Georissa sepulutensis, Khalik, Mohd Zacaery, Hendriks, Kasper, Vermeulen, Jaap J. & Schilthuizen, Menno, 2018

Khalik, Mohd Zacaery, Hendriks, Kasper, Vermeulen, Jaap J. & Schilthuizen, Menno, 2018, A molecular and conchological dissection of the " scaly " Georissa of Malaysian Borneo (Gastropoda, Neritimorpha, Hydrocenidae), ZooKeys 773, pp. 1-55 : 1

Georissa sepulutensis sp. n.

Georissa scalinella van Benthem-Jutting: Schilthuizen et al. 2005: 134-135 (non G. scalinella van Benthem-Jutting, 1966).

Type locality.

Sepulut valley, Gua Pungiton near Kg. Labang, Sabah, Malaysia (04°42.41'N, 116°36.04'E).

Type material.

Holotype. Sepulut valley, Gua Pungiton near Kg. Labang, Sabah, Malaysia (04°42.41'N, 116°36.04'E); BOR/MOL 13922 (leg. M Schilthuizen). Paratypes. Simbaluyon limestone hill, Sabah: RMNH/MOL 333905 (18), RMNH/MOL 333982 (23), RMNH/MOL 334006 (7). Tinahas, Sabah: RMNH/MOL 333984 (>50), RMNH/MOL 334013 (>50). Sepulut valley, Gua Sanaron, Sabah (04°42.05'N, 116°36.01'E): BOR/MOL 36, BOR/MOL 39, BOR/MOL 13870 (1). Sepulut Valley, Gua Pungiton, Sabah (04°42.41'N, 116°36.04'E): BOR/MOL 12278. Sepulut valley, Batu Punggul, Sabah: RMNH/MOL 187650, BOR/MOL.40. Baturong, Sabah: BOR/MOL 37.

Etymology.

Named after the town of Sepulut, Sabah, Malaysia, near which the type locality Gua Pungiton, as well as the other known localities, is located.

Description.

Protoconch. Color: red to brown. Sculpture: smooth to meshed - semi-oval mesh to undefined mesh pattern. Mesh width: 7-17 µm. Teleoconch. Color: red. First whorl: flat to rounded at the shoulder. Body whorl: rounded, with number of whorls: 2-2 ¾. SH: 1.11-1.52 mm, SW: 1.11-1.37 mm, SI: 0.94-1.07. Shell sculpture. Radial sculpture: absent, only weak growth lines are visible. Spiral sculpture: present, and strongly sculpted. Scales: a series of pointed vertical scales, acute and highly projected, and regularly spaced. Aperture. Shape: oval and tilted below. Basal side: rounded, angular at the columellar region. Parietal side: straight, palatal edge attached to the body whorl. AH: 0.62-0.81 mm, AW: 0.76-0.96 mm, AI: 0.72-0.87. Holotype dimension. SH: 1.34 mm, SW: 1.23 mm, AH: 0.65 mm, AW: 0.82 mm.

Cross diagnosis.

Unlike Georissa kinabatanganensis , G. sepulutensis has a series of scales only at the shoulder, which makes it resemble in habitus and scale characters G. pyrrhoderma from Gunung Silabur, Sarawak.

Distribution.

Distributed in the Sepulut Valley, Sabah; known from the following limestone localities: Simbaluyon, Sanaron, Tinahas, and Pungiton.

Molecular analysis.

ML and Bayesian analyses show G. sepulutensis (16S: n = 10; CO1: n = 2) as two clades with 93% BS and 97% PP, and as the sister species to G. kinabatanganensis sp. n.

Discussion.

Georissa sepulutensis and G. kinabatanganensis were previously included in G. scalinella (van Benthem-Jutting, 1966). Based on the genetic and morphological distinctness, we here consider them as separate species.