Philalanka kusana (Aldrich, 1889)

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 : 51-54

Taxon classification Animalia Stylommatophora Endodontidae

Philalanka kusana (Aldrich, 1889) Figure 43

Trochomorpha kusana Aldrich, 1889: 24. Sitala kusana (Aldrich) Godwin Austen, 1891: 40. Philalanka kusana (Aldrich) Schilthuizen & Rutjes, 2001: 419-420; Schilthuizen et al. 2002: 256-258; Schilthuizen et al. 2002b: 37, 41-42; Schilthuizen and Vermeulen 2003: 96; Schilthuizen 2004: 94; Clements et al. 2008: 2762; Schilthuizen et al. 2011: 5; Schilthuizen et al. 2013: online supplementary data. Type from Indonesia, S.E. Kalimantan.

Sitala quadricarinata Gude, 1917: 315. Type from Borneo.

Philalanka kusana [Not Philalanka kusana auct. Vermeulen & Whitten, 1998: 92, 148; = Philalanka tjibodasensis (Leschke)].

Examined material from Sabah.

Interior Province. Long Pa Sia (leg. Meckson & T.S. Liew, BOR/MOL 4341). Tenom (leg. M. Schilthuizen, BOR/MOL 3359). Crocker Range N.P., Gua Laing c. 12 km North of Keningau (leg. J.J. Vermeulen, V 1115; leg. M. Schilthuizen, BOR/MOL 755); West of the km 10 marker on the road Tambunan-Ranau, Mahua Waterfall (leg. J.J. Vermeulen & M. Schilthuizen, V 9730; leg. J. Schilthuizen, BOR/MOL 763; leg. M. Schilthuizen, BOR/MOL 3140). Gunung Trusmadi slopes, Gua Loloposon (leg. J.J. Vermeulen, V 13223; leg. M. Schilthuizen & P. Koomen, BOR/MOL 760; leg. M. Suleiman & M. Schilthuizen, BOR/MOL 2401). Pinangah valley, Batu Urun (= Bukit Sinobang) (leg. J.J. Vermeulen, V 1165, V 8000; leg. M. Schilthuizen, BOR/MOL 747). Pun Batu c. 30 km West of Sepulut (leg. J.J. Vermeulen, V 1281). Sepulut valley, Batu Punggul (leg. J.J. Vermeulen, V 1984; leg. T.S. Liew, BOR/MOL 4327; leg. M. Schilthuizen, BOR/MOL 745); Batu Temurung (leg. J.J. Vermeulen, V 8045, V 8046; BOR/MOL 767, BOR/MOL 768; leg. M. Schilthuizen, BOR/MOL 746); Bukit Tinagas, East end of Batu Punggul limestone (leg. J.J. Vermeulen & M. Schilthuizen, V 7630; leg. J.J. Vermeulen, BOR/MOL 753; leg. M. Schilthuizen, BOR/MOL 740); Gua Pungiton (leg. J.J. Vermeulen & M. Schilthuizen, V 7553, V 8084, BOR/MOL 749); Gua Sanaron (leg. J.J. Vermeulen & M. Schilthuizen, V 7666; leg. M. Schilthuizen, BOR/MOL 739, BOR/MOL 744). Kudat Province. Balambangan Island, Kok Simpul (leg. J.J. Vermeulen & M. Schilthuizen, V 9531; leg. T.H. Liew, BOR/MOL 3695); Forest near Kampung Magnin (leg. M. Schilthuizen, BOR/MOL 4359, BOR/MOL 4366). Sandakan Province. Kinabatangan valley, Batu Pangi (leg. J.J. Vermeulen & M. Schilthuizen, V 9646); Batu Tomanggong Kecil (leg. J.J. Vermeulen & M. Schilthuizen, V 9689; leg. T.S. Liew, BOR/MOL 2069; leg. J.J. Vermeulen, BOR/MOL 2314); Bod Tai (leg. M. Schilthuizen, BOR/MOL 2316); Batu Tulug (Batu Putih) along road Lahad Datu-Sandakan, North of bridge over Kinabatangan River (leg. J.J. Vermeulen & H. Duistermaat, V 1484); Gomantong Hill 30 km South of Sandakan (leg. J.J. Vermeulen & H. Duistermaat, V 1618; leg. A. van Til, BOR/MOL 3279; leg. A. van Til, BOR/MOL 3280, BOR/MOL 3298; leg. M. Schilthuizen, BOR/MOL 761; leg. T.S. Liew, BOR/MOL 3657). Segama Valley, North end of limestone ridge on East bank Tabin River (leg. J.J. Vermeulen & M. Schilthuizen, V 7772); Tabin (leg. M. Schilthuizen, BOR/MOL 743; leg. H.N. Chai, BOR/MOL 751; leg. J.J. Vermeulen, BOR/MOL 766). Tawau Province. Batu Baturong c. 50 km W.S.W. of Lahad Datu (leg. J.J. Vermeulen & H. Duistermaat, V 1862); North slope (leg. J.J. Vermeulen, V 7596). Gua Madai c. 40 km S.S.W. of Lahad Datu (leg. J.J. Vermeulen & H. Duistermaat, V 1731); N.E. end (leg. J.J. Vermeulen, V 7703). Danum Valley (leg. M. Schilthuizen, BOR/MOL 748, BOR/MOL 756, BOR/MOL 757, BOR/MOL 759; leg. J.J. Vermeulen, BOR/MOL 741; leg. H.N. Chai, BOR/MOL 754; leg. H.A. Rutjes, BOR/MOL 764; leg. N. Tawatao, BOR/MOL 2318; leg. UMS students, BOR/MOL 765). Segama valley, hill N.W. of crossing road Sandakan-Lahad Datu with the Segama River (leg. J.J. Vermeulen & H. Duistermaat, V 1673); ‘Kirk’s Cave’ 8 km North of Lahad Datu (leg. J.J. Vermeulen, V 1235); limestone hill on North bank Segama River, near bridge of road Sandakan to Lahad Datu (leg. J.J. Vermeulen, V 7509); Sabahmas Cave (leg. J.J. Vermeulen, V 7465, BOR/MOL 752). Semporna area, Segarong Hills, Bukit Pababola, 25 km E.S.E. of Kunak (leg. J.J. Vermeulen & H. Duistermaat, V 1773). Tawau Hills N.P., path up to Bukit Bombalai (leg. J.J. Vermeulen, V 13153); waterfalls near Headquarters area (leg. J.J. Vermeulen, V 13198; leg. J.P. King, BOR/MOL 2315). West Coast Province. Kinabalu N.P., Poring Hot Springs, orchid Garden (leg. J.J. Vermeulen, V 13029; leg. P. Koomen, BOR/MOL 762); Serinsim-Nombuyukon trail between 458 and 542 m (leg. T.S. Liew, BOR/MOL 4214, BOR/MOL 4215). Kota Kinabalu, Kiansom Waterfall (leg. UMS students, BOR/MOL 750; leg. M. Schilthuizen, BOR/MOL 758; leg. UMS Tropical Malacology Course participants, BOR/MOL 3466).

