Georissa muluensis, 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 muluensis sp. n.

Type locality.

Lagang Cave, Mulu National Park, Mulu, Sarawak, Malaysia (04°03.06'N, 114°49.37'E).

Type material.

Holotype. Lagang Cave, Mulu National Park, Mulu, Sarawak, Malaysia (04°03.06'N, 114°49.37'E): MZU/MOL 17.86 (leg. MZ Khalik and SK Reduan). Paratypes. Lagang Cave, Mulu National Park, Mulu, Sarawak (04°03.06'N, 114°49.37'E): MZU/MOL 17.30 (13), MZU/MOL 17.31 (9).

Other material.

Deer Cave, Mulu National Park, Mulu, Sarawak: JJV 10533 (this sample, approximately 120 individuals, also contains specimens of G. hadra ), JJV 10554 (this sample contains 5 individual of G. muluensis , 1 individual G. hadra ), JJV 10533 (this sample, approximately 150 individuals, also contains specimens of G. hadra and G. kobelti ). Mulu N.P., Mulu, Sarawak: JJV 10527.

Etymology.

Named after Mulu National Park, Sarawak, Malaysia, the type locality.

Description.

Protoconch. Color: yellow. Sculpture pattern: meshed - ellipsoidal mesh shape. Mesh width: 16-26 µm. Teleoconch. Color: yellow. First whorl: shouldered, above the shoulder flat, nearly horizontal; below the shoulder flat, cylindrical, but abruptly withdrawn into the deeply incised suture. Subsequent whorls: convex to rounded. SH: 1.67-2.05 mm, SW: 1.57-1.79 mm, SI: 1.08-1.18. Total number of whorls: 2 ¼ -3. Shell sculpture. Radial sculpture: absent, only weak to strong growth lines are visible. Spiral sculpture: present, consisting of thin, but strongly sculpted and continuous ribs. Scales: two to three series of tall and diagonal scales, regularly spaced, the upper scale series always stronger than the lower ones, weaker series appear later at the spire or consist only of randomly spaced arrays of acute nodules, widely spaced between the first and second scale series, more densely spaced later. Aperture. Shape: rounded to slightly oval. Basal side: rounded, angular at the columellar region. Parietal side: straight to slightly curved. AH: 0.82-0.98 mm, AW: 1.03-1.18 mm, AI: 0.77-0.83. Holotype dimension. SH: 1.67 mm, SW: 1.53 mm, AH: 0.82 mm, AW: 1.07 mm.

Cross diagnosis.

The wide spacing of the major spiral scale series of G. muluensis is similar to G. kinabatanganensis , but G. muluensis has a more elongated shell shape, rather than the more flattened habitus of G. kinabatanganensis . In general shell shape and sculpture G. muluensis also resembles G. hadra , which, however, is larger and more elongated.

Distribution.

Known only from the small area of Lagang Cave, Mulu National Park, Mulu, Sarawak, Malaysia.

Molecular analysis.

ML and Bayesian analyses show that the individuals of G. muluensis (16S: n = 4; CO1: n = 4) form a monophyletic group with 100% BS and 100% PP, which is the sister group of G. hadra .