21 Opeas filiforme von Möllendorff, 1894

Fig. 12 A – C, Table 1

Opeas filiforme von Möllendorff, 1894: 151, pl. 16, fig. 11. Type locality: Golf von Siam: Samui-Inseln [Samui Island, Suratthani Province, Thailand]. Pilsbry 1906: 161, pl. 19, fig. 22. Zilch 1973: 120.

Prosopeas filiforme — Panha 1998: 32.

Type specimens.

Lectotype SMF 227532 (Fig. 12 A) von Möllendorff ex. C. Roebelen from Gulf von Siam: Samui-Inseln, designated in Zilch (1973: 120) . Paralectotype s SMF 145657 / 7 (7 shells), SMF 227533 / 7 (7 shells).

Other material.

Phra (Buddha) Cave, Tanintharyi Region, Myanmar (11 ° 14 ' 01.5 " N, 99 ° 10 ' 42.8 " E): CUMZ 13074 (15 shells; Fig. 12 B, C).

Description.

Shell slender and conical, translucent, whitish colour, and with 7 ½ – 8 whorls. Apex rounded; protoconch ~ 2 whorls, rounded and smooth surface; subsequent whorls generally nearly smooth with fine growth lines. Spire gradually and cylindrically tapering and largely turreted; whorls flatly convex and last whorl largest; suture deep and weakly crenulated. Aperture oblong; peristome thin; columella straight; columellar margin slightly expanded. Umbilicus narrowly opened to closed.

Distribution.

This species occurs in peninsular Thailand and is newly recorded from the Tanintharyi Region, southern Myanmar.

Remarks.

New discovered of this species were found in Tanintharyi, which borders the type locality of Thailand. The type specimen (Fig. 12 A) possesses less turreted and more convex whorls than our specimens; however, this differentiation is herein considered an intraspecific variation. Compared to O. innocens Preston, 1910 from Mawlamyine, O. filiforme from Tanintharyi can generally be differentiated by its slender and more attenuated shell, slightly convex whorls, and turreted spire. However, a comprehensive examination of O. innocens specimens from the type locality is necessary to confirm this distinction.