The desert tortoises (Gopherus agassizii and Gopherus morafkai) are species of tortoise native to the Mojave desert and Sonoran desert of the southwestern United States and northwestern Mexico and the Sinaloan thornscrub of northwestern Mexico. Gopherus agassizii is distributed in western Arizona, southeastern California, southern Nevada, and southwestern Utah. The species name agassizii is in honor of Swiss-American zoologist Jean Louis Rodolphe Agassiz.