Clostophis yoga, Páll-Gergely & Hunyadi, 2022

Páll-Gergely, Barna & Hunyadi, András, 2022, New and little-known species of Clostophis Benson, 1860 from Southeast Asia (Gastropoda: Eupulmonata: Hypselostomatidae), Raffles Bulletin of Zoology 70, pp. 417-439 : 427

Clostophis yoga , new species

( Figs. 10 , 11 )

Type material. Holotype (SH: 1.08 mm, SW: 0.97 mm) ( HNHM 105325 ), Vietnam, Thanh Hóa Province, 23.7 km south of centre of Ng ọc Lặc, Phúc Th ịnh, Làng Mi ềng, rock wall above the village, 65 m a.s.l., 19°55.869′N, 105°22.196′E (locality code: 2020/38), coll. A. Hunyadi, 13 February 2020 . Paratypes: 7 shells, same data as for holotype, coll. HA.

Additional material. 4 juvenile /broken shells, coll. HA, same data as for holotype .

Diagnosis. Clostophis species with a detached last quarter whorl are as follows: C. candidus , new species, C. multiformis Páll-Gergely & A. Reischütz, 2020 , C. proboscideus ( Panha & Burch, 1999) and C. sankeyi . Among them, C. sankeyi is similar to C. yoga , new species, in shell shape, but is much larger, has a wider umbilicus and at least a parietal tooth. The same is true for C. proboscideus , which has an even wider umbilicus than this new species. Clostophis multiformis has a domed dorsal side (shell shape is not concave conical as in this new species), possesses a parietal tooth, and its aperture does not turn towards the umbilicus. Clostophis candidus , new species, is similar to Clostophis yoga in lacking apertural barriers, but it is smaller, has a conical shell, and its aperture does not turn towards the shell axis.

Description. Shell concave conical, shell usually wider than high (as in figured paratype, Fig. 11 ). Whorls slightly, bluntly shouldered. Last ca. quarter whorl detached from penultimate whorl; aperture turns towards spire axis covering edge of umbilicus in ventral view. Therefore, width of body whorl is only slightly wider than that of the penultimate whorl. Protoconch consisting of ca. 1.25 whorls with pronounced spiral striations. Entire shell with 3.75–4 whorls. Umbilicus conspicuously oval, relatively narrow, occupies slightly less than one third of shell width (measured along a horizontal line in Figs. 10E and 11E ). Teleoconch with weak, irregular radial lines and stronger, equidistant spiral striae (18–22 on body whorl in frontal view). Aperture subcircular, toothless, peristome slightly reflected, mostly at its columellar side.

Measurements (in mm). SH = 0.88–1.08, SW = 0.97–1.06 (n = 4).

Etymology. The specific epithet yoga (to be used as a noun in apposition) refers to the aperture that turns toward shell axis, resulting in a distorted shell shape and resembling a yoga position.

Figures

Fig. 10. Clostophis yoga, new species (holotype, HNHM 105325).

Fig. 11. Clostophis yoga, new species (paratype, coll. HA).