Peromyscus leucopus texanus (Woodhouse)
White-footed Mouse
Hesperomys texana Woodhouse, Proc. Acad. Nat. Sci. Philadelphia, 6:242, 1853. (Type probably from the vicinity of Mason, Mason County, Texas.)
Peromyscus leucopus texanus Osgood, N. Amer. Fauna, 28:127, April 17, 1909.
Specimens examined, 8 as follows: 7 km. S and 2 km. W San Fernando, 1; 12 km. N and 4 km. W Ciudad Victoria, 2; 70 km. [by highway] S Ciudad Victoria and 2 km. W El Carrizo, 4.
Peromyscus ochraventer new species
Brown-bellied Wood Mouse
Type.—Female, adult, skin and skull; no. 36958, Univ. Kansas Mus. Nat. Hist.; 70 km. [by highway] S Ciudad Victoria and 6 km. W of the [Pan-American] highway [at El Carrizo], Tamaulipas, Mexico; 12 January 1950; obtained by William J. Schaldach, Jr., original no. 566.
Range.—Known only from the type locality; probably found in other localities along the humid, east face of the Sierra Madre Oriental in Tamaulipas.
Diagnosis.—Size medium (see measurements); upper parts near Ochraceous Tawny (capitalized color terms after Ridgway, Color Standards and Color Nomenclature, Washington, D. C., 1912), brighter on sides and duller on back; cheeks, sides of neck, shoulders and upper forelegs lighter, between Ochraceous Buff and Ochraceous Orange; eye ring dark; underparts light Cinnamon Buff, breast patch brighter; ears dusky, sparsely covered with hairs colored like back; feet white; tail scaly in appearance, indistinctly bicolored with short dark hairs above and short pale hairs below; skull without beaded or ridged supraorbital border; rostrum expanded anteriorly with sides almost parallel; teeth with strongly developed outer accessory cusps on the first and second upper molar teeth; anteriormost loph (parastyle-protoconule of Goldman, N. Amer. Fauna, 43:11, September 23, 1918) of the first upper molar large, almost as broad as greatest breadth of tooth.
Comparisons.—Peromyscus ochraventer has been compared with P. difficilis (specimens from Veracruz), P. boylei (Veracruz), P. banderanus (Guerrero), P. mexicanus (Veracruz), P. furvus (Veracruz), and P. latirostris (San Luis Potosí). From P. difficilis, P. ochraventer differs in having underparts distinctively brownish, rostrum expanded anteriorly with sides almost parallel, anteriormost loph of the first upper molar larger, and auditory bulla smaller. From P. boylei, P. ochraventer differs in having underparts distinctively brownish, tail less distinctly bicolored, rostrum expanded anteriorly with sides almost parallel, and anteriormost loph of the first upper molar larger. From P. banderanus, P. ochraventer differs in having underparts distinctively brownish, tail less distinctly bicolored, rostrum expanded anteriorly with sides almost parallel, anteriormost loph of the first upper molar larger, auditory bulla smaller, and in lacking a beaded or ridged supraorbital border. From P. mexicanus, P. ochraventer differs in having underparts distinctively brownish, tail not irregularly blotched with dusky, rostrum expanded anteriorly with sides almost parallel, anteriormost loph of the first upper molar larger, and in lacking a beaded or ridged supraorbital border. From P. furvus and P. latirostris, P. ochraventer differs in being smaller, having underparts distinctively brownish, tail not irregularly blotched with dusky, rostrum proportionately shorter, and interpterygoid space relatively narrower.
Remarks.—Peromyscus ochraventer is considered to be a distinct species showing little evident relationship with other Mexican Peromyscus. In the shape of the skull, especially the anterior expansion of the rostrum, P. ochraventer seems to be related to P. furvus and P. latirostris, a series of the latter being made available for examination by Dr. George G. Lowery, Jr., of the Museum of Zoology at Louisiana State University. However, the rostrum of these two larger species is proportionately longer than the rostrum of P. ochraventer. In size, coloration and most cranial features, P. ochraventer resembles P. mexicanus, although the absence, instead of presence, of a supraorbital bead or ridge, the almost parallel-sided, instead of more pointed, rostrum and the larger, instead of smaller, interiormost loph of the first upper molar in P. ochraventer are well-marked differences. The baculum of P. ochraventer is much shorter with a proportionately heavier base and shaft than the baculum of P. mexicanus mexicanus (from Veracruz) and P. m. saxatilis (from Costa Rica). The geographic range of Peromyscus ochraventer is not known to meet that of P. mexicanus; the nearest place to the type locality of P. ochraventer from which P. mexicanus has been taken is at Xilitla approximately 225 kilometers to the southward in San Luis Potosí (Dalquest, Occ. Papers Mus. Zool., Louisiana State Univ., No. 28:8, July 10, 1950).