Pseudochazara williamsi (Romei, 1927), the nevada grayling, is a species of butterfly in the family Nymphalidae.

Iberian Peninsula, Spain) were described as subspecies of Pseudochazara hippolyte (Esper, 1784) (an Asian taxon).

In Pseudochazara the drawings of underside of the hind wings is very variable, result of an important phenotypic plasticity, due to its ability to change the phenotype in order to obtain a certain degree of mimetism required for camouflage with the terrain of its environment to mimic the environment where it lives.

These ecological forms have no taxonomic rank in modern biological classification, therefore without taxonomical or nomenclatural significance, since there is no solid foundations to justify their subspecific validity.

The updated distribution and a morphological study (taxonomy) of P. williamsi can be seen in Gil-T. (2016, 2017).