Geotrochus kinabaluensis (E.A. Smith, 1895)

Vermeulen, Jaap J., Liew, Thor-Seng & Schilthuizen, Menno, 2015, Additions to the knowledge of the land snails of Sabah (Malaysia, Borneo), including 48 new species, ZooKeys 531, pp. 1-139 : 102-103

Taxon classification Animalia Stylommatophora Trochomorphidae

Geotrochus kinabaluensis (E.A. Smith, 1895) Figure 84

Trochonanina kinabaluensis E.A. Smith, 1895: 105. Type from Malaysia, Sabah, Mount Kinabalu.

Trochonanina kinabaluensis E.A. Smith var. pallida E.A. Smith, 1895: 106. Type from Malaysia, Sabah, Mount Kinabalu.

Examined material from Sabah.

Interior Province. Crocker Range N.P., West of the km 10 marker on the road Tambunan-Ranau, Mahua Waterfall (leg. Suhaili, BOR/MOL 3372). West Coast Province. Kinabalu N.P., Poring Hot Springs, leg. M. Schilthuizen & P. Koomen, BOR/MOL 2933); Sayap-Nunuhon trail at 1152 m (leg. T.S. Liew, Dominik, J. Lapidin & Jasilin, BOR/MOL 4025); Serinsim-Nombuyokon trail at 5.6-6 km (leg. T.S. Liew, BOR/MOL 4026); Kiau-Spurs route at 2800 m (leg. T.S. Liew, J. Lapidin & Safrie, BOR/MOL 4027).

Description.

Shell medium-sized, rather thin, opaque, brown, sometimes a slightly paler brown just below the suture, periphery pale brown to dull white; shell low-conical with approx. flat sides, apex not or hardly protruding. Surface with a silky luster above the periphery, shiny below. Whorls: slightly convex; suture impressed in the inner whorls, not so in the outer, coinciding with the periphery; last whorl acutely angular, moderately compressed at the periphery, slightly convex below the periphery. Protoconch c. 2 1/8 whorls, smooth. Teleoconch. Radial sculpture: above and below the periphery scattered inconspicuous growth lines, locally grading into inconspicuous riblets; next to this a very fine (just visible at 40 times magnification) radial wrinkling of the shell surface is locally present. Spiral sculpture: last whorl with a sharp, slightly pinched peripheral ridge; start of fifth whorl with 15-17 somewhat spaced, low and thin spiral threads, the 2-5 threads close to the periphery slightly more distinct, the others inconspicuous; no spiral sculpture below the periphery. Umbilicus closed. Peristome thickened and reflexed, basal edge most strongly curved towards the columellar side, approx. straight or slightly concave towards the periphery. Dimensions: Height 7.4-10.0 mm; width 17.6-24.5 mm; h/w 0.41-0.42; peripheral keel of the last whorl at 0.40-0.45 of the shell height, measured from the apex; diameters of the first 4 whorls 1.5-1.6 mm, 2.4-2.6 mm, 3.4-4.6 mm, 5.8-6.5 mm respectively; number of whorls 6 1/2-6 3/4, height aperture 4.0-5.5 mm; width aperture 9.0-13.0 mm.

Habitat in Sabah and distribution.

Primary and secondary forest on sandstone and shale bedrock, 600-2800 m alt. Lives on decaying wood. Sabah: Mount Kinabalu, Crocker Range. Endemic to Sabah.

Cross diagnosis.

See under Geotrochus labuanensis . The limited material seen of Geotrochus kinabaluensis suggests that the shells are usually higher and wider than those of Geotrochus labuanensis , and that the aperture is usually larger.

Remarks.

The exact morphology of a very fine radial wrinkling of the supra-peripheral part of the shell needs to be investigated.

Geotrochus kinabaluensis is a submontane species, contrary to Geotrochus labuanensis .