Haploptychius tenasserimicus Man & Panha, 2022

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

Haploptychius tenasserimicus Man & Panha sp. nov.

Fig. 13A-C

Type material.

Holotype CUMZ 13011 (Fig. 13A ). Measurements: shell height 4.5 mm, shell width 8.6 mm, and 6 whorls. Paratypes CUMZ 13012 (5 shells; Fig. 13B, C ), NHMUK (2 shells).

Type locality.

This new species was found from the limestone karsts near Lampane Village, Tanintharyi Region, Myanmar (11°40'18.1"N, 99°13'30.1"E).

Etymology.

The specific name tenasserimicus refers to the type locality of this new species located on the Tenasserim Mountain Range, which forms the backbone of Indochina.

Diagnosis.

This species is distinguishable by its small size, angular penultimate whorl, low convex spire, and aperture that elongates and grows almost horizontally. Haploptychius tenasserimicus sp. nov. differs from H. burmanicus and H. blanfordi species by having oblique-ovate shells, prominent transverse ridges, higher spire, rounded penultimate whorl, and less deflected last whorl. This new species also differs from H. blaisei (Dautzenberg & Fischer, 1905) from Laos and Vietnam by having a relatively smaller shell (width ~ 8 mm), nearly flattened spire, angular penultimate whorl and rounded last whorl. In contrast, H. blaisei possesses a relatively larger shell (width ~ 10 mm), higher spire, rounded penultimate whorl, and compressed last whorl. In addition, H. tenasserimicus sp. nov. can be distinguished from H. dorri (Dautzenberg, 1894) from Vietnam (see Inkhavilay et al. 2016) by having a more depressed and larger shell (width ~ 8 mm), angular penultimate whorl, aperture longer and more axially deflected last whorl. Haplotychius dorri exhibits a depressed and smaller shell (width ~ 5 mm), smooth shell surface, rounded penultimate whorl, shorter aperture and last whorl less axially deflected from the vertical axis.

Description.

Shell sub-oblique heliciform, white and translucent; whorls 6; spire low convex with distinct suture. Shell surface glossy with fine transverse ridges that diminish below periphery; varices present. Embryonic shell ~ 2½ whorls with smooth surface; following whorls regularly coiled. Shell periphery angular; last whorl axially deflected. Aperture semi-ovate; peristome discontinuous, expanded and slightly reflected. Apertural dentition with one parietal lamella. Umbilicus open and shallow (Fig. 13A-C ).

Distribution.

This species was only collected from the type locality; limestone hills in primary forest in the Tanintharyi Region, Myanmar.

Remarks.

The genitalia information is not known.

Figures

Figure 13. A-C Haploptychius tenasserimicus sp. nov. A holotype CUMZ 13011 with apertural dentition B, C paratypes CUMZ 13012 from the type locality D Haploptychius heliakosus sp. nov. holotype CUMZ 13013 with apertural dentition.