On the basis of skulls alone, specimens of frenata from Tlalpam and those of leucoparia from Los Reyes can hardly be distinguished. This fact, and the circumstance that the specimens from the northern part of the range of leucoparia closely resemble frenata in color, constitute sufficient evidence for regarding the two as only subspecifically distinct. The female, no. 26153 from Artenkiki, as mentioned above, approaches true frenata in coloration. On this account it is not to be regarded as typical and it was because no other skulls of adult females were available that this one was used for comparison with females of allied races.
M. f. leucoparia is, then, a subspecies of the large, temperate-zone group and is unique in possessing the maximum extent of white facial markings.
None of the seven skulls shows signs of having had the frontal sinuses infested with parasites.
Specimens examined.—Total number, 8, all from México. Localities are listed by states from north to south. Specimens from Michoacán are in the United States National Museum; one from Río Santiago is in the British Museum of Natural History; all others are in the American Museum of Natural History.
Nayarit. Tepic, 1.
Jalisco. Río Santiago, 1; Los Masos, 1; "Artenkiki" (J. A. Allen, 1906, p. 238, writes "Artenkikil" and, on p. 259, "Artenkiki."), 1.
Michoacán. Zamora, 1; Los Reyes, 1; Pátzcuaro, 3.
Mustela frenata perotae Hall
Long-tailed Weasel
Mustela frenata perotae Hall, Carnegie Instit. Washington Publ. 473:100, November 20, 1936.
Putorius frenatus, Merriam, N. Amer. Fauna, 11: pl. 3, fig. 2, June 30, 1896.
Type.—Female, adult, skull and skin; no. 54278, U. S. Nat. Mus., Biol. Surv. Coll.; 12,500 feet, Cofre de Perote, Veracruz, México; May 26, 1893; obtained by E. W. Nelson; original no. 4864.
The skull (plates, 37-39) lacks the right zygomatic arch. Left p2 is missing. The skin is fairly well made and in good condition except that the extreme tip of the tail has been broken off and there are two holes in the right hind leg. The underparts show the beginning of a spring molt.
Range.—From 7500 (?) feet (Perote) to 13,500 feet (Popocatépetl), Upper Sonoran, Transition and Boreal life-zones of mountains along Puebla-México boundary, eastward to western central Veracruz and south into Oaxaca. See figure [29] on page [221].
Characters for ready recognition.—Differs from M. f. frenata, its nearest relative, in extension from head of blackish onto anterior fourth of neck; restriction of color of underparts (least width of same less than 37 per cent of greatest width of color of upper parts), height of tympanic bulla less than distance from its anterior margin to foramen ovale; from M. f. macrophonius and M. f. goldmani in presence of, rather than absence of, color of underparts on hind feet; upper parts (black) Brussels Brown rather than Argus Brown or darker; from M. f. tropicalis in larger size (adult female with total length more than 400, basilar length more than 40, weight of skull more than 3 grams); postorbital breadth less than combined length of upper premolars; m1 more than 5.4 long; from M. f. leucoparia in white facial markings so restricted that spot between eyes is not confluent with white stripe in front of ear, or, if so, narrowly (less than 4 wide) confluent; color of upper parts extending onto antipalmar face of forefoot, least width of color of underparts not more than 40 per cent of greatest width of color of upper parts; height of tympanic bulla not more than three-fifths distance from its anterior margin to foramen ovale.
Description.—Size.—Male: A nontypical specimen from Cerro San Felipe, Oaxaca, measures: Total length, 500; length of tail, 205; length of hind foot, 52.
Female: The type specimen, measures: Total length, 418; length of tail, 160; length of hind foot, 45.
In this male the tail is 70, and in the female, 62 per cent as long as the head and body. In each the hind foot is longer than the basal length.
The differences in external measurements between these two specimens, representing the two sexes, are: Total length, 82; length of tail, 45; length of hind foot, 7.
Externals.—As described in Mustela frenata frenata.
Color (based on type specimen).—Color and color pattern as described in Mustela frenata frenata except that: blackish of sides and top of head extends one-fourth of way back to shoulders from ears; throat and breast as well as chin white; remainder of underparts near (16´ c) Ochraceous-Buff; least width of color of underparts equals 36 per cent of greatest width of color of upper parts; black tip of tail equal to 28 per cent of length of tail-vertebrae.
Skull and teeth.—Male (based on a referred specimen from Cerro San Felipe which certainly is nontypical): See measurements. As described in Mustela frenata frenata except that: Weight, 4.9 grams; basilar length, 49.2; postorbital breadth more than distance between posterior borders of P4 and P2; tympanic bulla as far posterior to foramen ovale as width of 5 upper incisors; height of tympanic bulla less than distance from its anterior margin to foramen ovale; zygomatic breadth less than distance between condylar foramen and M1 or than between anterior palatine foramen and anterior margin of tympanic bulla.
Female (based on type specimen, an adult): See measurements and plates [37]-[39]. As described in Mustela frenata frenata except that: Weight 3.4 grams; basilar length, 43.5; zygomatic breadth less than distance between condylar foramen and M1 or than between anterior palatine foramen and anterior margin of tympanic bulla; postorbital breadth less than width of basioccipital measured from medial margin of one foramen lacerum posterior to its opposite; tympanic bulla as far posterior to foramen ovale as width of 5 or 6 upper incisors; height of tympanic bulla one-half to three-fifths distance from its anterior margin to foramen ovale; length of tympanic bulla more than length of lower molar and premolar tooth-row and longer than rostrum.
The skull of the female is 33 per cent lighter than that of the nontypical (and smaller than average) male from Cerro San Felipe.