Geotrochus subscalaris Vermeulen, Liew & Schilthuizen

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 : 111

Taxon classification Animalia Stylommatophora Trochomorphidae

Geotrochus subscalaris Vermeulen, Liew & Schilthuizen sp. n. Figure 91

Geotrochus heraclea (not of E.A. Smith, 1895) Solem, 1964: 27.

Holotype. Malaysia, Sabah, Sandakan Province, Kinabatangan valley , Batu Pangi ( RMNH.5003931 ).

Examined material from Sabah.

Sandakan Province. Kinabatangan valley, Batu Mawas (leg. T.S. Liew & M. Schilthuizen, BOR/MOL 1956, BOR/MOL 2251, BOR/MOL 1991); Batu Materis (leg. M. Schilthuizen, BOR/MOL 2430, BOR/MOL 2426); Batu Keruak (leg. T.S. Liew & B. Elahan, BOR/MOL 1847); Batu Pangi (leg. J.J. Vermeulen & M. Schilthuizen, V 9634, BOR/MOL 2421); Batu Tai (not Bod Tai) near Gomantong (leg. J.J. Vermeulen & M. Schilthuizen, V 9597); Batu Tomanggong Besar (leg. M. Schilthuizen, BOR/MOL 2428, BOR/MOL 2429; leg. M. Schilthuizen, A. van Til & B. Elahan, BOR/MOL 2973; leg. T.S. Liew & B. Elahan, BOR/MOL 2284); Batu Tomanggong Kecil (leg. M. Salverda & H. van Oosten, BOR/MOL 2427); Batu Tulug (Batu Putih) along road Lahad Datu-Sandakan, North of bridge over Kinabatangan River (leg. J.J. Vermeulen & H. Duistermaat, V 1490); Gomantong Hill 30 km South of Sandakan (leg. J.J. Vermeulen & H. Duistermaat, V 1627; leg. M. Schilthuizen, BOR/MOL 894; leg. T.S. Liew & J.P. King, BOR/MOL 3668); Tandu Batu (leg. J.J. Vermeulen & M. Schilthuizen, V 9626); Unnamed hill near Sukau Police Station (leg. T.S. Liew & B. Elahan, BOR/MOL 2220). Segama valley, North end of limestone ridge on East bank Tabin River (leg. J.J. Vermeulen & M. Schilthuizen, V 7763). Tawai Mountains near Telupid (leg. J.J. Vermeulen, V 1259). Tawau Province. Batu Baturong c. 50 km W.S.W. of Lahad Datu (leg. J.J. Vermeulen & H. Duistermaat, V 1852). Danum Valley (leg. H.A. Rutjes, BOR/MOL 888, BOR/MOL 2936; leg. M. Schilthuizen, BOR/MOL 2934); Gua Madai c. 40 km S.S.W. of Lahad Datu (leg. J.J. Vermeulen & H. Duistermaat, V 1741). Segama valley, hill N.W. of crossing road Sandakan-Lahad Datu with the Segama River (leg. J.J. Vermeulen & H. Duistermaat, V 1657); ‘Kirk’s Cave’ 8 km North of Lahad Datu (leg. J.J. Vermeulen, V 1253); Sabahmas Cave (leg. J.J. Vermeulen, V 7469, BOR/MOL 897). Tabin Wildlife Reserve (leg. T. Kimsin & H.N. Chai, BOR/MOL 898). Semporna area, Segarong Hills, Batu Tengar, 25 km E.S.E. Of Kunak (leg. J.J. Vermeulen & H. Duistermaat, V 1816); Bukit Pababola, 25 km E.S.E. of Kunak (leg. J.J. Vermeulen & H. Duistermaat, V 1780).

Description.

Shell rather small, rather thin, about opaque, yellowish to pale brown, moderately low-conical with slightly concave to slightly convex sides; apex slightly to moderately protruding. Surface with a silky luster. Whorls: Apical whorls moderately convex, outer approx. flat to slightly convex; suture impressed, between the outer 4-5 whorls slightly below the periphery; last whorl acutely angular, compressed at the periphery, rounded below the periphery. Protoconch 2 1/8-2 1/4 whorls, smooth. Teleoconch. Radial sculpture: above the periphery some growth lines, locally grading into inconspicuous riblets; below the periphery indistinct growth lines only. Spiral sculpture: last whorl with a sharp, pinched peripheral keel; start of fifth whorl with 6-10 thin, widely spaced spiral threads: Usually 1-2 (slightly) more distinct close to the periphery, as well as 5-10 inconspicuous above these; no spiral sculpture below the periphery. Umbilicus closed. Peristome thickened and reflexed. Dimensions: Height 6.2-7.3 mm; width 11-13.0 mm, h/w 0.52-0.59; diameters of the first 4 whorls 1.1-1.4 mm, 1.9-2.4 mm, 2.7-3.6 mm, 4.0-4.8 mm respectively; number of whorls 6 1/4-8, height aperture 3.2-4.0 mm; width aperture 6.0-7.2 mm.

Habitat in Sabah and distribution.

Primary and secondary forest and more degraded vegetation types on limestone soil, up to 200 m alt. Sabah: East coast. Endemic to Sabah.

Cross diagnosis.

Most similar to Geotrochus whiteheadi , differs by the suture which is situated slightly below the periphery in the outer whorls.

Etymology.

The name refers to the slightly protruding peripheral keel, creating a small notch in between the whorls in lateral view [sub-scalaris (L) = a little resembling a ladder].