Introduction
The species of Percocypris (Cyprinidae, Teleostei) are fierce predatory freshwater fishes inhabiting large rivers or lakes, in southwestern China and northern Vietnam. Members of the genus have a specific distribution pattern, that is, there is only one species or subspecies in each drainage as follows (Chinese names in brackets): Upper Yangtze River (Jinsha Jiang), Mekong River (Lancang Jiang), Salween River (Nu Jiang), Upper Pearl River (Nanpan Jiang), Red River (Yuan Jiang). The genus thus appears to be an ideal system to study how historical geologic or geographic events of the relevant drainages including the famous Three Parallel Rivers of Yunnan Protected Areas (Salween, Mekong and Upper Yangtze rivers) influenced the biogeography of freshwater fishes.