Georissa kinabatanganensis , 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

publication ID

publication LSID

persistent identifier

taxon LSID

treatment provided by

ZooKeys by Pensoft

scientific name

Georissa kinabatanganensis

sp. n.

Georissa kinabatanganensis  sp. n.

Type locality.

Bukit Keruak, near Kinabatangan river, Sandakan, Sabah, Malaysia (05°31.385'N, 118°17.113'E).

Type material.

Holotype. Bukit Keruak, near Kinabatangan river, Sandakan, Sabah, Malaysia (05°31.38'N, 118°17.11'E): BOR/MOL 13921 (leg. M Schilthuizen). Paratypes. Bukit Keruak, near Kinabatangan river, Sandakan, Sabah (05°31.38'N, 118°17.11'E): MZU/MOL 17.26 (>50). BOR/MOL 1458, BOR/MOL 11656, BOR/MOL 11665, BOR/MOL 11711, BOR/MOL 13871. Batu Pangi, Sabah: BOR/MOL 1455. Batu Tomanggong, Sabah: BOR/MOL 1456, BOR/MOL 1457, BOR/MOL 10530.


Named after the district of Kinabatangan, Sabah, Malaysia, where the type locality Bukit Keruak is located.


Protoconch. Color: orange. Sculpture pattern: smooth to meshed - rounded to undefined mesh pattern. Mesh width: 14-21 µm. Teleoconch. Color: orange. First whorl: flat and angular at the shoulder. Subsequent whorls: angular, slightly rounded at the periphery, with number of whorls: 2-2 ¼. SH: 1.00-1.32 mm, SW: 1.13-1.37 mm, SI: 0.85-0.99. Shell sculpture. Radial sculpture: absent, only weak to strong growth lines are visible. Spiral sculpture: present, and strongly sculpted, with continuous to discontinuous ribbings. Scales: two series of diagonal vertical scales, widely spaced in between, both series are strongly sculpted, broad, and the scales are regularly placed. Aperture. Shape: oval. Basal side: rounded, angular at the columellar region. Parietal side: straight, palatal edge attached to the body whorl. AH: 0.54-0.66 mm, AW: 0.75-0.86 mm, AI: 0.65-0.80. Holotype dimension. SH: 1.00 mm, SW: 1.18 mm, AH: 0.54 mm, AW: 0.78 mm.

Cross diagnosis.

Georissa kinabatanganensis  has less variation in shell sculpture compared with G. hosei  and G. scalinella  . G. kinabatanganensis  has two series of acutely projected scales on the whorls. In some cases, the second scale series is weaker than the first, and creates a series of nodular structures at the periphery. Often the shell is wider than high, which gives it a flattened appearance. In addition, G. kinabatanganensis  has widely spaced between the scale series, similar to G. muluensis  .


Known from Bukit Keruak, Batu Tomanggong, and Pangi, in the region of Kinabatangan, Sabah.

Molecular analysis.

RAxML and Bayesian analyses show G. kinabatanganensis  (16S: n = 6; CO1: n = 6) forming a clade with 97% BS and 97% PP and as a sister clade to G. sepulutensis  .


Georissa kinabatanganensis  is the only species in "scaly group" Georissa  to have a flat shell habitus, all examined individuals have a shell that is broader than high.