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 large (see measurements); upper parts dusky brown, paler on sides, individual hairs on middle of back tipped with black or with Light Pinkish Cinnamon (capitalized color term after Ridgway, Color Standards and Color Nomenclature, Washington, D. C., 1912); head grayer especially on cheeks; underparts dusky (dark bases of white-tipped hairs exposed), hairs on throat and inguinal region of adult specimen white to base; outside of legs dusky gray; tail scaly in appearance and sparsely covered with short, blackish hairs above and short, whitish hairs below; skull with auditory bulla large; external auditory meatus large; palatine region narrow; sides of interpterygoid fossa concave and broadly excavated near posterior end of molariform tooth-rows.
Comparison.—Neotoma angustapalata has been compared with N. torquata (specimens from Veracruz and Puebla), N. navus (Coahuila), N. mexicana (New Mexico), N. micropus (Tamaulipas), N. albigula (Coahuila), N. ferruginea (Jalisco), and N. distincta (from published description in Goldman, N. Amer. Fauna, 31:64, October 19, 1910). Neotoma angustapalata differs from N. micropus and N. albigula in having a deep, instead of a shallow, anterointernal reentrant angle on the first upper molar and seems to belong to the N. mexicana group of wood rats. Neotoma angustapalata differs from N. navus, N. mexicana, N. torquata, and N. ferruginea in larger size, darker underparts, tail with sparse, short hairs and scaly appearance, more broadly concave sides of interpterygoid fossa at posterior end of molariform tooth-rows, larger external auditory meatus, and narrower palatine breadth. Neotoma angustapalata differs from the description of N. distincta in having a faintly bicolored tail, no ochraceous pectoral band, broadly concave sides to interpterygoid fossa, and narrower palatine breadth.
Remarks.—Neotoma angustapalata is represented by two specimens; the type and another specimen, an adult male, no. 37062, with skin and broken skull. The description takes into account both of these specimens. The most significant characteristics of N. angustapalata are its scaly-appearing tail with short, sparse hairs, dusky underparts, broadly concave sides of the interpterygoid fossa at the posterior end of molariform tooth-rows, and the narrow palatine breadth. Among named kinds of Neotoma, the newly named species most closely resembles N. torquata and N. distincta; however, it is geographically widely separated from these two species. Neotoma navus of southeastern Coahuila is the only other member of the N. mexicana group in northeastern Mexico.
These wood rats were taken in rocks and crevices at the base of a small hill in thick vegetation growing in deep humus. Schaldach termed the trapping site as "arid tropical tending toward humid tropical".
Measurements.—The subadult, male holotype measures as follows: Total length, 325; length of tail, 154; length of hind foot, 36; length of ear from notch, 29; basilar length (of skull), 33.9; zygomatic breadth, 22.1; interorbital breadth, 5.7; length of nasals, 15.2; length of incisive foramina, 8.7; length of palatal bridge, 8.5; least breadth of palate between first upper molars, 2.7; greatest breadth of interpterygoid space, 4.1; alveolar length of upper molariform tooth-row, 9.6. The adult, male, no. 37062, measures as follows: Total length, 380; tail vertebrae, 195; hind foot, 42; ear from notch, 31; interorbital breadth (of skull), 6.4.
Specimens examined, 2, from the type locality.
Rattus rattus subsp.
Black Rat
Specimens taken, 2 from 70 km. [by highway] S Ciudad Victoria and 6 km. W of the [Pan-American] highway [at El Carrizo].