Clostophis Benson, 1860

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 : 351-352

Clostophis Benson, 1860

Clostophis Benson, 1860: 95 .

Montapiculus Panha & Burch, 1999a: 148 . (new synonym) Montapiculus — Panha & Burch, 2005: 38, 109.

Type species. Clostophis sankeyi Benson, 1860 , by monotypy.

Grammatical gender. Masculine.

Diagnosis. Shell minute, colourless (white), body whorl rounded or very slightly keeled or shouldered, detached from penultimate whorl forming a free tube, or normally attached to penultimate whorl; shell surface finely reticulated caused by the radial growth lines and stronger, dense spiral lines (usually at least 20 striae on the body whorl, counted from apertural view); aperture toothless, or with a short but often high parietal tooth, in some species with a palatal tooth.

Differential diagnosis. Angustopila shells are smaller, the body whorl is never detached from the penultimate whorl, and the spiral striation is less dense (up to 20 striae on the body whorl, counted from apertural view). Species assigned to Tonkinospira are mostly colourless and possess dense spiral striation, similar to Clostophis , but the aperture is toothless and the peristome is often not reflected. It is possible that Clostophis and Tonkinospira are not mutually monophyletic. Acinolaemus species have more apertural barriers, and at least the type species possesses a parietal and a separate angular tooth. Species assigned to Acinolaemus also need a generic revision. Hypselostoma (at least its type species) is large (ca. 4 mm), has reduced spiral striation, and is brown in colour, not colourless like Clostophis . See also Discussion.

Included species. The genus Clostophis currently comprises ten species: C. incurvus Páll-Gergely & Vermeulen , new species; C. infantilis Páll-Gergely , new species; C. koilobasis Páll-Gergely & Vermeulen , new species; C. multiformis Páll-Gergely & A. Reischütz , new species; C. neglectus (van Benthem Jutting, 1961) ; C. obtusus Páll-Gergely & Grego , new species; C. proboscideus ( Panha & Burch, 1999a) ; C. platytrochus Páll-Gergely & Hunyadi , new species; C. sankeyi Benson, 1860 ; and C. stochi (Páll-Gergely & Jochum in Páll-Gergely, Jochum & Asami, 2017) ( Fig. 1 ).

Remarks. Clostophis was considered a diplommatinid genus ( Benson, 1860; Kobelt, 1902; Egorov, 2013) although Benson (1860) had already mentioned that it might be related to Hypselostoma . After examining the holotype of Clostophis sankeyi , it became evident that the minute, white, finely reticulate shell with a descending aperture and the single parietal tooth is characteristic for the monotypic genus Montapiculus Panha & Burch, 1999 (type species: Montapiculus proboscidea Panha & Burch, 1999 , by original designation). Thus, Montapiculus is a junior synonym of Clostophis . The two species, due to the considerable differences between them, are considered valid. The type locality of C. proboscideus is situated ca. 240 km in a straight line from that of C. sankeyi ( Fig. 2 ).

Some additional species, for example Hypselostoma edentata (Panha & Burch, 1999) , might also belong to Clostophis and will need to be confirmed by further study.

Figures

Fig. 1. Synoptic view of Clostophis species. A, Clostophis sankeyi (UMZCI.103320, holotype, copyright: The Trustees of the Natural History Museum, photo: Harry Taylor); B, Clostophis stochi (MZUF GC/49405, holotype, from the original description: Páll-Gergely & Jochum in Páll-Gergely et al., 2017); C, Clostophis infantilis, new species (MNHN-IM-2014-6401, holotype); D, Clostophis incurvus, new species (NHMUK 20191125, holotype); E, Clostophis platytrochus, new species (HNHM 104408, holotype); F, Clostophis multiformis, new species (NHMW 113273, holotype); G, Clostophis obtusus, new species (HNHM 104435, holotype); H, Clostophis koilobasis, new species (NHMUK 20191126, holotype); I, Clostophis neglectus (drawing from the original description: van Benthem Jutting, 1961); J, Clostophis proboscideus (holotype from the original description). Scale = 1 mm.

Fig. 2. Known distribution of Clostophis species. Empty triangle: Clostophis stochi; inverted empty triangle: C. proboscideus; filled triangle: Clostophis sankeyi; inverted filled triangle: Clostophis koilobasis, new species, and Clostophis incurvus, new species; filled square: Clostophis neglectus; filled diamond: Clostophis platytrochus, new species. Inset map shows the distribution of Clostophis multiformis, new species (circles with labels, see explanation in the text), Clostophis obtusus, new species (empty diamond), and Clostophis infantilis, new species (empty square), east of Thakhek.