This rodent lives on San Lorenzo, Las Ánimas, and Salsipuedes islands in the northern Gulf of California. It inhabits dry scrub, mainly in low island areas.
South San Lorenzo specimens have a pale reddish-cinnamon wash; Burt described them as less grayish and more washed with light vinaceous-cinnamon than P. stephani. Five adults averaged 200 mm in total length and 110 mm in tail length. The adult male type measured 207 mm overall, with a 116-mm tail.
This mouse is nocturnal and inhabits dry scrub, mainly on lower parts of the islands. It feeds on seeds, sprouts, flowers, fruit, and insects, and makes burrows in spaces between large rocks. Breeding peaks in early spring and can continue into summer.
An extinction-risk assessment has not been added yet.