Anceyoconcha siamensis obesula (Ancey, 1888)

Sutcharit, Chirasak, Thach, Phanara, Chhuoy, Samol, Ngor, Peng Bun, Jeratthitikul, Ekgachai, Siriwut, Warut, Srisonchai, Ruttapon, Ng, Ting Hui, Pholyotha, Arthit, Jirapatrasilp, Parin & Panha, Somsak, 2020, Annotated checklist of the land snail fauna from southern Cambodia (Mollusca, Gastropoda), ZooKeys 948, pp. 1-46 : 1

Anceyoconcha siamensis obesula (Ancey, 1888) Fig. 12B

Buliminus siamensis var. obesula Ancey, 1888: 352. Type locality: Saigon, dans le jardin du gouverneur. Wood and Gallichan 2008: 71, pl. 6, figs 6, vi.

Material examined.

Locality no. 7: CUMZ-CM027 (14 shells), CUMZ-CM028 (3 shells; Fig. 12B ). The empty shells were collected from the ground among leaf litter.

Distribution.

Known only from the type locality ( Wood and Gallichan 2008).

Remarks.

This nominal subspecies was described from “Saigon” (see Wood and Gallichan (2008: pl. 6, fig. 6) for syntype). This species has a sinistral, ovate conic shell, having 6 to 7 whorls. The whorl is convex, having a wide and impressed suture. The shell surface is nearly smooth, with thin and brownish periostracum. The last whorl has a smaller diameter than penultimate whorl, well-rounded with weak keel near aperture. The shell colour is light brownish (becomes whitish when worn) and translucent. The aperture is subovate, with expanded and whitish lip, and thin parietal callus or thickened and whitish. The columella is straight and dilated, with a rimate umbilicus.

Anceyoconcha siamensis obesula differs from the nominotypical subspecies in having a much smaller shell size (shell height ranged from 15 to 20 mm), ovate shell and lower number of whorls. For comparison, A. siamensis siamensis (see Inkhavilay et al. 2019: fig. 53d, e) has a larger and elongate conic shell (shell height ranged from 20 to 25 mm), and with a weak keel near the aperture.

Figures

Figure 12. A Ganesella perakensis (Crosse, 1879) B Anceyoconcha siamensis obesula (Ancey, 1888) comb. nov. C, D Anceyoconcha rhombostoma (Pfeiffer, 1861). A white arrowhead indicates strong peripheral keel on the last whorl, the distinguished character of this species and E, F Anceyoconcha chaudoensis (Rochebrune, 1881) comb. nov.