Wednesday 12 July 2017

Aenigmatoconcha clivicola: A new species of Helicarionid Land Snail from northeastern Thailand.

Helicarionid Land Snails of the Subfamily Durgellinae are found on limestone hills across South China and Southeast Asia. There are currently two described genera in the group, with Sophina found in southern Myanmar and Chalepotaxis found across southern China and Taiwan. This disjunctive distribution would seem to imply the group has diverged through allopatric speciation (i.e. the different groups have become separated from one-another geographically, then become reproductively isolated through genetic drift), however it is equally likely to be due to poor sampling, which is to say the groups could quite possibly be present together across much of their range but not have been found to date.

In a paper published in the Raffles Bulletin of Zoology on 7 June 2017, Chanidaporn Tumpeesuwan, also of the Department of Biology at Mahasarakham University, and Sakboworn Tumpeesuwan, also of the Department of Biology and of the Palaeontological Research and Education Centre at Mahasarakham University describe a new species of Durgelline Snail from Loei Province in northeastern Thailand.

The new species is deemed sufficiently different from any previously described species to be given a new genus, Aenigmatoconcha, meaning ‘riddle-shell’, and given the specific name clivicola, meaning ‘dweller on the side of a hill’. The species has a flattened shell 7.69–9.89 mm in height and 15.40–18.62 mm in width, with 5¼–5½ whorls when fully grown and a large aperture. The shell is glassy and pale brown in colour, while the foot is darker brown. 

Aenigmatoconcha clivicola, in natural habitat. Kitti Tanmuangpak in Tumpeesuwan & Tumpeesuwan (2017).

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