Clostophis Benson, 1860

Tongkerd, Piyoros, Janjai, Teerangkul, Pholyotha, Arthit, Gojšina, Vukašin, Panha, Somsak & Sutcharit, Chirasak, 2025, The microsnail genera Clostophis and Acinolaemus (Eupulmonata, Pupilloidea, Hypselostomatidae) from central Thailand, with description of three new species, ZooKeys 1258, pp. 35-71 : 35-71

Clostophis Benson, 1860

Clostophis Benson, 1860: 95. Kobelt 1902: 484. Thiele 1929: 111. Páll-Gergely et al. 2020: 351, 352. Páll-Gergely and Hunyadi 2022: 419. Preece et al. 2022: 145, 256.

Montapiculus Panha & Burch, 2002: 148. Type species: Montapiculus proboscidea Panha & Burch, 2002. Panha and Burch 2005: 38, 109.

Type species.

Clostophis sankeyi Benson, 1860 , by monotypy.

Remarks.

The genus was recently revised by Páll-Gergely et al. (2020) and Páll-Gergely and Hunyadi (2022), who recorded two species from southeastern Myanmar, six species from Laos, six species from Vietnam, two species from Peninsular Malaysia, and two species from Thailand. All these species share strong spiral ridges, usually with one or many apertural dentitions (except for four species with no dentition), and a more or less detached last whorl (tuba). Other characters, such as shell shape and tuba length, show large intraspecific variation (although they can be useful in some cases to distinguish species). Based on its wide distribution and its substantial morphological variability, the genus can be divided into three phenotypic species groups:

Clostophis sankeyi species group: with 0–4 apertural dentitions, a long (~ 1 / 4 whorl or more) and descending tuba, and a conical shell shape with strongly concave sides. This group consists of five species (including Clostophis rhynchotes sp. nov.) distributed in Myanmar, Thailand, and northern Vietnam (Fig. 2 A , Table 3 ).

Clostophis charybdis species group: with 0–2 apertural dentitions, no to short tuba, moderately to strongly conical shell, concave sides, and aperture opened laterally to sublaterally. This species group comprises ten species, of which nine species are distributed mainly in the central to northern Annamite Ranges in Laos and central to northern Vietnam; one species is found in southern Myanmar (Fig. 2 A , Table 3 ).

Clostophis bactrianus species group: with four or five strong apertural dentitions, absent to short tuba, and conical to slightly concave sides. This group consists of five species with disjunct distributions. Three species from southern China tend to have long denticles deeper inside the aperture, whereas the two species from Peninsular Malaysia tend to have short denticles situated near the apertural lip (Fig. 2 A , Table 3 ).

Figures

Figure 2. Approximate type localities. A. All Clostophis species. Colours indicate different species groups; numbers correspond to the species listed in Table 3; B. All Acinolaemus species; numbers correspond to the species listed in Table 4.