Description.

Shell very small, thin, translucent to opaque, light brown to pale yellow-corneous to white, conical with slightly convex sides, sometimes conical-ovoid; apex rounded. Surface shiny. Whorls convex, rounded or slightly angular because of the presence of strong spiral threads, somewhat flattened below the lowermost spiral thread, sometimes somewhat flattened above the upper spiral thread. Protoconch whorls convex; sculpture: (1-)4-6(-9) inconspicuous to distinct, thin spiral threads; radial sculpture absent or some subordinate wrinkles. Teleoconch: Last whorl with (2-)3(-4) distinct, narrow spiral threads (when 2: 1 above and 1 below the periphery; when 3-4: 1 at the periphery, 1 well below, and 1-2 above), the lowermost coinciding with the suture of the penultimate whorl; between the spiral threads often (traces of) a fine, rather dense to moderately spaced spiral striation; below the lowermost spiral thread a similar moderately to widely spaced spiral striation which gradually disappears towards the umbilicus. Radial sculpture most distinct below the suture: fine growth lines, locally grading into somewhat spaced riblets. Umbilicus open, narrow. Dimensions: Height up to 3.2 mm; width up to 3.5 mm; diameters of the first four whorls 0.6-0.8 mm, 1.0-1.3 mm, 1.6-2.0 mm, 2.1-2.7 mm respectively; number of whorls up to 5 1/2; height aperture up to 1.1 mm; width aperture up to 1.6 mm.

Habitat in Sabah and distribution.

Primary and secondary forest, shrubby regrowth, rock outcrops, on sandstone and limestone soil, up to 600 m alt. (up to 1200 m alt. in Sarawak). Sabah: common, widespread. Also in Sarawak; Kalimantan. Distribution: Peninsular Malaysia; Sumatra; Eastwards to Irian Jaya.

Cross diagnosis.

Philalanka tjibodasensis (Leschke), from Java, has a comparable size and mode of coiling (diameter of the first four whorls c. 0.6 mm, 1.1 mm, 1.6 mm, 2.4 mm respectively). It differs by having flattened protoconch whorls without spiral sculpture.

Philalanka carinifera (Stoliczka), from Peninsular Malaysia, is of similar shape, but smaller (height up to 2 mm, and width up to 2.1 mm, at 5 3/8 whorls). It is also more densely coiled (diameter of the first four whorls 0.4-0.5 mm, 0.70-0.85 mm, 1.05-1.20 mm, 1.4-1.6 mm respectively).

Remarks.

Most individuals of Philalanka kusana have 3 spiral threads, but large samples usually include a small number of specimens with only 2 spiral threads. In a few samples from the Crocker Range, Kappes (unpublished report) suspects two discrete species within our concept of Philalanka kusana , based on molecular data and supported by slight differences in protoconch sculpture. We find a wide variability in protoconch sculpture, and cannot accordingly divide all material available.

Aldrich (1889) describes the shell colour as light brown. All specimens seen by us range from pale yellow-corneous to white.