Dyakia chlorosoma 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 : 25-27

Taxon classification Animalia Stylommatophora Ariophantidae

Dyakia chlorosoma Vermeulen, Liew & Schilthuizen sp. n. Figure 22

Holotype.

Malaysia, Sabah, West Coast Province, Crocker Range N.P., Ulu Kimanis, along Keningau-Kimanis road (BOR/MOL 1364).

Examined material from Sabah.

West Coast Province. Crocker Range N.P., Ulu Kimanis, along Keningau-Kimanis road (leg. M. Schilthuizen, BOR/MOL 1363, BOR/MOL 1364), (leg. M. Schilthuizen & A.S. Cabanban, BOR/MOL 3006). Kinabalu N.P., Headquarters area, Liwagu Trail (leg. M. Schilthuizen, BOR/MOL 1362). Gunung Trusmadi slopes (leg. M. Schilthuizen & P. Koomen, BOR/MOL 919).

Description.

Shell medium-sized, very thin, translucent, pale yellowish green, conical with slightly concave (juveniles) to slightly convex (adults) sides; apex narrowly rounded. Surface glossy. Whorls: top whorls moderately convex, outer whorls flat above and convex below the periphery, periphery pinched and sharply keeled. Protoconch sculpture: a few flat radial folds, no other sculpture. Teleoconch, radial sculpture: first whorls slightly crenellated immediately below the suture, all whorls with more or less regularly spaced, slightly raised, weak growth lines, shell surface, particularly on the last whorl, distinctly undulated following the growth lines. Spiral sculpture absent, some shells with a inconspicuous spiral undulation on the last whorl. Peristome not reflected, not drawn out into a spur at the periphery. Umbilicus closed. Dimensions: Height up to 14 mm; width up to 32 mm; diameter of the first three whorls 1.9-2.1 mm, 3.5-4 mm, 8.0-8.3 mm respectively; number of whorls up to c. 4, height aperture up to 10.5 mm; width aperture up to 14.0 mm. Animal (pale) green including the tentacles, shining through the shell a bright green.

Habitat in Sabah and distribution.

Primary forest on sandstone bedrock. Alt. 1200-1500 m. Sabah: Crocker Range, Mount Kinabalu, Mount Trusmadi. Endemic to Sabah.

Cross diagnosis.

Very similar to Dyakia moluensis Godwin Austen, 1891, the shell differs by being very thin, by having a somewhat higher spire, and a markedly undulate upper surface, by absence of any colour markings, and by absence of a fine, somewhat spaced spiral striation on the upper and lower surface. For comparison, we also provide illustrations of Dyakia moluensis (fig. 23).

Adult shells of Rhinocochlis nasuta (Metcalfe, 1851) differ by having the palatal side of the peristome drawn out into a tapering, slightly backwards curved beak. Juvenile shells without the beak are very similar to Dyakia chlorosoma , but differ by the presence of a fine, somewhat spaced, spiral striation. The animal of Rhinocochlis nasuta is green, with somewhat yellowish to orange red tentacles.

Etymology.

The name refers to the green body of the living animal [chloros (Gr.) = green; soma (Gr.) = body].