Rishetia Godwin-Austen, 1920

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 Rishetia Godwin-Austen, 1920

Glessula (Rishetia) Godwin-Austen, 1920: 7.

Rishetia — Schileyko 1999: 532. Raheem et al. 2014: 138, 139. Budha et al. 2017: 137. Preece et al. 2022: 127.

Type species.

Achatina tenuispira Benson, 1836 by original designation.

Diagnosis.

Shell slender and conical; spire high, turreted, and regularly attenuated; embryonic whorls smooth or with striations and subsequent whorls have thick or fine and equally or irregularly spaced radial ribs. Aperture oblique, narrow to broad, and ovate shape; columella concave and truncated; columellar margin not expanded. Penis large, thick, and moderately long; epiphallus relatively long; flagellum present with tubular shape; epiphallic caecum present; vagina enlarged, short ~ 1 / 2 of penis length.

Remarks.

Originally, Godwin-Austen (1920) proposed Rishetia as a subgenus of Glessula , which Schileyko (1999) raised to the generic level, followed by Raheem et al. (2014), Budha et al. (2017), and Preece et al. (2022). Rishetia can be distinguished from Glessula by having a slender elongate-conical shell with a tubular-shaped flagellum and epiphallic caecum present, while Glessula processes an ovate-conical shell with a comb-like flagellum and epiphallic caecum absent (Tables 2 , 3 ).

Rishetia can generally be differentiated from Bacillum by having a narrowly attenuated shell, convex and smaller apex, straight columella, and weak striations; Bacillum has a cylindrical shell, large and rounded apex, more concave columella, and stronger radial striations (Table 2 ). More information on the genitalia as well as a molecular phylogeny based on multiple species will clarify the systematic relationship of these two genera.

This genus has been documented in India, Sri Lanka, Bangladesh, and Nepal, with its presence in Southeast Asia limited to Myanmar ( Godwin-Austen 1920; Schileyko 1999; Raheem et al. 2014; Budha et al. 2015, 2017). Currently, 23 species are recognised; among these, eleven species and subspecies have been documented from Myanmar ( Godwin-Austen 1920; MolluscaBase 2023).