Perrottetia megadentata Inkhavilay & Panha

Inkhavilay, Khamla, Siriboon, Thanit, Sutcharit, Chirasak, Rowson, Ben & Panha, Somsak, 2016, The first revision of the carnivorous land snail family Streptaxidae in Laos, with description of three new species (Pulmonata, Stylommatophora, Streptaxidae), ZooKeys 589, pp. 23-53 : 37-40

Taxon classification Animalia Pulmonata Streptaxidae

Perrottetia megadentata Inkhavilay & Panha sp. n. Figs 1, 6A, B; Table 1

Type material.

Holotype CUMZ 6286 (Fig. 6A). Measurement: shell height 7.1 mm, shell width 8.2 mm, and with 6 whorls. Paratypes: CUMZ 6287 (31 shells; Fig. 6B), CUMZ 6288 (2 shells), NHMUK (2 shells), NUOL 20160251 (2 shells), SMF (2 shells).

Type locality.

The limestone outcrop at Ban Phone Can, Yommalat, Khammouan, Laos (17°31'35.6"N, 105°9'40.7"E)

Diagnosis.

The characters distinguishing Perrottetia megadentata sp. n. from Perrottetia daedaleus , Perrotettia aquilonaria , Perrottetia dugasti and Perrottetia mabillei are a single large parietal lamella, the absence of a palatal lamella absent and the presence of an infra-columellar lamella. The other four species have two parietal lamellae and a palatal lamella. Furthermore, Perrottetia dugasti and Perrotettia aquilonaria have a smooth shell, slightly depressed spire, and a bifid columellar lamella (Fig. 5A, E). Perrottetia daedaleus and Perrottetia mabillei have strong transverse ridges over the entire shell, a palatal lamella, and a bifid basal lamella, a columellar lamella is absent in Perrottetia mabillei (Fig. 5B), while one basal and one columellar lamella are present in Perrottetia daedaleus (Fig. 5C). The new species differs from Perrottetia unidentata sp. n. in its ovate shape, smooth shell surface, thicker shell, in the absence of a palatal lamella, and in having infra- and supra-columellar lamellae. The new species is superficially similar to Perrottetia dermapyrrhosa Siriboon & Panha, 2013, but is distinguished by having a single and large parietal lamella, and in the absence of a palatal lamella.

Description.

Shell oblique-ovate, white and translucent; whorls 6, spire conical, with distinct suture. Shell surface glossy with transverse ridges near suture. Embryonic shell large, about 2½ whorls, with a smooth surface; following whorls regularly coiled. Shell periphery rounded; last whorl axially deflected; two shallow and short longitudinal furrows present. Aperture subcircular, peristome continuous; parietal callus thickened; lip thickened, expanded and reflected; short sinulus present. Apertural dentition with very large and strong sinuous parietal, one large basal lamella located deep inside aperture, one small infracolumellar lamella, one large columellar lamella, and one small supracolumellar lamella. Umbilicus widely open and deep (Fig. 6A, B)

Etymology.

The specific epithet “megadentata” is derived from the Greek word “mega” meaning “large” and the Latin word “dens” meaning “tooth”. It referred to the single large parietal lamella of the new species.

Distribution.

This species is known only from the type locality in central Laos.

Remarks.

To date no living specimens have been collected.