Also, the environment and temperature of the Nujiang River became greatly different between the northern and southern areas, leading to speciation.

However, due to its unique teeth, a separate genus Pseudexostoma was erected in 1979 for this species.

[2] 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.

[1] There are currently three recognized species in this genus: These species have a continuous groove behind the lip, gill openings not extending onto the underside, heterodont dentition in both jaws with outer teeth shovel-shaped and sparsely arranged in one or two rows and inner teeth conical and numerous, the tooth patches separated in upper jaw, and 16–18 branched pectoral rays.

The teeth are embedded in the skin, shovel-shaped, with the tips exposed and arranged in irregular rows.

P. yunnanensis also has more pelvic fin rays (5 vs. 3–4), a shorter adipose fin base, a deeper and longer caudal peduncle, more teeth in the premaxillary tooth band (18–22 vs. 16–18) that are divided into two partially connected patches instead of two isolated patches.