Glessula von Martens, 1860

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 Glessula von Martens, 1860

Electra Albers, 1850: 194 . [non Lamouroux 1816 (Bryozoa)]. Type species: Achatina ceylanica Pfeiffer, 1845 . Adams and Adams 1855: 105. Pfeiffer 1856: 168.

Cionella (Glessula) — von Martens in Albers 1860: 254. Pfeiffer and Clessin 1881: 329.

Stenogyra (Glessula) — Nevill 1878: 166.

Glessula — Tenison-Woods 1888: 1053. Beddome 1906: 160. Pilsbry 1908: 50. Gude 1914: 377. Zilch 1959: 343. van Benthem Jutting 1952: 373, 374. Schileyko 2011: 11.

Type species.

Achatina gemma Reeve, 1850 by original designation.

Diagnosis.

Shell ovate-conical in shape; spire low or high conical, and regularly attenuated; embryonic whorls smooth or with striations; subsequent whorls with equally or irregularly spaced radial striations or ribs. Aperture oblique, narrow to wide, and ovate; columella concave and truncated, and columellar margin not expanded. Penis large, thick, and moderately long; epiphallus short, stout, terminally pointed, and curved; flagellum present (rarely absent) with comb-like or hand-like structures; epiphallic caecum absent; vagina muscularly and nearly equal to ~ 1 / 5–2 / 5 of penis length.

Remarks.

Superficially, Glessula and Rishetia are similar in having a concave and truncated columella, but they differ in their shell shape and genital structure ( Godwin-Austen 1920; Raheem et al. 2014; Budha et al. 2017). In terms of shell morphology, Glessula can be differentiated by its ovate-conical shape, short spire, large and blunt embryonic whorls, while Rishetia possesses a slender, conical-shaped elongate spire which narrow and rather acute embryonic whorls (Table 2 ). Regarding the genital characters, Rishetia exhibits a simple, tubular-shaped flagellum with the epiphallic caecum present (Table 3 ), while Glessula displays a well-developed comb-like flagellum (appendage) and the epiphallic caecum absent ( Budha et al. 2017); except G. mandalayensis sp. nov. which has no flagellum. Likewise, Glessula is also distinct from Curvella by its concave and truncated columella, not expanded columellar margin, and obliquely narrow and ovate aperture, while Curvella possesses a straight columella, expanded columellar margin, and more vertical, higher, and broader oblong aperture.

Glessula is widely distributed throughout the Indian subcontinent, and nearly 100 species have been described ( Godwin-Austen 1920; Schileyko 1999; Ramakrishna et al. 2010; MolluscaBase 2023). Among the sporadic species recorded in Southeast Asia, Myanmar has 12 species ( Gude 1914; Godwin-Austen 1920), while two species, G. latestriata von Möllendorff, 1899 and G. paviei Morlet 1893 , have been recorded from Vietnam, Laos, and Thailand, and another two species, G. sumatrana ( von Martens, 1864) and G. wallacei ( Pfeiffer, 1856) from Indonesia ( Tenison-Woods 1888; van Benthem Jutting 1952; Solem 1966; Schileyko 2011; Inkhavilay et al. 2019).

In this study, only five species including a new species, G. blanfordiana Nevill, 1877 , G. feddeni Godwin-Austen, 1920 , G. gemma (Reeve, 1850) , G. latestriata , and G. mandalayensis sp. nov. have been collected and re-described.