Trochomorpha trachus 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 : 95-96

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].