Pseudexostoma

Pseudexostoma is a genus of fish in the family Sisoridae endemic to China. These species are restricted to the upper Salween (Nujiang River) and one upper branch of the Irrawaddy (Dayinjiang River) in China. P. brachysoma is known only from the middle and lower Nujiang River. P. yunnanensis is only known from the upper Dayinjiang. These rivers were once connected, but are now separated. Also, the environment and temperature of the Nujiang River became greatly different between the northern and southern areas, leading to speciation.

==Taxonomy== Glyptosternum yunnanesis was first described in 1935. However, due to its unique teeth, a separate genus Pseudexostoma was erected in 1979 for this species. The same year, a subspecies of P. yunnanensis was described, P. y. brachysoma. However, it has become apparent that these two groups represent different species. Also, a third species, P. longipterus, was described in 2007. Results obtained by Yang et al., 2016 showed that P. longipterus cannot be distinguished from P. brachysoma from either morphological or molecular analyses and that the former name should thus be considered a junior synonym of the latter.