Leiostyla paphlagonica subsp. subangulosa Ruud, Menkhorst & Neubert, 2016, subspec. nov.

Leiostyla paphlagonica subangulosa subspec. nov. (Fig. 2)

Type locality & type specimens. – Turkey, Vilayet Amasya, 10.3 km NE. Amasya (in the direction of Yenice/Direkli), 380 m (40.7018°N 35.9608°E), H.P.M.G. Menkhorst leg., 3.viii.1992. Holotype NMBE 544656, paratypes NMBE 544657/11, HMK/>50, RBA/3, RMNH/3, ZMH/3.

Diagnosis. – A subspecies of L. paphlagonica with a basal keel, a small subangularis or, alternatively, a well developed parietal callus between the angular lamella and the palatal insertion of the peristome.

Description. – Shell dextral, elongated oviform in outline with conical spire, with closely arranged, distinctly and rather regularly, oblique striae; there are no spiral striae. The 7.4-7.8 whorls are convex with a deep suture. Shell rather solid, somewhat translucent, dark horn-coloured. The last whorl has a lengthy impression below the palatalis inferior on the outer wall, resulting in a distinct basal keel. Umbilicus open, deep and narrow. Peristome strongly reflected at right angles to form a flat, thickened, whitish lip. There is a marked thickening below the parieto- palatal angle of the peristome. Columellar and palatal insertion of the peristome connected by a clearly visible parietal callus, which slightly thickens near its ends. Angular lamella prominent, high, without appendages; it does not reach the border of the parietal callus. The angular lamella is fused with the palatal insertion of the peristome by a well developed callus; alternatively, a small subangular thickening is present that fuses on one side with the palatal insertion and on the other side with the angular lamella. Parietalis rather weak, deep inside the aperture; it is not connected with the angular lamella. Palatalis inferior very long and well developed; it does not reach the lip. The columellaris is horizontally projected at or above the middle of the columellar side of the aperture.

Measurements (n = 6). – H = 3.6-4.0 (mean 3.8); LWH = 1.8-1.9 (mean 1.9); MH = 1.2-1.4 (mean 1.3); LWD = 1.7-1.8 (mean 1.8); LWM = 1.8-1.9 (mean 1.8); MD = 1.1-1.2 (mean 1.1); NW = 7.4-7.8 (mean 7.6).

Localities. – Known from the locus typicus only (see above).

Derivatio nominis. – Named after the presence of the subangularis, which is missing in L. paphlagonica incisa Hausdorf, 1990.

Differentiation. – Leiostyla p. subangulosa differs from L. p. paphlagonica (Fig. 1) by the presence of a spiral furrow on the outer wall of the last whorl; this furrow is located below the palatalis inferior. Furthermore, the parietal callus is clearly less thickened, and the angular lamella and parietalis are more weakly developed. In addition, the radial striae are less regular and less densely packed. Leiostyla p. subangulosa differs from L. p. incisa by the presence of a subangularis or, alternatively, the more prominently developed parietal callus (which fuses the angular lamella to the palatal insertion of the peristome) and the less diffuse palatalis inferior.

Remarks. – So far only three populations have been recorded for L. paphlagonica, each population having its own subspecific status (paphlagonica: Vilayet Kastamonu, Kapısuyu, incisa: Vilayet Kastamonu, Azdavay; subangulosa: Vilayet Amasya, Amasya). Much more field work has to be carried out to delineate the precise distribution area and subspecies boundaries of this polytypic species.