Dipodomys ordii compactus, [Davis], Journ. Mamm., 23:332, August 14, 1942.
Type.—None designated but Poole and Schantz (1942:406) assumed it to be a female, no. 19665/35227, only the skin found, from Padre Island, Cameron County, Texas. April 3, 1888. Purchased from C. K. Worthen.
Range.—Padre and Mustang islands, Cameron County, Texas.
Diagnosis.—Size medium (see measurements); tail short. Color light; entire dorsal surface Light Ochraceous-Buff, purest on sides and flanks, upper parts but lightly suffused with black. A lighter color phase has entire dorsal surface Cartridge Buff, purest on sides and flanks, upper parts but lightly washed with black. In both phases, cheeks white; pinnae of ears, plantar surfaces of hind feet, dorsal stripe of tail, ventral stripe of tail (in most specimens) present on proximal third of tail only, brownish. Skull small; rostrum narrow and long; nasals long; auditory bullae inflated, but greatest breadth across bullae only slightly more than breadth across zygomatic processes of maxillae; interparietal region wide.
Comparisons.—From Dipodomys ordii sennetti, D. o. compactus differs in: Size slightly less; color lighter in all pigmented areas; skull smaller; auditory bullae slightly less inflated; interorbital width less; interparietal region wider; nasals longer.
From Dipodomys ordii attenuatus, D. o. compactus differs in: Body larger; tail shorter; normal color phase darker, and lighter color phase lighter; skull larger; rostrum wider and longer; nasals longer; interorbital region wider; auditory bullae relatively as well as actually less inflated; interparietal region wider; pterygoid fossae large and round as opposed to small and ovoid.
Compared with Dipodomys ordii medius and Dipodomys ordii ordii, D. o. compactus is smaller, lighter in color, and has less inflated auditory bullae and a smaller skull.
Remarks.—This subspecies of Dipodomys ordii was originally described as Dipodomys compactus by True in 1889 and stood as a full species until [Davis] (1942:332) relegated it to subspecific status under Dipodomys ordii. [Davis] (op. cit.) observed close resemblances in external proportions, size of mastoid bullae, width of supraoccipital, and size and shape of the interparietal, between Dipodomys ordii and Dipodomys sennetti and therefore concluded that they were only subspecies of one species. He observed that the difference between Dipodomys compactus and Dipodomys sennetti was of approximately the same degree as that between Dipodomys sennetti and Dipodomys ordii. From this he concluded that all three were subspecies of the one species Dipodomys ordii.
In any sizeable sample of Dipodomys sennetti there are crania closely resembling those of Dipodomys ordii ordii and others closely resembling those of Dipodomys compactus. The external proportions of both D. sennetti and D. compactus are duplicated in D. ordii from El Paso and conversely, specimens with the proportions of typical D. o. ordii occur in populations of D. sennetti and D. compactus. Thus, it appears that [Davis'] usage of the name Dipodomys ordii compactus should stand although there may be a hiatus in geographic occurrence between D. ordii and D. sennetti, as of course there is between D. sennetti and D. compactus.