Geotrochus meristotrochus 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 : 111-113

Taxon classification Animalia Stylommatophora Trochomorphidae

Geotrochus meristotrochus Vermeulen, Liew & Schilthuizen sp. n. Figure 92

Holotype. Malaysia, Sabah, Interior Province , Sepulut valley , Batu Punggul (leg. J.J. Vermeulen, RMNH.5003932 ).

Examined material from Sabah.

Interior Province. Upper Padas valley, Long Pa Sia (leg. T.S. Liew & Meckson, BOR/MOL 4343). Crocker Range N.P., near the km 59 marker on the road Kota Kinabalu-Tambunan (leg. J.J. Vermeulen, V 1186); West of the km 10 marker on the road Tambunan-Ranau, Mahua Waterfall (leg. J.J. Vermeulen & M. Schilthuizen, V 9743; leg. J. Schilthuizen, BOR/MOL 896; leg. M. Schilthuizen, BOR/MOL 2420, BOR/MOL 2423, BOR/MOL 2424, BOR/MOL 3143, BOR/MOL 3345). Gunung Trusmadi slopes, Gua Loloposon (leg. J.J. Vermeulen, V 13236). Pinangah valley, Batu Urun (= Bukit Sinobang) (leg. J.J. Vermeulen, V 8008, V 1163, BOR/MOL 891); Pun Batu c. 30 km West of Sepulut (leg. J.J. Vermeulen, V 1302); Batu Punggul (leg. J.J. Vermeulen, V 1979; leg. T.S. Liew, M. Schilthuizen & S. Chiba, BOR/MOL 4317); Batu Pungiton (leg. M. Schilthuizen, BOR/MOL 890); Batu Temurung (leg. J.J. Vermeulen, V 8054, BOR/MOL 892; leg. M. Schilthuizen, BOR/MOL 893); Gua Sanaron (leg. J.J. Vermeulen & M. Schilthuizen, V 8073; leg. T.S. Liew, M. Schilthuizen & S. Chiba, BOR/MOL 4280; leg. M. Schilthuizen, BOR/MOL 887); Kampung Labang (leg. J.J. Vermeulen & M. Schilthuizen, V 7727, BOR/MOL 895). Sandakan Province. Beluran, Meliau Range (leg. T.S. Liew, M. Schilthuizen & A. van Til, BOR/MOL 3207, BOR/MOL 3208, BOR/MOL 3209, BOR/MOL 3210). Tawau Province. Batu Baturong, North slope (leg. J.J. Vermeulen, V 7603). Segama valley, limestone hill on North bank Segama River, near bridge of road Sandakan to Lahad Datu (leg. J.J. Vermeulen, V 7517). Tawau Hills Park (leg. J.P. King, BOR/MOL 2425; leg. T.S. Liew, J.J. Vermeulen & M. Schilthuizen, BOR/MOL 4272). West Coast Province. Kinabalu N.P., Serinsim-Numbuyukon trail between 548 and 1204 m (leg. T.S. Liew, BOR/MOL 4474, BOR/MOL 4475, BOR/MOL 4477). Kota Kinabalu, Kiansom (leg. M. Schilthuizen, BOR/MOL 889, BOR/MOL 2935; leg. UMS Tropical Malacology Course participants, BOR/MOL 3481).

Description.

Shell rather small, rather thin, about opaque, yellowish to pale brown, moderately low-conical with flat to slightly convex sides; apex slightly protruding or not. Surface with a silky luster. Whorls: Apical whorls moderately convex, outer slightly convex; suture impressed, between the outer 4-5 whorls slightly below the periphery; last whorl acutely angular, slightly compressed at the periphery, rounded below the periphery. Protoconch 2 1/8-2 1/2 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, slightly pinched peripheral keel; start of fifth whorl with 6-9 thin, widely spaced spiral threads: 1-2 distinct close to the periphery, as well as 4-8 inconspicuous ones above these; no spiral sculpture below the periphery. Umbilicus closed. Peristome thickened and reflexed. Dimensions: Height 6.0-7.0 mm; width 9.3-10.8 mm; h/w 0.59-0.67; diameters of the first 4 whorls 1.0-1.4 mm, 1.8-2.2 mm, 2.7-3.4 mm, 4.0-5.0 mm respectively; number of whorls 6 3/4-7 3/8, height aperture 2.8-3.5 mm; width aperture 4.8-5.5 mm.

Habitat in Sabah and distribution.

Primary, secondary forest and abandoned agricultural land on limestone and sandstone soil, up to 1300 m alt. Sabah: West part, East coast (lower Segama River valley and further South). Endemic to Sabah.

Cross diagnosis.

Shell less wide than Geotrochus subscalaris , compare shell width and aperture width of both species. Usually, the h/w-ratio is also higher than in Geotrochus subscalaris , but here a slight overlap exists.

Etymology.

The name refers to the slightly protruding peripheral keel, creating a small notch in between the whorls in lateral view [meristos (Gr.) = divided; trokhos (Gr.) = wheel, often used for the gastropod spire].