Oxymycterus quaestor occurs in southeastern Brazil, eastern Paraguay, and northeastern Argentina. Its back is dark orange-brown with black streaks, and it has been recorded on the ground in humid and disturbed vegetation.
Adults have a head-and-body length of 135–180 mm and a tail length of 97–143 mm. The back is dark orange-brown with black streaks; the underside is described as dark yellowish gray to dark orange.
It has been recorded on the ground in humid and disturbed vegetation.
An extinction-risk assessment has not been added yet.