Compared with Dipodomys ordii longipes, D. o. medius is darker and smaller.
Remarks.—This hitherto undescribed race of Dipodomys ordii can readily be distinguished from any of its near neighbors by the characters set forth under diagnosis and comparisons.
Intergradation is noted with D. o. ordii, D. o. longipes, D. o. montanus and D. o. richardsoni. Among named races D. o. medius shows closest affinities with D. o. richardsoni but the two are easily separable. The northwestern extremity of the range of D. o. medius is an area of intergradation in which no specimens are clearly of one subspecies or the other. In specimens from 5 miles east of Abiquiu, New Mexico, three-way intergradation occurs. These animals are like D. o. medius in size, D. o. longipes in color and their cranial proportions are as in D. o. montanus. At Deer Creek, New Mexico, and at Monahans, Texas, the animals show intergradation in size of body and agree with D. o. ordii in cranial proportions. In specimens from 6 miles southwest of Muleshoe, Texas, intergradation with D. o. richardsoni in the shape of the skull and width of the rostrum is noted. In the sum total of characters studied, however, these specimens are referable to D. o. medius.
Specimens examined.—Total, 129, distributed as follows:
New Mexico: Rio Arriba County: 2 mi. SE El Rito, 2 (KU); Rio Alamosa, 15 mi. N Ojo Caliente, 1 (USBS); 6 mi. E Abiquiu, 4 (USBS); Rinconada, 5 (USBS); Espanola, 6 (USBS). Sandoval County: 12 mi. NW Alameda, 5500 ft., 3 (MVZ). Santa Fe County: Seton's Ranch, near Santa Fe, 1 (USBS); 8 mi. SW Santa Fe, 8 (KU); San Pedro, 3 (USBS). San Miguel County: Pecos, 2 (USBS); 3 mi. S Pecos, 2 (USBS); Rowe, 6 (LACM). Bernallilo County: Bear Canyon, Sandia Mountains, 7 (USBS); Pajarito, 3 (MVZ). Guadalupe County: Santa Rosa, 10 (USBS). Lincoln County: 44 mi. NW Roswell, 5 (MVZ). De Baca County: 8 mi. N Fort Sumner, 9 (USBS). Roosevelt County: Kenna, 4 (LACM). Curry County: 4 mi. W and 2-3/4 mi. N Clovis, 1 (MVZ). Chaves County: 40 mi. N Roswell, 2 (USBS); 35 mi. N Roswell, 2 (USBS); 15 mi. NE Roswell, 8 (LACM); Stinking Springs Lake, 3 (USBS).
Texas: Bailey County: 6 mi. SW Muleshoe, 5 (UM); 9 mi. SW Muleshoe, 2 (UM). Garza County: 7 mi. E Post, 5 (UM). Martin County: Stanton, 4 (USBS). Howard County: 6 mi. NE Coahoma, 7 (UM); 1 mi. S Coahoma, 1 (UM); 5 mi. W Big Springs, 2400 ft., 1 (MVZ). Mitchell County: Colorado, 5 (USBS). Winkler County: 20 mi. N Monahans, 1 (USBS). Ward County: Monahans, 1 (USBS).
Dipodomys ordii obscurus (Allen)
Perodipus obscurus Allen, Bull. Amer. Mus. Nat. Hist., 19:603, November 12, 1903.
Dipodomys ordii obscurus, [Grinnell], Journ. Mamm., 2:96, May 2, 1921.