Haploptychius von Moellendorff , 1906

Sian Man, Nem, Siriboon, Thanit, Lin, Aung, Sutcharit, Chirasak & Panha, Somsak, 2022, Revision of the carnivorous land snail family Streptaxidae (Stylommatophora, Achatinina) in Myanmar, with description of four new species, ZooKeys 1110, pp. 39-102 : 39

Genus Haploptychius von Moellendorff, 1906

Haploptychius von Möllendorff in Kobelt, 1906: 127. Zilch 1960: 562. Richardson 1988: 211. Schileyko 2000: 796, 797. Inkhavilay et al. 2016: 26, 27. Do et al. 2015: 40. Bui et al. 2019: 90.

Odontartemon (Haploptychius) - Thiele 1931: 730. Forcart 1946: 215.

Oophana (Haploptychius) - van Benthem Jutting 1954: 76, 95.

Type species.

Streptaxis sinensis Gould, 1859, by original designation.

Diagnosis.

Shell oblique-heliciform to ovate and last whorl deflected. Penultimate whorl round to bluntly angular and extended beyond last whorl. Apertural dentition includes only one parietal lamella. Genitalia with penial sheath thin to thick and extending ~ 1/2 to entire penis length. Penial hooks dense, slightly expanded at base, tips pointed, located on low to high conical papillae and vaginal hooks absent.

Remarks.

Haploptychius is almost identical with Carinartemis in having a deflected last whorl, extended penultimate whorl, and bearing a single parietal lamella. However, Haploptychius can be recognized by its oblique-ovate shell and rounded to angular penultimate whorl, while Carinartemis possesses an oblique-heliciform shell with sharply keeled penultimate whorl. In genitalia, Haploptychius has long and slender penial hooks, without vaginal hooks, while Carinartemis possesses shorter and blunt penial hooks, and sometimes transparent vaginal hooks may be present ( Siriboon et al. 2014b; Inkhavilay et al. 2016).

A recent molecular phylogeny revealed that Haploptychius is polyphyletic, and the traditional genus concept using shell shape and apertural dentition seems unreliable ( Siriboon et al. 2020). However, further intensive genital examination and molecular analysis of the type species are necessary to restrict the Haploptychius s.s., and generic revision absolutely requires both forms of evidence. Therefore, since the morphological and molecular evidence have never been evaluated, we follow the traditional genus concept in recognizing the streptaxids with oblique-heliciform shells and only one parietal lamella as members of the genus Haploptychius s.l.

Currently, the genus Haploptychius is comprised of about 40 nominal species distributed from India to Indochina, southern and central China, and Sulawesi of Indonesia ( Kobelt 1906; Blanford and Godwin-Austen 1908; Zilch 1961; Richardson 1988; Schileyko 2000; Do and Do 2015; Inkhavilay et al. 2016). In addition, five species of Haploptychius s.l. have been documented mainly in southeastern Myanmar ( Blanford and Godwin-Austen 1908), and three new species are added in this study.