Georissa meghalayaensis sp. nov.

urn:lsid:zoobank.org:act: BA54A3F3-52D5-4CA5-8949-3C03FFC0FAF8

Figs 3, 7

Etymology

Named after the state where the species has been collected.

Type material

Holotype

INDIA • preserved in alcohol; Meghalaya, Krem Puri [‘Krem’ means ‘cave’ in Khasi language of Meghalaya]; 25.278599° N, 91.559557° E; 1261 m a.s.l.; 28 Dec. 2022; Nipu Kumar Das leg.; ZSI / SRC /LM2161.

Paratypes

INDIA • 2 specs (preserved in alcohol); same data as for holotype; ZSI/SRC/LM2162a, ZSI / SRC / LM2162b.

Measurements (in mm)

Holotype: SH 1.91, SW 1.56, SH/SW 1.22, AH 0.91, AW 0.94, AH/AW 0.97, SpH 0.98, SpW 1.35, PrW 0.47. Paratype ZSI/SRC/LM2162a: SH 2.26, SW 1.72, SH/SW 1.31, AH 1.03, AW 0.98, AH/AW 1.05, SpH 1.21, SpW 1.44, PrW 0.52.

Description of the shell

Shell dextral, small, oval, turbinate; spire acuminate; colour orangish-red; shell sculpture meshed pattern, spiral ribs present, somewhat strong, very densely arranged, 3–4 spiral ribs/ 0.1 mm on the body whorl, and around regularly spaced across shell surface immediately after protoconch, sometimes distorted by radial ribs or growth lines, radial ribs present, irregular and weakly sculptured across the shell; suture well-impressed with slightly extended shoulder; umbilicus narrow; whorls 3.5, convex; protoconch/ teleoconch transition zone distinct; protoconch dark brownish, round and globular, nearly smooth with pits, whorls 1.5; aperture ovate, oblique or sub-vertical; peristome simple, thin and continuous, parietal lip angular, palatal and basal lips or edges roundish; columellar callus dark brownish, prominent and oblique; operculum oval, calcareous, multispiral with growth lines.

Differential diagnosis

Georissa meghalayaensis sp. nov. shows similarity in shell shape with G. sarrita (W.H. Benson, 1851), G. mawsmaiensis Das & Aravind, 2021, G. pyxis (W.H. Benson, 1856), and G. hungerfordi Godwin-Austen, 1889, but differs in having mesh-like striations across the shell surface, unlike the others, with strong or sharp spiral striations and in shell colour (yellowish in G. sarrita vs orangish-red in G. meghalayaensis). There are also denser spiral striations in G. meghalayaensis compared to the four above-mentioned species. The mesh-like shell sculpture pattern of G. meghalayaensis is similar to the scaly G. niahensis Godwin-Austen, 1889 (Niah Hills, Borneo), but it differs in the shape of the first whorl of the scaly teleoconch. Georissa meghalayaensis is slightly smaller, with fewer whorls, and less densely arranged spiral striations on the shell compared to G. digitinota Klongkaew, Poeaim & Dumrongrojwattana, 2024 (Satun Province, Thailand). Georissa monterosatiana Godwin-Austen & Neville, 1879 (Perak State, Malaysia) differs from G. meghalayaensis in having a small, elongate-conic shell with strong, regularly spaced spiral ribs on the shell surface. A detailed comparison of various shell features of G. meghalayaensis with its congeners is provided in Table 1, and the shell size comparison is shown in Fig. 7A.

Habitat and distribution

Live individuals of Georissa meghalayaensis sp. nov. were collected at the edge of the cave entrance on a wet, moss-covered rocky wall, with 50% canopy cover. Georissa meghalayaensis is known only from the type locality.

Remarks

The holotype and paratypes differ slightly in shell sculpture. The body whorl of the paratype is finer and more polished than that of the holotype. Additionally, the aperture neck of the paratypes shows stronger, more distinct, and densely packed radial ribs, whereas the holotype has only very fine ribs or a nearly polished neck, which are nearly invisible to the naked eye.