A narrow ring of dusky fur is found around the eyes, while the ears are dark brown to black, with white edges.

[2] The mouse is virtually identical in appearance to the closely related species Peromyscus sonoriensis (formerly referred to as P. maniculatus).

Although subtle differences in the fur and shape of the skull occur between the species, the considerable overlap in the appearance of individuals means even these features cannot reliably be used to distinguish them.

They occur from the Neovolcanic range through the Sierra Madre Oriental and Occidental, and across the US border into mountainous regions of southern Arizona.

[5] Unusually, they are able to tolerate very bitter cardenolide chemicals,[6] allowing them to consume relatively large quantities of monarch butterflies.