Ditropopsis trachychilus 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 : 13

Taxon classification Animalia Architaenioglossa Cyclophoridae

Ditropopsis trachychilus Vermeulen, Liew & Schilthuizen sp. n. Figure 10

Holotype. Malaysia, Sabah, West Coast Province , Crocker Range N.P. , near the km 54 marker on the road Kota Kinabalu-Tambunan , Gunung Mas (leg. J.J. Vermeulen & M. Schilthuizen, RMNH.5003918 ).

Examined material from Sabah.

West Coast Province, Kinabalu N.P., summit trail, between 2308-2775 m (leg. T.S. Liew, BOR/MOL 4121, BOR/MOL 4113); Bowen route at 3376 m (leg. T.S. Liew & Jasilin, BOR/MOL 4111); Mesilau trail between 2092-2356 m (leg. T.S. Liew, BOR/MOL 4119, BOR/MOL 4114); Kotal’s route between 2924-3048 m (leg. T.S. Liew, J. Lapidin, Safrie & Jasilin, BOR/MOL 4117, BOR/MOL 4115; leg. T.S. Liew & Jasilin, BOR/MOL 4118); Sayap-Nunuhon trail between 2640-2944 m (leg. T.S. Liew, Dominik, J. Lapidin & Jasilin, BOR/MOL 4116, BOR/MOL 4112, BOR/MOL 4120, BOR/MOL 4123, BOR/MOL 4124).

Description.

Shell very small, rather thick, hardly translucent, pale greenish. Surface shiny. Spire rather high-conical. Radial sculpture: fine growth lines, locally grading into fine, densely placed riblets. Sculpture. Spiral sculpture on the last whorl: 4 cords: 1 supraperipheral and 1 peripheral, about equally wide, 1 basal; these all rather distinct; 1 umbilical, inconspicuous and located deep inside the umbilicus; next to these a fine spiral striation on the lower surface. This sculpture continuing up to about 0.8 mm from the peristome, to be replaced by densely and irregularly placed radial riblets with a periostracal crest. Aperture. Peristome simple, not expanded, parietal side slightly detached from the penultimate whorl, basal side rounded, hardly drawn out. Dimensions. Height c. 2.3 mm; width c. 2 mm; h/w c. 1.15; umbilicus measured over the basal spiral cord c. 25 % of the shell width; number of whorls c. 4 1/8; height aperture c. 0.8 mm; width aperture c. 0.8 mm.

Habitat in Sabah and distribution.

Primary montane oak forest on sandstone bedrock, in leaf litter, sub-alpine forest on ultrabasic and granodioritic bedrock, 1300-1400 m (Crocker Range), 2000-3400 m (Mount Kinabalu) alt. Sabah: Mount Kinabalu, Crocker Range. Endemic to Sabah.

Cross diagnosis.

Similar to Ditropopsis koperbergi , but shell higher conical. The distinctive sculpture near the aperture develops only when fully adult, as in other species of the genus.

Ditropopsis gradata Quadras & Moellendorff, 1896 and Ditropopsis pusilla Quadras & Moellendorff, 1895, from the Philippines, have a similarly high spire and spiral cord distribution. Both species have a more rounded profile to the whorls.

Etymology.

The name refers to the peristome [trachus (Gr.) rough; cheilos (Gr.) = lip].