Perodipus richardsoni, Allen, Bull. Amer. Mus. Nat. Hist., 7:260, August 21, 1895 (part—the part from Pendennis, Kansas).
Cricetodipus richardsoni, Trouessart, Catalogus Mammalium, 1:581, 1897.
Perodipus montanus richardsoni, ([Bailey], N. Amer. Fauna, 25:144, October 1905 (part—the part from Canadian, Texas).
Perodipus ordii richardsoni, [Goldman], Proc. Biol. Soc. Washington, 30:113, May 23, 1917.
Dipodomys ordii richardsoni, [Grinnell], Journ. Mamm., 2:96, May 2, 1921.
Type.—Male, no. 3025/2345, Amer. Mus. Nat. Hist.; on one of the sources of the Beaver River, Beaver County, Oklahoma; obtained on October 26, 1887, by Jenness Richardson and John Rowley, Jr. (After Allen, original description, type not seen.)
Range.—Southwestern Nebraska, eastern Colorado, northeastern New Mexico, Panhandle of Texas, and western parts of Oklahoma and Kansas; marginal localities are: in Nebraska: Bladen, Haigler; in Colorado: Olney; in New Mexico: Clayton; in Texas: 6 mi. S and 1 mi. W Quitaque, Vernon; in Oklahoma: 3 mi. S Cleo Springs; in Kansas: Medora.
Diagnosis.—Size large (see measurements). Color dark; entire dorsal surface Cinnamon-Buff, purest on sides and flanks, upper parts suffused with black; arietiform markings, pinnae of ears, plantar surfaces of hind feet, dorsal and ventral stripes of tail, blackish; in some specimens the ventral stripe of tail does not extend to tip of pencil. Skull large; rostrum short and wide; nasals long; zygomata relatively heavy; auditory bullae well inflated and wide; thus with short rostrum giving appearance of nearly equilateral triangle; upper incisors long and robust.
Comparisons.—From Dipodomys ordii luteolus, D. o. richardsoni differs as follows: Size smaller in external measurements except length of body which is longer; color darker, except on plantar surfaces of hind feet and dorsal and ventral stripes of the tail which are lighter; ventral stripe of tail, in most specimens, continuous to end of pencil, whereas in D. o. luteolus ventral stripe is present on only proximal two-thirds; skull larger in all measurements taken; zygomatic arch heavier; auditory bullae relatively as well as actually more inflated; external auditory meatus egg-shaped as contrasted to nearly round in D. o. luteolus; pterygoid fossae rounded as compared to ovate in D. o. luteolus.