This pocket mouse lives on the Baja California Peninsula. A study found regional differences in body size and coat texture and linked the C. arenarius group with habitats that have hot summers.
The peninsular group identified as C. arenarius in the paper is smaller than the other groups and has very soft fur. Its short spine bristles on the rump are few and inconspicuous.
The C. arenarius group is associated with interior areas of the Baja California Peninsula and areas north of the Vizcaíno Desert, where summers are hot.
An extinction-risk assessment has not been added yet.