Georissa sarrita (W.H. Benson 1851)

Figs 4, 7

Material examined

INDIA • 8 shells; Mizoram, Champhai district, Tuipui, approximately 2 km NW of the bridge over Tuipui River; 23.46694° N, 93.2525° E; 851 m a.s.l.; 31 Jan. 2019; Nipu Kumar Das leg.; AT/2019/ LS5010 to 5017.

Measurements (in mm)

Shell 1 (AT/2019/ LS 5010, Fig. 4A–F): SH 1.63, SW 1.12, SH/SW 1.45, AH 0.68, AW 0.69, AH/AW 0.98, SpH 0.95, SpW 0.99, distance between spiral ribs on body whorl (apertural view) 0.09, PrW 0.35, OH 0.51, OW 0.38. Shell 2 (AT/2019/ LS 5011, Fig. 4G–M): SH 1.74, SW 1.24, SH/SW 1.40, AH 0.73, AW 0.74, AH/AW 0.99, SpH 1.00, SpW 1.10, distance between spiral ribs on body whorl (apertural view) 0.10, PrW 0.37.

Description of shell

Shell dextral, small, oval, turbinate; spire acuminate; colour yellowish; shell sculpture spiral ribs present, strong, widely arranged and at nearly regular interval across shell surface, 6 very strong spiral ribs on body whorl above aperture (in apertural view), spiral ribs sometimes distorted or discontinuous due to growth lines, very densely spaced spiral ribs on basal part of body whorl or in umbilical view, radial ribs absent, weak growth lines across shell, mesh visible in umbilical view, nearly indistinct on rest of shell; suture well-impressed with narrow shoulder; umbilicus narrow; whorls 3.5–4, convex; protoconch/ teleconch transition zone distinct; protoconch brownish or horny, round and globular, nearly smooth with evenly distributed pits, Wh 1.25; aperture round or slightly ovate, oblique or sub-vertical; peristome simple, thin and continuous, parietal lip angular, palatal and basal lips or edge roundish; columellar callus prominent and oblique, shiny or sometimes transparent; operculum thick, oval, multispiral or concentric, with characteristic calcareous slender peg on inner side or surface, OH 0.51 mm, OW 0.38 mm.

Damotha, near Moulmein, Myanmar Phie Than, Tenasserim, Myanmar Thyet-Mio, Myanmar Ataran River Valley, near Moulmein, Myanmar Ava, Myanmar Near Moulmein in Farm Caves, Myanmar Farm Caves, near Moulmein, Myanmar

Habitat and distribution

The shells of G. sarrita were found in the soil-leaf litter sample collected near Tuipui village, Champhai district, Mizoram, whereas the type material of the species was originally reported from mosses in deep valleys near Cherrapunji, Meghalaya (Benson 1851). The temperature at the soil, soil leaf litter depth, and % canopy cover at the new collection site were 21–22°C, 2–3.5 cm, and 30%, respectively. Other gastropod species, namely Glessula sp. and Tanychlamys sp., were also present at the collection site. The site was located by the roadside near a dry stream with abundant leaf litter.

Remarks

The present material is slightly smaller (SH 1.63–1.74 mm, SW 1.12–1.24 mm) than the dimensions given in the original description (SH 2 mm, SW 1.25 mm) (Benson 1851). Benson’s collection, including the syntype specimen (UMZC I.103725.A), is worn and exhibits whitish or yellowish colouration, whereas the new shells from Mizoram are reddish. This new collection represents the first record of Georissa from Mizoram, NE India.