A new cyprinid species, Placocheilus dulongensis, from the upper Irrawaddy system in northwestern Yunnan, China

A new species of the cyprinid genus Placocheilus Wu 1977, is described from the Dulong River drainage (in the upper reach of the Irrawaddy River), northwestern Yunnan Province (China). Placocheilus dulongensis sp. nov. can be distinguished from the other three congeners, namely P. caudofasciatus, P. robustus and P. cryptonemus, by the following combination of characters: no semicircular black mark on the middle of each caudal fin lobe; no blackish band across the dorsal fin; one pair of rostral barbels and one pair of maxillary barbels; 39-40 perforated lateral line scales. Osteological characters, such as the shape of the second infraorbital, preoperculum, and the vertical plate of the urohyal were observed in a cleared and stained skeletal specimen. A simplified key to the genus Placocheilus is provided based on the comparisons among the four species.