Nanhaipotamon guangdongense

Description:

The freshwater crab genus Nanhaipotamon is endemic to southern China and Taiwan. The taxonomic state of the genus is not entirely understood, as is the distribution of the known species. Many species only exist in a small range, for example N. zhuhaiense, only known from a few hill stream in the city of Zhuhai. Nanhaipotamon guangdongense was described 1997 by Dai from an unknown site in Guangdong province. 2012, Huang et al. found specimens of N. guangdongense living sympatrically with N. zhuhaiense, the first record of the species since 1997. At some sites in Zhuhai, I found N. guangdongense living in high densities (5 crabs per meter river bank) in self digged burrows next to small hill streams, often with high banks. I observed the majority of crabs staying in or close to their burrows during the day and only leaving at night but staying in close range. Nanhaipotamon species can show a great variability in carapax and claw coloration. The crabs I took photos of on a night walk at two small creeks had a more purpleish blue carapax than those found during a day visit at some other nearby streams, clearly resembling Nanhaipotamon guangdongense coloration ( Compare to: treatment.plazi.org/GgServer/html/01307731FF989932B2B5FE4...). A general revision of the genus in southern China regarding morphology/coloration is yet to be done. Although there is known almost nothing about the distribution of Nanhaipotamon species, they are sold as pets on fish markets in Guangzhou and possibly elsewhere in Guangdong. Internet research showed that there exists quite a crab owner community in southern China, with many enthusiasts collecting specimens themselves. Since they can be sold for up to 30 US Dollars a piece, collectors will not communicate the sites where they found crabs so that nobody can harvest there except them. The impact on wild populations of these crabs is basically unkown and needs to be evaluated immediatley, since crabs as pets are becoming more popular every day. Zhuhai, Guangdong.