Japonia anceps 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 : 18-19

Taxon classification Animalia Architaenioglossa Cyclophoridae

Japonia anceps Vermeulen, Liew & Schilthuizen sp. n. Figure 16

Holotype. Malaysia, Sabah, Interior Province , Crocker Range N.P. , Gua Laing c. 12 km North of Keningau (leg. J.J. Vermeulen, RMNH.5003957 ).

Examined material from Sabah.

Interior Province. Crocker Range N.P., Gua Laing c. 12 km North of Keningau (leg. J.J. Vermeulen, V 1104; M. Schilthuizen, BOR/MOL 200).

Description.

Shell small, rather solid, opaque, white to yellowish, with vaguely outlined pale brown radial blotches on the upper surface. Surface slightly shiny. Spire conical, top distinctly protruding, periphery sharply angular, whorls almost flat to slightly convex (in large specimens) above the periphery, slightly convex below; transition from basal to umbilical area somewhat less distinctly angular than the periphery. Whorls not channeled towards the suture. Sculpture. Radial sculpture: rather distinct, irregular growth lines, grading into similar radial riblets. Spiral sculpture on the last whorl: 1 distinct peripheral thread, 1 distinct basal thread, above the peripheral thread slight and inconspicuous spiral striation, below slightly more distinct striation, in the umbilical region still more distinct striation, grading into very fine, densely placed, thin threads; penultimate whorl with 1 distinct peripheral thread, just above the suture. Aperture subcircular, slightly angular on the palatal side. Peristome double, the inner hardly reflected, a rim which slightly protrudes from the outer; the outer peristome moderately reflected, somewhat concave. Dimensions. Height 4.7-6.2 mm; width 5.6-7.1 mm; h/w 0.84-0.88; umbilicus 0.7-1.0 mm wide, u/w 0.11-0.13; number of whorls 4 7/8-5 5/8; height aperture 2.5-2.8 mm; width aperture 2.7-3.5 mm. Periostracum without hairs.

Habitat in Sabah and distribution.

Secondary forest on limestone bedrock. Alt. c. 500 m. Sabah: Crocker Range, Laing Cave near Keningau only. Endemic to Sabah.

Cross diagnosis.

Shares the angular periphery and the whorls which are only slightly convex above and below with Japonia hyalina Vermeulen & Junau, 2007, and Japonia ditropis Vermeulen & Junau, 2007, both from Sarawak. It differs from both by its larger size (shell height 4.7-6.2 mm, versus 2.0-3.5 mm), the presence of brown blotches on on the shell, as well as by the less conspicuous spiral sculpture apart from the peripheral and basal thread.

Etymology.

The name refers to the fact that the upper and lower surface of the last whorl are about equally convex [anceps (L.) = with two faces].