Georissa bangueyensis Smith, 1895

Zacaery Khalik, Mohd, P. Hendriks, Kasper, J. Vermeulen, Jaap & Menno Schilthuizen,, 2019, Conchological and molecular analysis of the " non-scaly " Bornean Georissa with descriptions of three new species (Gastropoda, Neritimorpha, Hydrocenidae), ZooKeys 840, pp. 35-86 : 70-72

Georissa bangueyensis Smith, 1895 Figures 1H, 19 A–K

Georissa bangueyensis Smith, 1895: 125, Plate IV fig. 16; Thompson and Dance 1983: 126.

Type locality.

Banguey Island, N. Borneo.

Type material.

Lectotype (Designation by Thompson and Dance 1983). Banguey Island, N. Borneo: NHMUK 1893.6.7.9 (Fig. 1H).

Other material.

Banggi Island, South end, Kudat province, Sabah (07°06.32'N, 117°5.07'E): RMNH/MOL 152746, JJV 1423, JJV 1451, JJV 9467, JJV 9497. Pulau Banggi, Kudat Dist., Sabah: BOR/MOL 15. Bod Gaya Island, Tun Sakaran Marine Park, Semporna, Sabah: BOR/MOL 4729. Gomantong limestone hill, Sabah: BOR/MOL 3320. Balambangan Island, Sabah (07°14.00'N, 116°52.00'E): BOR/MOL 3684. Kok simpul, Pulau Balambangan, Kudat Province, Sabah (07°13.03'N, 116 °53.14'E): BOR/MOL 1445. S end Batu Sireh, Pulau Balambangan, Kudat Province, Sabah (07°12.29'N, 116°51.30'E): BOR/MOL 1439. Segama valley, limestone hill on N bank Segama River, near bridge of road Sandakan to Lahad Datu, Tawau province, Sabah (05°06.10'N, 118°13.12'E): JJV 7495. Materis, Kinabatangan, Sabah (05°31.38'N, 118°01.02'E): BOR/MOL 11820, BOR/MOL 11851, BOR/MOL 11910, BOR/MOL 11945. Bukit Mawas, lower Kinabatangan valley, Sabah (05°27.20'N, 118°08.67'E): BOR/MOL 1954, RMNH/MOL 5004968 (Fig. 19). Kampung, Kinabatangan, Sabah (05°30.72'N, 118°16.92'E): BOR/MOL 10901, BOR/MOL 10922. Ulu Resang, Kinabatangan, Sabah (05°30.66'N, 118°20.40'E): BOR/MOL 9284, BOR/MOL 9311, BOR/MOL 9345, BOR/MOL 9595, BOR/MOL 9610, BOR/MOL 9617. Batu Payung, Kinabatangan, Sabah (05°35.34'N, 118°19.44'E): BOR/MOL 8952, BOR/MOL 8967, BOR/MOL 8976, BOR/MOL 9003. Tomanggong Kecil, Kinabatangan, Sabah (05°30.54'N, 118°17.94'E): RMNH/MOL 152858, RMNH/MOL 152859, BOR/MOL 7473, BOR/MOL 9619, BOR/MOL 9685, BOR/MOL 9903, BOR/MOL 9943, BOR/MOL 9952, BOR/MOL 9983. Tomanggong Besar 1, Kinabatangan, Sabah (05°31.86'N, 118°18.24'E): BOR/MOL 10560, BOR/MOL 10806, BOR/MOL 11318, BOR/MOL 11361. Tomanggong Besar 2, Kinabatangan, Sabah (05°31.32'N, 118°17.88'E): BOR/MOL 10385, BOR/MOL 10411, BOR/MOL 10531, BOR/MOL 11352. “NewLocation1”, Kinabatangan, Sabah (05°27.40'N, 118°08.76'E): RMNH/MOL 5004826.

Description.

Protoconch. Colour: red. Sculpture: irregular sculptural shape to smooth. Mesh width: 1-20 µm. Teleoconch. Colour: red. First whorl: convex. Subsequent whorls: convex. Suture: clearly impressed. Shoulder: narrow. Number of whorls: 2 ¾– 3. SH: 1.00-1.33 mm. SW: 0.77-0.96 mm. SI: 1.22-1.42. Shell sculpture. Radial sculpture: absent, only weak growth lines are here and there visible. Spiral sculpture: present, appearing immediately after the protoconch, regularly arranged; ca. 8-10 spiral ribs on the first whorl, on the later whorls the sculpture is more prominent at the upper part of the whorl, weaker and flattened closer to the columellar region. Aperture. Shape: semi-elliptic to rounded, straight to slightly concave parietal side, palatal edge contiguous with the parietal side, basal side convex. AH: 0.40- 0.53 mm. AW: 0.45-0.60 mm. AI: 0.81-1.00.

Diagnosis.

Georissa bangueyensis is characterised by its clear spiral ribs at the upper part of the body whorl, similar to G. flavescens and G. nephrostoma , but the two latter species have wavy spiral ribs. Spiral sculpture on the lower whorl is weaker and less obvious closer to the columellar region. In shell sculpture, it is most similar to G. xesta , but the latter species has more densely arranged spiral sculpture (see discussion in G. xesta ).

Distribution.

Georissa bangueyensis is widely distributed in the coastal regions of northern and eastern Sabah.

Molecular analysis.

ML and Bayesian analyses of G. bangueyensis (16S: n = 6; CO1: n = 6) show that G. bangueyensis forms a monophyletic clade with 100% BS and 100% PP, and is sister to G. flavescens .

Discussion.

Thompson and Dance (1983) questioned the validity G. bangueyensis as a proper species based on a limited number of specimens. We propose that G. bangueyensis is a proper species with distinct characteristics, as compared to G. xesta .