Trichelix Ancey, 1887

Sutcharit, Chirasak, Inkhavilay, Khamla & Panha, Somsak, 2020, Taxonomic note on Trichelix horrida (Pfeiffer, 1863) from Laos, with a type catalogue of Moellendorffia, Trichelix, and Moellendorffiella (Heterobranchia, Camaenidae), ZooKeys 952, pp. 65-93 : 65

Genus Trichelix Ancey, 1887

Trichelix Ancey 1887: 64. Schileyko 2003: 1513.

Helix (Trihelix) : Pilsbry 1890: 9 (incorrect subsequent spelling). Pilsbry 1895: 289.

Moellendorffia ( Trihelix [sic]): Pilsbry 1905: 65.

Moellendorffia (Trichelix) : Zilch 1960: 612.

Type species.

Helix horrida Pfeiffer, 1863; by original designation.

Description.

Shell small to medium-sized, flattened to concave, rather thin, umbilicate, and corneous to brownish. Spire shrunken; embryonic shell nearly smooth; following whorls granulated and with short to long periostracal hairs arranged in oblique rows along the lines of growth. Last whorl rounded and descending anteriorly. Aperture ventral or subvertical; trigonal or subcircular; with strong or weak barriers inside the aperture at upper periphery and below periphery, and externally marked with strong to weak longitudinal furrows. Peristome expanded and continuous or discontinuous; parietal callus thin or thickened and little elevated.

Genitalia typical of camaenids, without either dart apparatus or accessory glands. Penis and epiphallus long, penial verge present, and flagellum short. Internal wall of penis and vagina with longitudinal pilasters.

Radular teeth arranged in V-shaped rows; central and lateral teeth triangular.

Remarks.

The genus is currently comprised of six nominal species ( Schileyko 2003; Minato 2011). Two species occur in northern Laos and southern China (Fig. 3 ), viz. T. horrida and T. biscalpta (Heude, 1885), and one has been recorded from Taiwan, viz. T. hiraseana (Pilsbry, 1905). Three species occur on the Amami Islands, Central Ryukyu Islands, Japan, viz. T. eucharista (Pilsbry, 1901), T. diminuta (Pilsbry & Hirase, 1905) and T. tokunoensis (Pilsbry & Hirase, 1905).

Figures

Figure 3. Approximate geographical position of the type locality of all nominal species of the genera Moellendorffia (circle), Trichelix (square), and Moellendorffiella (triangle). The numbers indicated correspond to the nominal species listed in the catalogue of the type specimen.