11 Glessula gemma (Reeve, 1850)

Fig. 7 A – D, Table 1

Achatina gemma Reeve, 1850: pl. 22, fig. 123 (Benson MSS). Type locality: Barrackpore, Bengal. Pfeiffer 1853: 496. Benson 1860: 464.

Oleacina (Electra) gemma — Adams and Adams 1855: 105.

Achatina (Electra) gemma — Pfeiffer 1856: 168. Hanley and Theobald 1870: 17, pl. 36, fig. 7.

Cionella (Glessula) gemma — von Martens 1860: 254.

Stenogyra (Glessula) gemma — Nevill 1878: 170.

Glessula gemma — Pfeiffer and Clessin 1881: 331. Beddome 1906: 169. Pilsbry 1909: 97, pl. 13, figs 1, 3. Gude 1914: 428. Godwin-Austen 1920: 22. Raheem et al. 2014: 124, figs 78 b, 79 c, d. Preece et al. 2022: 235, 236.

Type specimen.

The type specimen could not be located in the UMZC nor in the NHMUK collections (Raheem et al. 2014; Preece et al. 2022).

Other material.

NHMUK 1946.10. 16.45–53 (9 shells; Fig. 7 A, B) ex. Benson collection from Bengal. Montawa Cave, Taunggyi City, Taunggyi District, Shan State, Myanmar. (20 ° 45 ' 15.9 " N, 97 ° 1 ' 3.4 " E): CUMZ 13069 (5 shells; Fig. 7 C, D).

Description.

Shell elongate ovate, solid, purple-black or yellowish colour, and with 6 ½ – 7 whorls. Apex blunt; protoconch ~ 2 whorls with smooth surface; subsequent whorls with smooth and glossy to weakly radial ribs. Spire grows evenly, is high and obtuse; whorls flatly convex; suture wide and shallow; last two whorls almost equal and largest. Aperture obliquely ovate; peristome moderately thickened and white; columella short, concave, and truncated. Umbilicus closed.

Distribution.

Glessula gemma was originally described from India and then its range extended to Bangladesh (Gude 1914; Godwin-Austen 1920; Raheem et al. 2014). In Myanmar, this species has been recorded from the Rakhine State and now in the Shan State.

Remarks.

The historical specimens NHMUK 1946.10. 16.45– 53 ex. Benson collection from Bengal is illustrated herein as an example.

Our specimens match well with the authenticated Reeve specimen of this species, although it is far from the type locality and previously reported region in the Rakhine State, Myanmar. Among all the Glessula species from Myanmar, G. gemma is superficially similar to G. latestriata from Shan State. In comparison, G. gemma has smooth shell surfaces, less turreted spire, and a shallow suture, while G. latestriata possesses well-developed grooves, a turreted and more attenuated spire, and a deeper suture.