Taxon classification Animalia Stylommatophora Trochomorphidae

Trochomorpha trachus Vermeulen, Liew & Schilthuizen sp. n. Figure 78

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.5003928).

Examined material from Sabah.

West Coast Province, Crocker Range N.P., near the km 54 marker on the road Kota Kinabalu-Tambunan, Gunung Mas (leg. M. Schilthuizen, BOR/MOL 2959).

Description .

Shell rather small, thin, opaque, reddish brown with darker brown or whitish streaks following growth lines, slightly paler brown with similar darker streaks below the suture, conical with flat sides; apex not protruding. Surface dull or slightly shiny above the periphery, glossy below. Whorls somewhat convex, outer whorls slightly shouldered; suture impressed, coinciding with the periphery; last whorl distinctly angular and slightly compressed at the periphery, moderately rounded below the periphery. Protoconch (absent in available material). Teleoconch. Radial sculpture: above the periphery irregularly spaced growth lines, developing into locally coarse, irregular wrinkling on the outer whorls, particularly below the suture; below the periphery indistinct growth lines only. Spiral sculpture: last whorl with a peripheral thread; start of fifth whorl above the periphery with 8-9 spiral threads: 3-4 coarse, high and rather narrow threads, with c. 5 minor threads interspersed; all threads highest and most distinct over the raised radial sculpture, low or interrupted in between, at irregular intervals, and with a somewhat erose and locally incised crest; below the periphery a few traces of densely placed, shallow spiral grooves. Umbilicus closed. Peristome not thickened, nor reflexed (see remarks, below). Dimensions: Height c. 8.5 mm; width c. 12.5 mm, h/w c. 0.66; estimated diameters of the first 4 whorls c. 1.2 mm, c. 2.3 mm, c. 4.0 mm, c. 6 mm respectively; number of whorls c. 5 3/4, height aperture c. 4 mm; width aperture c. 7 mm.

Habitat in Sabah and distribution.

Mixed montane forest, c. 1400 m alt. Sabah: Crocker Range only. Endemic to Sabah.

Cross diagnosis.

Uniquely identified by the very coarse, at irregular intervals interrupted spiral sculpture.

Remarks.

The material seen is probably sub-adult, and has the apex damaged. The description of the apex and the peristome will need amendation once more material becomes available.

Etymology.

The name refers to the shell surface [trachus (Gr.) = rough].