Perrottetia theobaldi (Benson, 1859)

Sian Man, Nem, Siriboon, Thanit, Lin, Aung, Sutcharit, Chirasak & Panha, Somsak, 2022, Revision of the carnivorous land snail family Streptaxidae (Stylommatophora, Achatinina) in Myanmar, with description of four new species, ZooKeys 1110, pp. 39-102 : 39

Perrottetia theobaldi (Benson, 1859)

Fig. 8

Streptaxis theobaldi Benson, 1859b: 187. Type locality: Nauclai (lat. 25°15', long. 92°30') [probably in Meghalaya State, India]. Pfeiffer 1868: 449. Hanley and Theobald 1870: 4, pl. 8, fig. 9. Nevill 1878: 3. Tryon 1885: 77, pl. 16, figs 14, 86. Blanford and Godwin-Austen 1908: 9, 10. Ramakrishna et al. 2010: 189.

Odontartemon (Perrottetia) theobaldi - Kobelt 1906: 111, 112, pl. 57, fig. 25. Kobelt 1910: 151.

Perrottetia theobaldi - Richardson 1988: 242, 243. Gittenberger et al. 2021: 74, fig. 1.

Material examined.

Syntype UMZC I.102535 (2 shells) from unknown locality. Khasi Hill: NHMUK 1888.12.4.784-786 (3 shells; Fig. 8A ) ex. Theobald collection. Siam boundary: NHMUK 1903.7.1.4005 (7 shells + 1 juvenile; Fig. 8C ) ex. Godwin-Austen collection. Burma: NHMUK 1871.9.23.143 (1 shell; Fig. 8B ). Aik Kham Cave , Taunggyi Township , Shan State, Myanmar (20°49'07.0"N, 97°13'42.0"E): CUMZ 13006 (4 shells; Fig. 8D ) .

Diagnosis.

Perrottetia theobaldi is similar to P. dugasti (Morlet, 1892) from Vietnam; however, the former species can be distinguished by having a second parietal lamella running to the main parietal lamella, thicker and less reflected peristome, subquadrangular aperture, and shallow suture. In contrast, P. dugasti has a weak second parietal lamella running to the sinulus, thinner and more reflected peristome, semi-ovate aperture, and a deeper suture with a clear bifid columellar lamella. Similarly, P. mabillei (Bavay & Dautzenberg, 1903) from Vietnam can be separated from P. theobaldi by its strong radial ridges, wide and short sinulus, basal lamella absent, bifid columellar lamellae, and deep umbilicus, while P. theobaldi has a smooth shell surface, long and narrow sinulus, strong basal lamella, columellar lamellae separated, and shallow umbilicus. Furthermore, P. theobaldi differs from the Thai species P. aquilonaria Siriboon & Panha, 2013 by having a shallow suture, narrow and long sinulus, rounded last whorl, peristome thicker and less reflected, aperture subquadrangular and columellar lamellae are separated. In contrast, P. aquilonaria possesses deep suture, shorter and wider sinulus, the last whorl shouldered, aperture subcircular, more expanded peristome, and bifid columellar lamella.

Description.

Shell sub-oblique heliciform, white, and translucent; whorls 5- 5½; spire convex with distinct suture. Shell surface glossy with transverse ridges that diminish below periphery. Embryonic shell ~ 2½ whorls with smooth surface; following whorls regularly coiled. Shell periphery rounded; last whorl axially deflected; two deep and short longitudinal furrows present. Aperture triangular with sinulus; peristome continuous, thickened, expanded, and reflected. Apertural dentition with one large and strong parietal, nearly adjoined small second parietal lamella; adjoined at right angles, one small upper palatal, one strong palatal, one strong basal, and bifid columellar lamella. Columellar lamella is sometimes absent. Umbilicus narrow (Fig. 8 ).

Distribution.

This species has been widely recorded from India to Bhutan and Myanmar ( Blanford and Godwin-Austen 1908; Ramakrishna et al. 2010; Gittenberger et al. 2021). In Myanmar, the previous record was from Bhamo, Kachin State ( Blanford and Godwin-Austin 1908) and the empty shells together with H. thebawi (Godwin-Austin, 1888) were found from Shan State in this sampling.

Remarks.

All the specimens of P. theobaldi (Fig. 8 ) showed slight differences in the apertural dentition and peristome positions, particularly the columellar and supracolumellar lamellae that are closer or almost united compared to the specimens from the Aik Kham Cave, Shan State (Fig. 8D ). However, all were collected from the same range; we place them as the same species.

Figures

Figure 8. Perrottetia theobaldi A syntype UMZC I. 102535 (no locality data) with apertural dentition B specimen NHMUK 1871.9.23.143 from Burma C specimen NHMUK 1903.7.1.4005 from Siam boundary D specimen CUMZ 13006 from Aik Kham Cave, Taunggyi, Shan State with apertural dentition.