Ctenophorahunanensis sp. nov. (Bacillariophyta) from the Yongle River in Hunan Province, China.

A new species, Ctenophorahunanensis Bing Liu & Rioual, sp. nov., found in the Yongle River, a tributary of the Xiang River (Hunan Province, southern China) is described on the basis of morphological observations made under light and scanning electron microscopes. Ctenophorahunanensis is distinguished from other Ctenophora taxa by a unique combination of characters that includes its lanceolate valve outline with rostrate apices, sternum gradually becoming wider from valve apices to center, and a greater valve width than the other members of the genus. Ctenophorahunanensis inhabits the epilithic community in the headwaters of a freshwater river. Many abnormal valves of C.hunanensis were observed in the samples investigated and the most frequent morphological abnormalities consisted in a lack of symmetry relative to the apical axis caused by a unilateral incising in the middle part of the valve.