Aulacospira lens Pall-Gergely & Auffenberg

Pall-Gergely, Barna, Schilthuizen, Menno, Oerstan, Aydin & Auffenberg, Kurt, 2019, A review of Aulacospira Moellendorff, 1890 and Pseudostreptaxis Moellendorff, 1890 in the Philippines (Gastropoda, Pupilloidea, Hypselostomatidae), ZooKeys 842, pp. 67-83 : 71

Aulacospira lens Pall-Gergely & Auffenberg sp. n. Figures 1B, C, 5F

Type material.

Panay Ids., Iloilo Prov., Carles Municipality, ca. 15.0 km E Carles, South Gigante Id., south shore, 75 m, 11°35'N, 123°20.5'E, 24 Apr 1992, K Auffenberg, et al. leg., KA-1039, UF 245485 (holotype, H: 2.0 mm, D: 3.5 mm); same data, UF 525638 (37 paratypes = juvenile/subadult shells); same locality, KA-1040, UF 245505 (7 paratypes = juvenile/subadult shells); same data, 9 paratypes in ethanol.

Diagnosis.

Shell strongly flattened and keeled, all whorls with slight subsutural furrow on the dorsal side, protoconch smooth with slight indication of spiral striation, teleoconch roughly wrinkled without spiral striation; aperture with a columellar and a parietal tooth; aperture adnate to penultimate whorl.

Description.

Shell strongly discoid (1.7-1.9 times as wide as high) with a strong peripheral keel, and a shallow subsutural furrow between the keel and the suture; colour light brownish-greyish with occasionally some purplish colouration; fresh shells with some sand or detritus attached to both dorsal and ventral surfaces, probably functioning as camouflage; shell consists of ca. 4 whorls; protoconch consisting of ca. 1.0 whorl, finely granulose, superficially smooth, with some very faint spiral striation; teleoconch finely granulose, with weak, irregular wrinkles, without spiral striae; aperture strongly oblique to shell axis, aperture shape suboval with palatal elongation due to keel; peristome sharp on the palatal portion above keel, slightly thickened and reflected between keel and columella, and slightly expanded toward umbilicus, partially covering it; parietal callus very weak, often transparent; columellar tooth low on the columella, well-developed, blunt; parietal lamella present only in holotype (all other shells are subadults), relatively long, low, slightly immersed from parietal callus; umbilicus narrow, showing all whorls, partially covered by expanded peristome.

Measurements (in mm).

H = 1.9-2.0, D = 3.5-3.6 (n = 2: the holotype and one large subadult shell).

Differential diagnosis.

Aulacospira lens sp. n. is similar to A. hololoma by the presence of a single columellar tooth, but differs from that species is being larger and much flatter. Aulacospira mucronata is similar to A. lens sp. n. in shape, but it differs from the new species by having a subsutural furrow on the dorsal side of the whorls, a comparatively smaller aperture, a wider umbilicus, and lacking any apertural barriers. Aulacospira triptycha has a larger and flatter, spirally striate shell, a wider umbilicus, has no parietal tooth, but possesses a small palatal denticle.

Distribution.

This species is only known from the type locality on South Gigante Island (Fig. 2). The snails were collected on shaded karst limestone.

Etymology.

The specific epithet lens (Latin lentil) refers to the shape of the new species. It is to be used as a noun in apposition.