Oxytesta siyomensis Godwin-Austen, 1918

Gurumayum, Shantabala Devi, 2022, A short note on rediscovering of two endemic ariophantid snails of the genus Oxytesta Zilch, 1956 after a gap of hundred years, Records of the Zoological Survey of India 122 (4), pp. 367-370 : 368-369

Oxytesta siyomensis Godwin-Austen, 1918

1916. Oxytes siyomensis Godwin-Austen, Rec. Indian Mus. , 8: 595, pl.

52. figs 3, 3a, 3b.

Material Examined: ZSI/IV/ APRC /M-319, 1 ex. Ramsingh (28°14’05.7”N 95°13’05.1”E, 336 msl), Upper Siang district, Arunachal Pradesh, 27.10.2017. coll., G. Maheswaran, et al.,; ZSI/ IV/ APRC / M-321, 2 ex. Ramsingh (28°38’41.0”N 94°59’54.0” E, 356 msl), Upper Siang district , Arunachal Pradesh, 01.12.2020.10.2017, coll., SD Gurumayum .

Shell Measurements: Largest: 21mm (width), 8mm (axis); Smallest: 19mm (width), 7mm (axis).

Original type description by Godwin-Austen : Locality. Siyom Valley, Abor Hills (Long. 94° 40’ and Lat. 28° 30’) high up [Capt. Oakes, R.E.).

Shell openly perspectively umbilicated, rather solid, lenticular depressed, sharply keeled; sculpture fine close transverse striation, on base close pitting; colour bleached in type, pale umber in a second specimen; spire fairly high, apex rounded, sides flatly convex; suture linear; whorls Shantabala Devi Gurumayum 5, regularly increasing; aperture semilunate, subvertical; peristome: upper margin sinuate, compressed towards keel so as to be concave, lower margin oblique. Size: major diameter 25*0, minor 21-5, alt. axis 7-0 mm. This differs from aborensis, a close ally, in being more solid and not so extremely flat. A smaller specimen from the same valley has the peristome much thickened. Major diam. 24*0, alt, axis 68 mm.

Remarks: Oxytesta siyomensis closely resembles O. aborensis however differs by having a more solid shell and not so extremely flat dorsal side. The peristome of O. siyomensis has more sudden depression as compared to O. aborensis .