Tortaxis Pilsbry, 1906

Man, Nem Sian, Ablett, Jonathan D., Lwin, Ngwe, Sutcharit, Chirasak & Panha, Somsak, 2024, Contributions on a small collection of the former Subulinidae Fischer & Crosse, 1877 (Eupulmonata, Achatinoidea) with catalogue of the Glessula and Rishetia species recorded from Myanmar, ZooKeys 1208, pp. 173-239 : 173-239

Genus Tortaxis Pilsbry, 1906

Tortaxis Pilsbry, 1906: 5, 6. Zilch. 1959: 347. Schileyko 1999: 534. Schileyko 2011: 10. Do and Do 2014: 455.

Type species.

Achatina erecta Benson, 1842 , by original designation.

Diagnosis.

Shell slender, cylindrically shaped; spire high, mostly turreted, and gradually attenuated; embryonic whorls smooth, and subsequent whorls with nearly smooth to strong radial ribs. Aperture vertical, narrow, and oblong; columella concave or straight and with spiral fold below; columellar margin with or without expansion near umbilicus. Umbilicus narrowly opened or closed.

Remarks.

Tortaxis can be distinguished from other subulinid taxa from Myanmar, namely Allopeas , Opeas , and Bacillum , by having a slender, cylindrical, and turreted spire, flatter whorls, smooth embryonic whorls, a large and rounded apex, and a distinct spiral fold on the columella (Table 2 ).

The genus is mainly distributed in Southeast Asia and southern China and comprises 14 extant species ( Pilsbry 1906; Schileyko 1999; MolluscaBase 2023) and one Miocene-amber fossil from China ( Yu et al. 2023). In Indochina, nine species have been reported from Vietnam, and only one species from Thailand ( Panha 1998; Schileyko 2011; Do and Do 2014). In this study, we propose one new species which marks the first record of the genus in Myanmar.