5. Discartemon khaosokensis Panha & Burch, 1998 Figs 4H, 23, Table 1

Discartemon khaosokensis Panha & Burch, 1998: 25, 26, fig. 2. Type locality: Khao Sok National Park, Suratthani, Thailand.

Material examined.

Holotype CUMZ 6242 (Fig. 4H). Measurement: shell height 3.6 mm, shell width 11.4 mm, and with 5¾ whorls. Paratype CUMZ 6243 (4 shells).

Remarks.

This species is known only from the type locality. The shell is flattened and semi-transparent and has a concave spire with a distinct suture. Shell surface with transverse ridges that diminish below periphery, with varices present; whorls regularly coiled. Last whorl angular with a strong peripheral keel, rapidly expanded; umbilicus very wide, showing all preceding whorls. Aperture semi-ovate with narrow sinulus; peristome thin and expanded; apertural dentition of only one parietal lamella (Fig. 4H).

Discartemon khaosokensis differs from Discartemon discus in having a smaller shell, concave spire, a shell surface with tranverse ridges, a rapidly expanded last whorl with a strong peripheral keel, and a sinulus. Discartemon khaosokensis is also similar to Discartemon sykesi, but has a larger shell, a concave spire with tranverse ridges, and a rapidly expanded last whorl with a strong peripheral keel.