Ditropopsis constricta 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 : 15-16

Taxon classification Animalia Architaenioglossa Cyclophoridae

Ditropopsis constricta Vermeulen, Liew & Schilthuizen sp. n. Figure 13

Ditropopsis constricta nomen nudum, Clements et al. 2008: 2761-2762.

Ditropopsis sp. "BO-01 [= V8027]", Schilthuizen et al. 2002: 257-258; Schilthuizen et al. 2002b: 37, 41.

Holotype. Malaysia, Sabah, Interior Province , Sepulut valley, Gua Sanaron ( RMNH.5003919 ).

Examined material from Sabah.

Interior Province. Crocker Range N.P., near the km 59 marker on the road Kota Kinabalu-Tambunan (leg. J.J. Vermeulen, V 1183). Sepulut valley, Batu Temurung (leg. J.J. Vermeulen, V 8027); Gua Pungiton (leg. J.J. Vermeulen & M. Schilthuizen, V 8077); Gua Sanaron (leg. J.J. Vermeulen & M. Schilthuizen, V 7650). Sandakan Province. Danum Valley Field Centre (c. 60 km West of Lahad Datu): Clive Marsh grid W11/N0 (leg. Noel Tawatao, V 13483; leg. M. Schilthuizen, BOR/MOL 314, BOR/MOL 316). Tawau Province. Batu Baturong c. 50 km W.S.W. of Lahad Datu (leg. J.J. Vermeulen & H. Duistermaat, V 1850).

Description.

Shell very small, rather thick, somewhat translucent, off-white to pale greenish yellow. Surface shiny. Spire rather low-conical, apex slightly protruding, slightly oblique. Sculpture. Radial sculpture: fine growth lines, locally grading into fine, densely placed riblets. Spiral sculpture on the last whorl: 4-7 rather inconspicuous to very distinct cords: 1 supraperipheral and 1 peripheral, about equally wide, 1 basal and 1-4 umbilical, if fewer than 4 umbilicals then those closest to the basal cord absent; next to these a fine spiral striation on the lower surface. Sculpture continuing up to the peristome, but close to the peristome distorted and partly obliterated by densely placed, low radial riblets in fully adult shells. Aperture. Peristome simple, not expanded, distinctly constricted in fully adult shells, parietal side slightly detached from the penultimate whorl in fully adult shells, basal side slightly angular but not drawn out. Dimensions. Height 1.4-1.6 mm; width 1.8-2.1 mm; h/w 0.78-0.83; umbilicus measured over the basal spiral cord 31-32% of the shell width; number of whorls 3 7/8-4; height aperture 0.5-0.7 mm; width aperture 0.5-0.75 mm.

Habitat in Sabah and distribution.

Primary and secondary forest. Predominantly on limestone soil, scattered records from sandstone, 0-1000 m alt. Sabah: South and S.E. part. Also in Sarawak; Brunei; Kalimantan (East part). Endemic to Borneo.

Cross diagnosis.

Differs from Ditropopsis koperbergi by the constricted aperture, with a distinct radial sculpture. Juvenile shells of Ditropopsis constricta , without a fully grown aperture, have lower conical shells than Ditropopsis koperbergi , with a wider umbilicus.

Remarks.

The drawn specimen has relatively thick spiral cords, specimens with thinner cords occur.

Etymology.

The name refers to the constricted peristome.