Philalanka obscura 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 : 56-57

Taxon classification Animalia Stylommatophora Endodontidae

Philalanka obscura Vermeulen, Liew & Schilthuizen sp. n. Figure 45

Philalanka obscura nomen nudum, Clements et al. 2008: 2762.

Holotype. Indonesia, Kalimantan Timur, Sangkulirang Peninsula , Meweding Cave near village Tabalar Ulu ( RMNH.5003939 ).

Examined material from Sabah.

Interior Province. Upper Padas valley, Long Pasia (leg. T.S. Liew & Meckson, BOR/MOL 4350). Crocker Range N.P., Gua Laing c. 12 km North of Keningau (leg. J.J. Vermeulen, V 12721; leg. M. Schilthuizen, BOR/MOL 774); Ulu Kimanis (leg. UMS students, BOR/MOL 2329). Pinangah valley, Batu Urun (= Bukit Sinobang) (leg. J.J. Vermeulen, V 12719, BOR/MOL 3605). Pun Batu c. 30 km West of Sepulut (leg. J.J. Vermeulen, V 1280). Sepulut valley, Batu Punggul (leg. J.J. Vermeulen, V 14252); Batu Temurung (leg. J.J. Vermeulen, V 12722; leg. M. Schilthuizen, BOR/MOL 771); Bukit Tinagas, East end of Batu Punggul limestone (leg. J.J. Vermeulen & M. Schilthuizen, V 12720, BOR/MOL 772; leg. M. Schilthuizen, BOR/MOL 776); Gua Pungiton (leg. J.J. Vermeulen & M. Schilthuizen, V 12724, BOR/MOL 3604); Gua Sanaron (leg. J.J. Vermeulen & M. Schilthuizen, V 12725). Sandakan Province. Segama Valley, North end of limestone ridge on East bank Tabin River (leg. J.J. Vermeulen & M. Schilthuizen, V 7771). Tawau Province. Batu Baturong, North slope (leg. J.J. Vermeulen, V 12723). Danum Valley (leg. H.A. Rutjes, BOR/MOL 769; leg. UMS students, BOR/MOL 779); Gua Madai c. 40 km S.S.W. of Lahad Datu, NE end (leg. J.J. Vermeulen, V 7704). West Coast Province. Kinabalu N.P., Poring Hot Springs, along path to waterfall (leg. J.J. Vermeulen, V 13010; leg. M. Schilthuizen & P. Koomen, BOR/MOL 780).

Description.

Shell very small, rather thin, more or less opaque, (dark) brown, sometimes yellowish, conical with approx. flat or slightly convex sides; apex rounded. Surface about dull or with a silky luster above the periphery, glossy below. Whorls convex, approx. rounded. Protoconch whorls convex; sculpture: 9-12 inconspicuous to distinct, very fine, thin spiral threads; radial sculpture absent or some subordinate wrinkles. Teleoconch: Last whorl with a distinct spiral thread coinciding with the suture of the penultimate whorl, above this 3-4 about equally distinct threads, and in between up to 2 less distinct ones; below the lowermost thread a very fine spiral striation close to it, sometimes with up to 4 slightly coarser threads interspersed. Radial sculpture: densely placed, very fine (just visible at 40 times magnification), narrow riblets that may be inconspicuous locally. Umbilicus open, narrow. Dimensions: Height up to 2.7 mm; width up to 2.4 mm; diameters of the first four whorls 0.5-0.65 mm, 0.85-1.00 mm, 1.15-1.35 mm, 1.5-1.8 mm respectively; number of whorls up to 5 3/4; height aperture up to 0.9 mm; width aperture up to 1.3 mm.

Habitat in Sabah and distribution.

Primary and secondary forest on limestone and sandstone soil, up to 500 m alt. Sabah: scattered localities. Also in Kalimantan. Endemic to Borneo.

Cross diagnosis.

Differs from Philalanka moluensis by not having a fine spiral striation in between the spiral threads above the periphery, except for a few subordinate threads. Next to this, the shells are usually higher conical, and the spiral threads are thicker.

Etymology.

The name refers to the shell colour [obscurus (L.) = dark].