Clostophis platytrochus Páll-Gergely & Hunyadi, 2020

Páll-Gergely, Barna, Hunyadi, András, Grego, Jozef, Reischütz, Alexander, Buczkó, Krisztina & Vermeulen, Jaap J., 2020, Clostophis Benson, 1860, is not a monotypic diplommatinid but a speciose hypselostomatid (Gastropoda: Eupulmonata), with descriptions of six new species, Raffles Bulletin of Zoology 68, pp. 350-368 : 364

Clostophis platytrochus Páll-Gergely & Hunyadi , new species

( Fig. 11 )

Type material. Holotype (SH: 1.00 mm, SW: 1.19 mm) ( HNHM 104408 ), Vietnam, Ðà N ẵng, Ngũ Hành SƠn, Thái SƠn, environment of Chùa Quán Th ế Äm, 7 m a.s.l., 15°59.944′N, 108°15.334′E (locality code: 2019/25a), coll. A. Hunyadi, 11 February 2019 . Paratypes: 18 shells (coll. HA), same data as holotype.

Additional material. 5 juvenile shells, coll. HA, same data as holotype .

Diagnosis. A conical Clostophis species with detached terminal part of body whorl, dense spiral striation on the teleoconch except for largest part of ventral side, and a strongly descending aperture having a strong parietal and a palatal tooth.

Description. Shell white, triangular with flat base. Body whorl bluntly keeled. Terminal part of last whorl detached from penultimate whorl and strongly descending, resulting in a nearly horizontal aperture. Protoconch consisting of 1.25 whorls, with a few (ca. 6) widely-spaced spiral striae. Entire shell with 4.25–4.5 whorls. Dorsal part of teleoconch with irregular, fine radial lines, and stronger spiral striation. Spiral striae on the first whorl of teleoconch of similar density to that on the protoconch, and changes to a denser striation afterwards. Number of spiral striae 12–13 on body whorl above the keel in apertural view. Ventral side of shell with a few spiral striae near the keel, otherwise ornamented by irregular, fine, radial lines only. Umbilicus normally wide, occupies ca. one third of shell width. Aperture strongly oblique to the shell axis, nearly horizontal in lateral view. Peristome expanded but not reflected. Parietal tooth short, elevated, strong, situated in some distance from parietal callus. Palatal tooth blunt but strong, sits nearly on peristome.

Measurements (in mm). SH = 0.96–1.07, SW = 1.12–1.26 (n = 3).

Differential diagnosis. The unique shell shape, especially the slightly keeled body whorl and the sculpture (lack of spiral striae on the largest part of the ventral side) makes this species easy to recognise.

Etymology. The specific epithet is the combination of ‘platus’ (= wide in Greek) and ‘trochus’ (=wheel, Latinised Greek).

Remarks. This new species lives sympatrically with a new Angustopila species (unpublished information) and Tonkinospira danangensis Páll-Gergely & Hunyadi in Páll- Gergely, Grego, Vermeulen, Reischütz, Hunyadi & Jochum, 2019 (see Páll-Gergely et al., 2019).

Figures

Fig. 11. Clostophis platytrochus Páll-Gergely & Hunyadi, new species (HNHM 104408, holotype). A, apertural view; B, lateral view; C, dorsal view; D, ventral view; E, protoconch sculpture; F, G, apertural dentition; H, sculpture of the ventral side; I, sculpture of body whorl from standard apertural view.