Georissa quinquelirata Klongkaew, Poeaim & Dumrongrojwattana sp. nov.

Figs 2 A, 4 A – D, 5 A – D

Type material.

Holotype • ZRCBUU 0900 (Fig. 2 A). SH = 2.45 mm, SW = 1.63 mm, AH = 0.80 mm, AW = 0.91 mm, W = 4.25–4.5. Paratype • ZRCBUU 0901 (Fig. 4 A – D) (13 shells); Shell measurements: SH = 1.91–2.36 mm (2.10 ± 0.15 mm), SW = 1.37–1.60 mm (1.46 ± 0.07 mm), AH = 0.71–0.86 mm (0.78 ± 0.06 mm), AW = 0.80–0.92 mm (0.86 ± 0.04 mm), W = 3.75–4.5 (all type material from type locality; 25 February 2023, P. Dumrongrojwattana leg).

Type locality.

Thailand, Pathawi limestone hill, Thap Than district, Uthai Thani Province; 15 ° 28 ' 26.9 " N, 99 ° 45 ' 25.0 " E.

Etymology.

The specific designation “ quinquelirata ” indicates the number of lirae on the whorl.

Diagnosis.

Shell minute, ovately conical, orangish to brownish, protoconch round to slightly ellipsoid and wrinkled sculpture. Body whorl have about 5–6 prominent carinae, and between carinae have weak growth lines. Aperture semi-rounded. Umbilicus closed. Operculum corneous with apophysis, paucispiral, opaque white, and semi-rounded.

Description.

Shell minute, dextral, orangish to brownish, ovately conical with 4.25–4.5 whorls (Fig. 2 A). Protoconch orange, about one whorl, round to slightly ellipsoid, covered with wrinkled sculpture (Fig. 4 B, C). Teleoconch orange, 3.25–3.5 whorls. Body whorl peripherally rounded, sculptured with 5–6 prominent carinae, weak growth lines between carinae, intersected by weak oblique growth lines. Basal part of body whorl with approximately 9–10 densely spaced spiral cords (Figs 2 A, 4 A). Suture incised. Aperture semi-rounded. Peristome thin, sharp, unexpanded or thickened, not reflected. Umbilicus closed (Figs 2 A, 4 A). Operculum paucispiral, nucleus submarginal, corneous, opaque white, semi-rounded, thin, smooth outside surface with apophysis, inside surface with an arched peg arising from base (Fig. 4 D).

Radula.

Ribbon-like, slender, longer, and delicate towards the outside, rhipidoglossate (Fig. 5 A – D). Central tooth five small teeth, trapezoid shape. Lateral teeth five teeth, claw-like, with 9–13 alternately long and short denticles decreasing in size from the first lateral tooth toward the 5 th lateral tooth. Marginal teeth two teeth, claw-like, with 12–14 equal-sized denticles. Radula formula 2: 5: 1 + 1 + 1 + 1 + 1 + 1: 5: 2.

Differential diagnosis.

Georissa quinquelirata sp. nov. resembles G. hungerfordi Godwin-Austen, 1889 from Sabah, Borneo, Malaysia, Georissa hungerfordi differs in having a less convex body whorl, a smooth sculpture, and more spiral lirae (7–10 lirae instead of 5–6 carinae). This new species is also like G. liratula Stolixzka, 1871 from Domotha, Moulmein, but differs in having a more slender shell with fewer spiral lirae.