Comparisons.—From Dipodomys ordii chapmani, D. o. longipes differs as follows: Size larger; color lighter; skull larger in all measurements taken; auditory bullae much more inflated.
From Dipodomys ordii cupidineus, D. o. longipes differs in: Size larger; color lighter; rostrum longer and narrower; nasals longer; interorbital width greater; breadth across zygomatic processes of maxillae greater; auditory bullae more inflated; zygomatic arches heavier and more bowed laterally.
For comparisons with Dipodomys ordii medius and Dipodomys ordii nexilis see accounts of those subspecies.
Remarks.—The large reddish Dipodomys ordii longipes is notably distinct from those subspecies which have adjoining ranges. The subspecies closest, geographically and morphologically, is Dipodomys ordii nexilis with which D. o. longipes intergrades, in size of body and color of pelage, north of the San Juan River, Utah. This intergradation is probably the result of a migration of D. o. longipes around the head waters of, or above the place in, the river where there is constantly flowing water. It is probably impossible for these animals to cross a constantly flowing stream as wide as the San Juan is in its lower reaches. The San Juan River, however, in 1896, and again in 1934, was so low that it ceased to flow below Aneth ([Gregory], 1938:6, 19). Consequently, at these times, Dipodomys could have crossed the river from one side to the other, at least above the Goosenecks. Intergradation is noted also with Dipodomys ordii medius at Chama Canyon, New Mexico, where the color is like that of D. o. medius, although the cranial characters are as in D. o. longipes; specimens from Chama Canyon are referred to the latter. Ten miles southwest of Quemado and at Riley, New Mexico, intergradation with Dipodomys ordii ordii occurs in the shape of the nasals and the intermediate size of the skull. In color and external measurements these animals more closely resemble D. o. longipes.
[Goldman] (1933:469) described Dipodomys ordii cleomophila from 5 miles northeast of Winona, Coconino County, Arizona, and gave as distinctive characters "upper parts distinctly darker, ... black facial markings more distinct; skull slightly different." These comparative statements were made in reference to Dipodomys ordii longipes. While it is true that the animals which [Goldman] examined are darker and show some slight cranial differences, these animals, in my opinion, are not sufficiently distinct to warrant their separation from D. o. longipes. In the degree of expansion of the auditory bullae, the width of the rostrum, the length of the nasals and interorbital width, animals from 5 miles northeast of Winona (2 specimens) are within the range of individual variation shown by D. o. longipes. The color is darker, being more as in Dipodomys ordii chapmani. Specimens examined from 10 miles north of Angell, Springerville, Tanner Tank and Cedar Ranch Wash, Arizona (listed by [Goldman] as referable to D. o. cleomophila), and those from Wupatki Ruins, Arizona, agree with D. o. longipes except that the width across the maxillary arches is greater. This greater width across the maxillary arches and the darker color of animals from Winona and Wupatki Ruins, in my opinion, afford insufficient basis for the recognition of the subspecies Dipodomys ordii cleomophila [Goldman] which, therefore, is placed as a synonym of Dipodomys ordii longipes (Merriam).
Specimens examined.—Total, 244, distributed as follows:
Utah: San Juan County: 1 mi. N Bluff, 3500 ft., 1 (UU); 1/2 mi. N Bluff, 3300 ft., 7 (UU); Bluff, 2 (UU); Johns Canyon, San Juan River, 5150 ft., 2 (UU).
Arizona: Coconino County: 20 mi. NE Lees Ferry, 1 (USNM); 2 mi. S Endische, 2 (MVZ); 2 mi. SE Endische Spring, Navajo Mountain, 1 (MVZ); 1/2 mi. W Navajo Spring, Echo Cliffs, 4 (MVZ); 5 mi. S Navajo Mountain, 2 (MVZ); 7 mi. SE Navajo Mountain, 1 (MVZ); Moa Vae, 10 (MVZ); 2 mi. S Grand Canyon Bridge, 1 (USBS); Tuba, 4 (1 USBS; 3 AMNH); 12 mi. above mouth of Moencopi Wash, 2 (USBS); 14 mi. NW Cedar Ridge, 1 (USBS); 5 mi. N Cameron, 1 (MVZ); Painted Desert, 6 mi. NE Cameron, 1 (MVZ); 5 mi. E Little Colorado River on Tuba road, 2 (MVZ); Cameron, 4200 ft., 17 (8 LACM; 9 MVZ); Wupatki Ruins, 4 (MVZ); Deadmans Flat, 6400 ft., NE San Francisco Mt., 3 (MVZ); 3 mi. NW Winona, 4 (USBS); 5 mi. NE Winona, 2 (USBS); 10 mi. N Angell, Walnut Tank, 8 (USBS); Cedar Ranch Wash, 3 mi. above mouth, 5 (USBS); Tanner Tank, 2 (USBS); Tanners Crossing, Painted Desert, 1 (USBS). Navajo County: Right fork, Segi-ot-Sosie Canyon, 11 mi. NW Kayenta, 2 (MVZ); Bat Woman Canyon, 13 mi. W Kayenta, 1 (MVZ); Kayenta, 4 (USBS); Segi Canyon, 12 mi. WSW Kayenta, 1 (MVZ); Segi Canyon, 13 mi. WSW Kayenta, 1 (MVZ); Oraibi, 6000 ft., 9 (4 USBS; 5 MVZ); Walpi, 2 (USBS); Keam Canyon, 12 (6 USBS; 3 USNM; 3 MVZ); Winslow, 6 (USBS); Zuni Well, 7-1/2 mi. N Adamana, 9 (MVZ); Holbrook, 10 (USBS); Long Canyon, 3 (AMNH); Bubbling Springs, 2 (AMNH). Apache County: Dinnehotso, 5000 ft., 3 (MVZ); Lukachukai, 1 (USBS); Chin Lee, 6 (USBS); 9 mi. SW Chin Lee, 1 (USBS); 7 mi. from mouth, Canyon de Chelly, 1 (USBS); Fort Defiance, 2 (USNM); Ganado, 1 (USBS); Springerville, 2 (USBS); 3 mi. SE Springerville, 5 (USBS); unspecified, 4 (2 USBS; 2 USNM); Trash Tank, Grand Canyon, 2 (USBS).
New Mexico: San Juan County: Ship Rock, 4 (USBS); Fruitland, 9 (USBS); Blanco, 1 (USBS); Chaco Canyon National Monument, 4 (MVZ). Rio Arriba County: Chama Canyon, 1 (USBS). McKinley County: 2 mi. W Mariano Lake, 3 (MVZ); Gallup, 6 (USBS); Wingate, 6 (USBS); Thoreau, 2 (USBS); Zuni River, 1 (USBS). Sandoval County: Juan Tafoya, 1 (USBS). Valencia County: 8 mi. SE Grants, 7 (UM); 9 mi. SSE Grants, 5 (UM); 2-1/2 mi. E El Morro P. O., Zuni Mts., 1 (LACM); Laguna, 1 (USBS); Laguna Indian Reservation, 7 (LACM). Catron County: Cougar Ranch, NE Adams Diggings, 1 (CAS); 10 mi. SW Quemado, 1 (USBS). Socorro County: 1 mi. S Bernardo, 1 (MVZ); Riley, 1 (USBS).