Southwest Basins and Ranges | Level 3 (Parent) |
         Northwest Arizona Ranges | Level 4 (Sibling) |
         North Sonoran Desert Ranges | Level 4 |
                 Kofa Area | Level 5 (Child) |
                 Harquahala Area | Level 5 (Child) |
                 Cabeza Prieta Area | Level 5 (Child) |
                 Organ Pipe Area | Level 5 (Child) |
                 Maricopa Area | Level 5 (Child) |
                 South Phoenix Area | Level 5 (Child) |
                 Baboquivari Area | Level 5 (Child) |
                 La Lesna Area | Level 5 (Child) |
                 San Luis Area | Level 5 (Child) |
                 West Tucson-Nogales Area | Level 5 (Child) |
         South Sonoran Desert Ranges | Level 4 (Sibling) |
         Southeast Arizona Ranges | Level 4 (Sibling) |
         Southwest New Mexico Ranges | Level 4 (Sibling) |
         Southeast New Mexico Ranges | Level 4 (Sibling) |
         Trans-Pecos Texas Ranges | Level 4 (Sibling) |