Rishetia kentungensis ( Godwin-Austen, 1920 ) Man & Ablett & Lwin & Sutcharit & Panha, 2024

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

32 Rishetia kentungensis ( Godwin-Austen, 1920) comb. nov.

Fig. 14 E, F

Glessula kentungensis Godwin-Austen, 1920: 57, 58. Type locality: Mong Sing, Siam Boundary [Muang Sing District, Luang Namtha Province, Laos]. Inkhavilay et al. 2019: 49, fig. 20 b.

Type specimens.

Syntypes NHMUK 1903.7. 1.3650 [re-registered in error as 1986002] (3 shells + 1 juvenile; Fig. 14 E, F ) collected by Woodthorpe ex. Godwin-Austen collection from Mong Sing , Siam Boundary .

Other material.

NHMUK 1903.7. 1.3748 (4 shells) collected by Woodthorpe ex. Godwin-Austen collection from the Mekong River.

Diagnosis.

Shell elongate, turreted, and regularly attenuated; apex rounded, blunt and with very large embryonic shell; subsequent whorls nearly smooth throughout, and prominent irregularly spaced radial ridges near suture. Suture impressed and whorls slightly flattened. Aperture broadly ovate; columella strong, concave, and truncated.

Distribution.

This species was initially found in Laos; however, as noted by Godwin-Austen (1920), its presence in the Mekong River region is assumed to likely extend to the East Shan State.

Remarks.

The original description gave the measurements for only one shell and did not include an illustration. Godwin-Austen (1920) clearly states the collection locality and the catalogue number ‘ Type No. 3650 B. M. ’. The NHMUK collections contain a lot of four specimens from the Godwin-Austen ex. Woodthorpe collection with an original label stating ‘ Type’ and giving the collection locality as ‘ Mong Sing, Siam Boundary’. The two specimens match well with the original description, and shell dimensions are illustrated herein. Another specimen, lot ‘ No. 3748 B. M. ’ from the ‘ Mekong River’, is excluded from the type series of this nominal species.

Originally, the type locality was said to be from ‘ Mong Sing, Siam Boundary’; currently, this locality refers to Muang Sing District, Luang Namtha Province, Laos. The specimen NHMUK 1903.7. 1.3748, collected from the ‘ Mekong River’ by Colonel R. G. Woodthorpe, has a vague locality that could possibly encompass the East Shan State (formerly Keng Tung State) and the Bokeo and Luang Namtha provinces in Laos.

Figures

Figure 14. A – C Rishetia burrailensis maxwelli A, B specimen NHMUK 1903.7. 1.3742 from Somra Tracts, Somra Khulen Post, Burma and C specimen NHMUK 1903.7. 1.3744 from Somra Tracts, Somra Khulen Post, Burma D Rishetia hastula, neotype NHMUK 1906.1. 1.880 from Darjiling E, F Rishetia kentungensis, syntypes NHMUK 1903.7. 1.3650 from Mong Sing, Siam Boundary G Rishetia limborgi, holotype NHMUK 1903.7. 1.3200 from Tenasserim H, I Rishetia nathiana, syntypes NHMUK 1906.1. 1.2206 from Bassein District.