Identity of the freshwater crab Indochinamon beieri (Pretzmann, 1966), with the description of a new genus and four new species from northeastern India (Decapoda, Brachyura, Potamidae)

The precise identity of the potamid freshwater crab, Indochinamon beieri (Pretzmann, 1966), is ascertained, diagnosed and illustrated after examining the type material from Myanmar. The diagnosis/description of the species and subsequent accounts were based on a wrongly identified and illustrated specimen, probably from Nagaland in northeastern India, which caused substantial confusion among carcinologists, who referred to different taxa as I. beieri. Two such taxa from northeastern India are referred to herein as new species of a new genus, Capitamon n. gen., i.e., C. mizoramense n. gen., n. sp. from Mizoram and C. clarki n. gen., n. sp. probably from Nagaland. Capitamon n. gen. also includes two new species, i.e., C. capitatum n. gen., n. sp. (type species) from Arunachal Pradesh and Nagaland, and C. meitei n. gen., n. sp. from Manipur. Indochinamon manipurense (Alcock, 1909) is also assigned to Capitamon n. gen. as it possesses the characteristics of the new genus. Capitamon n. gen. is thus known by five nominal species from northeastern India, while I. beieri is restricted to its type locality in Myanmar, with the previous Indian records revealed to be erroneous. With the exclusion of I. manipurense, Indochinamon Yeo & Ng, 2007, now contains 42 species. An identification key to the species of Capitamon n. gen. is provided.