1877. Putorius mexicanus Coues, Fur-bearing animals, U. S. Geol. Surv. Territories, Misc. Publ., 8:42, a nomen nudum [cited by Coues in synonymy as "Putorius mexicanus, Berlandier, MMS. ic. ined. 4 (Tamaulipas and Matamoras)">[.
Distribution in Tamaulipas.—Central and northern parts of state.
The specimen from Jaumave is clearly M. f. frenata, but the other from northwest of Altamira has many characters of the subspecies M. f. tropicalis and is an intergrade between the two subspecies. In cranial features and in measurements the animal is like frenata. For example: least width of palate more than length of P4; distance between anterior border of auditory bulla and foramen ovale equal to the width of four (including I3) upper incisors; depth of tympanic bulla less than distance between it and foramen ovale; length of tail amounting to 82 per cent of length of head and body. The coloration is more nearly like that of tropicalis. For example, the region between the ears and the region behind the ears as far as the shoulders is almost black; hairs of the soles of the forefeet are of the same color as in tropicalis. But, width of the whitish underparts amounts to 53 per cent of the circumference of the body; in this respect the specimen is like frenata. I refer the specimen to frenata because, to me, it is slightly more nearly like it.
Measurements.—The male from 6 mi. N, 6 mi. W Altamira affords measurements as follows: 500; 226; 53; 23; basilar length (Hensel), 49.5; breadth of rostrum, 14.3; interorbital constriction, 11.9; orbitonasal length, 15.2; mastoid breadth, 27.2; zygomatic breadth, 32.4; tympanic bullae, length, 16.8; breadth, 7.5; length of m1, 5.7; P4, lateral length, 5.4, medial, 5.8; M1, breadth, 4.6, length, 2.4; depth of skull at anterior edge of basioccipital, 14.7.
Records of occurrence.—Specimens examined, 2: Jaumave, 2400 ft., 1; 6 mi. N, 6 mi. W Altamira, 1.
Additional records (Hall, 1951:347): Matamoros; Miquihuana.
Mustela frenata tropicalis (Merriam)
1896. Putorius tropicalis Merriam, N. Amer. Fauna, 11:30, June 30, type from Jico, Veracruz.
Distribution in Tamaulipas.—Tropical area in south part of state; reported only from 50 mi. south of Ciudad Victoria (Hall, 1951:366).