Haploptychius burmanicus (Blanford, 1865)

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 burmanicus (Blanford, 1865)

Fig. 10D

Streptaxis burmanica Blanford 1865: 81, 82. Type locality: Tongoop, Arakan [Toungup, east of Arakan Hills, Thandwe District, Rakhine State, Myanmar].

Streptaxis burmanicus [sic] - Pfeiffer 1868: 444. Stoliczka 1871: 163, pl. 7, figs 5-7. Nevill 1878: 2. Blanford and Godwin-Austen 1908: 6, fig. 5. Richardson 1988: 251.

Haploptychius burmanicus - Kobelt 1906: 145: pl. 57, figs 19, 20, pl. 62, figs 1-3. Richardson 1988: 213. Ramakrishna et al. 2010: 190.

Material examined.

Possible syntype NHMUK 1906.2.2.199 (2 adults + 1 juvenile; Fig. 10D ) ex. W.T. Blanford collection from Tongoop, Arakan [Taungup, Rakhine State].

Description.

Shell oblique-heliciform, white, and translucent; whorls 6; spire convex with distinct suture. Shell surface glossy with fine transverse ridges that diminish below periphery. Embryonic shell ~ 2½ whorls with smooth surface; following whorls regularly coiled. Shell periphery rounded; last whorl axially deflected. Aperture semi-ovate; peristome continuous; sometimes discontinuous, thin, expanded, and slightly reflected. Apertural dentition with one strong parietal lamella. Umbilicus open and deep (Fig. 10D ).

Distribution.

Haploptychius burmanicus is still known only from the type locality in southern Myanmar ( Blanford 1865). Outside Myanmar, it is also reported from Mizoram in India ( Ramakrishna et al. 2010); however, this record needs to be verified.

Remarks.

This species highly resembles H. blanfordi in shell form, but H. burmanicus is more globosely heliciform, with a higher spire and only one parietal lamella. Without anatomical information, the generic placement of this species is still tentative, and we retain this as Blanford and Godwin-Austen (1908). In addition, H. perlissus Vermeulen et al. 2019 from Vietnam ( Vermeulen et al. 2019: figs 49-51) can be distinguished from H. burmanicus by having an oblique-ovate shell, less extended penultimate whorl from the last whorl, lower to nearly flattened spire, the palatal side is almost straight, basal side rounded, and columellar side broadly rounded, whereas H. burmanicus has a higher spire, more compressed shell, and the last whorl is more axially deflected.

Figures

Figure 10. A-C Haploptychius blanfordi A syntype NHMUK 1888.12.4.777 - 779 from Pegu with apertural dentition B specimen NHMUK 1906.2.2.338 from Akouktoung, Pegu C specimen NHMUK 1909.3.15.71 from Pegu D Haploptychius burmanicus, syntype NHMUK 1906.2.2.199 from Tongoop, Arakan with apertural dentition.