Taphrenalla zemia Pholyotha & Sutcharit & Tongkerd & Jeratthitikul & Panha 2021, sp. nov.

Taphrenalla zemia Pholyotha & Panha, sp. nov.

(figs 1, 3, 13B, 14C, table 6)

Type material examined. Holotype: CUMZ 7213 (fig. 13B). Paratypes. Same data as holotype: CUMZ 7214 (25 shells and 30 specimens in ethanol), NHMUK (two shells), and SMF (two shells).

Other material examined. Tham Pha Sua Bureau of Monks, Mueang District, Phang-nga (8°28’30.9”N 98°32’20.8”E): CUMZ 7215 (five specimens in ethanol). Wat Tham Bang Toei, Mueang District, Phang-nga (8°27’47.9”N 98°34’11.6”E): CUMZ 7216 (five specimens in ethanol).

Type locality. Wat Khiriwong, Thap Put District, Phang-nga, Thailand (8°31’53.2”N 98°34’41.4”E).

Etymology. The specific epithet is from the Greek word ‘ zemia ’ meaning ‘loss’, which referrs to the shell being without radial grooves on the upper surface.

Diagnosis. Shell moderate to large-sized, shallowly impressed suture, and without radial groove. Epiphallic caecum straight. Dart apparatus located on vagina.

Description

Shell (fig. 13B). Shell globosely depressed, moderate to nearly large (width up to 21.3 mm; height up to 11.9 mm) and yellowish-brown. Whorls 5–6; suture shallowly impressed. Upper shell surface smooth without radial grooves. Spire moderately elevated; apex raised with a spire angle of about 137–151°. Last whorl slightly shouldered and almost rounded periphery. Aperture lip simple; umbilicus narrowly opened.

Genital organs (fig. 14C). Atrium long. Penis slender tube and slightly longer than vagina. Epiphallus cylindrical tube, nearly one and a half times total penis length. Epiphallic caecum short, and attached with penial retractor muscle. Flagellum large and slender tube. Vas deferens thin tube connected between distal end of epiphallus and free oviduct. Vagina long and cylindrical-shaped. Dart apparatus located near proximal vagina away from penis joining to atrium.

External features (fig. 3). Animal dark gray in body colour with three pale milky yellow stripes running from head to caudal horn. One stripe at middle of the body and two stripes close to foot sole.

Remarks. Taphrenalla zemia sp. nov. is distinguished from all other Taphrenalla species by the shell having a shallowly impressed suture without a subsutural band and no radial grooves on shell sculpture. Although we surveyed three localities during the wet season, only juvenile specimens were found for the examination and illustrated herein.