Aenigmatoconcha, Tumpeesuwan & Tumpeesuwan, 2017

Tumpeesuwan, Chanidaporn & Tumpeesuwan, Sakboworn, 2017, Discovery of an overlooked Helicarionid land snail (Helicarionidae: Durgellinae) from northeastern Thailand, with description of a new genus and new species, and note on radula morphology and genital system, Raffles Bulletin of Zoology 65, pp. 181-188 : 182-184

Aenigmatoconcha , new genus

Type species. Aenigmatoconcha clivicola , new species.

Diagnosis. The radula possesses similar unicuspid spatulate teeth arranged in V-shaped rows. The genitalia lack an amatorial organ and possess a large, stout penis and slender elongate epiphallus.

Etymology. “ Aenigma ” from the Latin word meaning something obscure, a riddle or mystery, and “ concha ” from the Latin word meaning snail or shell.

Remarks. The radula and genital organs form the unique characters distinguishing Aenigmatoconcha , new genus, from other morphologically close helicarionid genera.

Reference: 1 = Benson (1859a); 2 = Benson (1859b); 3 = Benson (1860); 4 = Stoliczka (1871); 5 = Blanford & Godwin-Austen (1908);

6 = Schileyko (2011); and 7 = Páll-Gergely et al., (2016)

Aenigmatoconcha differs from Sophina ( S. calias and S. schistostelis ) by the absence of an amatorial organ and the gametolytic sac with three distinct portions, including thick wall, robust tube at proximal portion and slender tube at middle portion leading to bulbous and thin walled head of distal portion. The penis is also larger and stouter than in S. calias and S. schistostelis ( Table 4 and Fig. 5 ). Aenigmatoconcha has more characters in common with Chalepotaxis , including a radula with V-shaped rows of teeth, the absence of an amatorial organ and three distinct portions of gametolytic sac ( Páll-Gergely et al., 2016), but it differs in shell characters, radula teeth without smaller upper part, and short and stout penis without penial sheath.

Figures

Fig. 5. Aenigmatoconcha clivicola, new species, genital system of paratype (NHMSU-0014) and schematic drawing. Abbreviations: ag, albumen gland; at, atrium; ep, epiphallus; erc, epiphallic retractor caecum; fo, free oviduct; gs, gametolytic sac; hd, hermaphroditic duct; p, penis; pr, penial retractor; pro, prostate gland; ut, uterus; v, vagina; vd, vas deferens. Photograph and illustration: Kitti Tanmuangpak.