Conchological and molecular analysis of the " non-scaly " Bornean Georissa with descriptions of three new species (Gastropoda, Neritimorpha, Hydrocenidae) Author Zacaery Khalik, Mohd Author P. Hendriks, Kasper Author J. Vermeulen, Jaap Author Menno Schilthuizen, text ZooKeys 2019 840 35 86 http://dx.doi.org/10.3897/zookeys.840.33326 journal article http://dx.doi.org/10.3897/zookeys.840.33326 1313-2970-840-35 C607C2FDC17644FABBC582D561C6434C C607C2FDC17644FABBC582D561C6434C Georissa insulae sp. n. Figure 14 A-K Georissa williamsi Godwin-Austen: Clements et al. 2008 : Appendix D; Phung et al. (2017) , fig. 8C. Type locality. Pulau Mantanani Besar, Sabah, Malaysia ( 06°43.06'N , 116°20.50'E ). Type material. Holotype. Pulau Mantanani Besar, Sabah, Malaysia ( 06°43.06'N , 116°20.50'E ): MZU/MOL 18.01 (Fig. 14 A-C ). Paratypes: Pulau Mantanani Besar, Sabah, Malaysia ( 06°43.06'N , 116°20.50'E ): MZU/MOL 18.02 (Fig. 14 D-K ). Pulau Mantanani Besar, West Coast Province, Sabah: JJV 9845 (8), JJV 9860 (>50), BOR/MOL 3718, BOR/MOL 7161 (1), BOR/MOL 7174 (9). Pulau Lungisan, Sabah: BOR/MOL 3744. Kinabalu N.P., Poring Hot Springs, along path to waterfall, West Coast Province, Sabah: JJV 13003 (1). Gua Mundau, Pitas, Sabah ( 06°33.02'N , 116°52.07'E ): BOR/MOL 4373 (1, broken shell). Figure 14. Georissa insulae sp. n. A-C Holotype: MZU/MOL 18.01 D-K paratype: MZU/MOL 18.02 A, D shell apertural view B shell side view C shell rear view E, F shell cross-section from 3D model G, H operculum frontal and ventral view from 3D model I shell top view J protoconch side view K close up of protoconch from top at 1000 x magnification. Scale bars: 500 µm ( A-I ); 200 µm (J); 10 µm (K). Etymology. The name is a genitive singular of the Latin word insula, meaning 'island' , which refers to the Mantanani islands, the main collecting locality. Description. Protoconch. Colour: orange. Sculpture pattern: a mix of rounded and ellipsoidal sculpture. Mesh width: 1.5-12.0 µm . Teleoconch. Colour: orange. First whorl: convex. Subsequent whorls: convex. Suture: well-impressed. Shoulder: narrow. Number of whorls: 2 3/4- 3 1/4 . SH: 1.78-2.11 mm. SW: 1.21-1.40 mm. SI: 1.42-1.51. Shell sculpture. Radial sculpture: absent, weak growth lines present throughout the shell surface. Spiral sculpture: present, strong, regularly spaced, ca. 10-12 spiral ribs on the body whorl of the adult individual, developed immediately after the protoconch; more densely spaced spiral ribs at the basal part of the body whorl, becoming weaker closer to the columellar region. Aperture. Shape: rounded to slightly ovoid, straight to concave parietal side, palatal edge contiguous with the body whorl, basal side convex. AH: 0.66-0.79 mm. AW: 0.74-0.84 mm. AI: 0.89-0.94. Holotype dimensions. SH: 2.11 mm, SW: 1.40 mm, AH: 0.79 mm, AW: 0.84 mm. Diagnosis. Georissa insulae is characterised by the strong and regularly spaced spiral ribs throughout the entire shell. This shell sculpture is similar to that of G. hungerfordi and G. trusmadi , but less raised than in these two species. Georissa insulae has a greater number of spiral ribs, ca. 10-12 ribs on its shell compared to these two species. The shell habitus is distinctly elongated compared to other spirally ribbed Bornean Georissa . Distribution. Known from islands of Mantanani Kecil, Mantanani Besar, Lungisan, and on the mainland from Pitas to Kinabalu National Park, Sabah. Molecular analysis. ML and Bayesian analyses of G. insulae (16S: n = 4) show that G. filiasaulae form one clade with 100% BS and 100% PP. Sister to the rest of "non-scaly" Georissa , except for G. hungerfordi + G. gomantonensis + G. filiasaulae .