinct. Central tooth smaller and with a narrower base than the lateral teeth.

Genitalia

(n = 3) (Fig. 5). Vas deferens with a constant diameter. Flagellum wide comb-like with numerous notches ending in a short hook at the free end. Vagina very short nearly 1/6th length of the penis. Gametolytic sac is oval, connected to the gametolytic duct by a short neck. The penial retractor muscle close to the flagellum. The mass of the hermaphroditic duct highly developed in all dissected samples. Interior of penis with two bulky masses of 'brain-like folds’ (Fig. 5B).

Remarks.

Conchologically, G. tamakoshi sp. n. is similar to South Indian G. indica Gude, 1914 (genitalia unknown) and Sri Lankan G. serena (Benson, 1860). Yet, G. indica has a much wider shell and relatively more whorls (>9 whorls), while the penis of G. serena contains one longitudinal fold and two folds proximal to this longitudinal fold. Schileyko (1999, p. 542, fig. 711) referred the longitudinal fold to as pilaster and the two proximal folds to as the spiral stimulators. In G. tamakoshi sp. n. the interior of the penis contains a bulky masses of brain-like folds (Fig. 5B).