Fresno kangaroo rats are a subspecies. You can actually tell this from their scientific name. A species is designated by two words in its scientific name, the genus is the first word, and the species is the second word. In Fresno Kangaroo Rats, Dipodomys is the genus, and nitratoides is the species name. The genus represents a larger group, similar to a last name, while the species name is specific to the species. In subspecies, the animals are members of the same species and so have the same genus and species name (Dipodomys nitratoides).

However, they are different enough to be considered subspecies, and so a third name is tacked onto the genus and species, exilis in this case. There are two other subspecies of Dipodomys nitratoides, the Tipton kangaroo rat, Dipodomys nitratoides nitratoides, and the short-nosed kangaroo rat, Dipodomys nitratoides brevinasus. All the subspecies are very similar to each other, but have differences in size.