Long-tailed Weasel
Plates [1], [27], [28], [29], [30], [37], [38], [39] and [40]
Mustela macrura Taczanowski, Proc. Zoöl. Soc. London, 1874:311, pl. 48, May 19, 1874; ibid., 1881:647, May 17, 1881; ibid., 835, November 15, 1881; Lönnberg, Arkiv för Zool., 8 (no. 1):21, 1913 (?); Hollister, Proc. Biol. Soc. Washington, 28:143, July 10, 1914; Allen, Bull. Amer. Mus. Nat. Hist., 35:101, April 28, 1916; Lönnberg, Arkiv för Zool., 14 (no. 4):11, 1921.
Putorius (Gale) braziliensis frenatus, Coues, Fur-bearing animals, p. 142, 1877.
Mustela jelskii Taczanowski, Proc. Zoöl. Soc. London, 1881:647, May 17, 1881.
Mustela affinis, Lönnberg, Arkiv för Zool., 8 (no. 1):21, July 12, 1913.
Mustela aureoventris, Thomas, Proc. U. S. Nat. Mus., 58:224, 1920.
Mustela frenata macrura, Hall, Carnegie Instit. Washington Publ. 473:110, November 20, 1936; Hall, Physis, 16:176, 1939.
Type.—Male, adult, mounted skin, with skull separate; no. 561, Mus. Polonais d'Hist. Nat. (Warsaw, Poland); Lake Junín, central Perú; 1873; obtained by M. Jelski.
The skull (plates [27]-[29], [30]), mounted with the skin but removed by me for study, lacks the right jugal, the basisphenoid, the basioccipital and parts of each exoccipital bearing the exoccipital condyles. The right tympanic bulla, although detached from the skull, is preserved separately. The teeth all are present and entire. The skin is fairly-well mounted, in a good state of preservation, and shows no fading due to exposure to light.
Range.—Altitudinally, 3200 (Guainche) to at least 12000 feet (Pichincha); Upper Subtropical and Temperate life-zones of central Perú and Ecuador north from the states of Apurimac and Cuzco, Perú, to San Antonio, northern Ecuador. See figure [29] on page [221].
Characters for ready recognition.—Differs from Mustela africana stolzmanni by absence of median, longitudinal, abdominal stripe of same color as upper parts; presence of p2 and two roots rather than one root on P2; from Mustela frenata helleri, M. f. affinis and M. f. aureoventris by lighter color of upper parts which are Chocolate tone 3, pl. 343, Oberthür and Dauthenay, whereas, with reference to the same color standard, the colors are: in helleri, Carbon Brown, tone 3, pl. 342; in affinis, Reddish Black, tone 2, pl. 344; in aureoventris, Reddish Black, tone 4, pl. 344; from M. f. agilis by darker color (Chocolate, tone 3 rather than 2, pl. 343, Oberthür and Dauthenay) of upper parts, length of upper tooth-rows, in females, more than 13, inside length of P4 more than 4.6; from M. f. boliviensis by lighter color of upper parts which are as above rather than tone 4 of Carbon Brown, pl. 342 of Oberthür and Dauthenay, and larger size (in males, hind foot more than 45 and m1 more than 5.6).
Description.—Size.—Male (measurements as recorded by Taczanowski in the original description, for two specimens, type and topotype, with correction of the length of tail of his "female" [= male]): Total length, 420, 415; length of tail, 150, 145; length of hind foot, 51, 51. An adult from Yana Mayo, Río Tarma, was measured by Hendee as 394, 134. Hind foot relaxed measures, 47. Tail 55 per cent as long as head and body. Length of hind foot more than basal length.
Female (based on measurements given by Taczanowski (1881:647) of no. 564): Total length, 323; length of tail, 120; length of hind foot, 37. Tail 59 per cent as long as head and body. Length of hind foot approximately equal to basal length.
Differences in external measurements of the two sexes are: Total length, 87; length of tail, 23; length of hind foot, 13.
Externals.—Longest facial vibrissae extending beyond ear; carpal vibrissae color of either upper parts or underparts; hairiness of foot-soles as shown in figure [20].
Color.—(Based on specimens from Cutervo and south thereof). Rarely few white hairs between eyes and in front of ears; top of head posteriorly to slightly behind eyes, near (n) Chestnut-Brown (Ridgway) and Carbon Brown, tone 2 or darker (pl. 342, Oberthür and Dauthenay); posterior half of upper lip rarely white; dark spots at angles of mouth absent; tip of tail black; remainder of upper parts near (l) Russet (Ridgway) and Chocolate, tone 3 (pl. 343, Ober. and Dauth.); underparts white or whitish on medial sides of forelegs, otherwise cream color with tinge of Ochraceous-Buff; color of underparts extended distally on posterior sides of forelegs to just below elbow (in type specimen) or onto forefeet (in specimen from Yana Mayo) and on medial sides of hind legs to points between knees and ankles. Least width of color of underparts averages (in six skins) 17 (14-21) per cent of greatest width of color of upper parts. Black tip of tail longer than hind foot and averaging 36 (32-49) per cent of length of tail-vertebrae.
Skull and teeth.—Male (based on type specimen and no. 562): See measurements and plates [27]-[30]; weight, not known; basilar length, 43.2 (40.8 and 45.5); zygomatic breadth more or less than distance between condylar foramen and M1 and more than that between anterior palatine foramen and anterior margin of tympanic bulla; mastoid breadth more or less than postpalatal length; postorbital breadth more than length of upper premolars and greater than width of basioccipital, measured from medial margin of one foramen lacerum posterior to its opposite; interorbital breadth more than distance between foramen opticum and anterior margin of tympanic bulla; breadth of rostrum less than length of tympanic bulla; least width of palate more than inside length of P4; anterior margin of tympanic bulla as far posterior to foramen ovale as width of 4 (including I3) upper incisors; height of tympanic bulla not more than distance from its anterior margin to foramen ovale; length of tympanic bulla more than length of lower molar and premolar tooth-row and longer or shorter than rostrum; anterior margin of masseteric fossa below or behind m2.
Female (based on no. 564, from Cutervo, Perú, type specimen of Mustela jelskii Taczanowski): See measurements and plates [37]-[40]; weight, not known; basilar length, 38±; zygomatic breadth less than distance between condylar foramen and M1 and not greater than that between anterior palatine foramen and anterior margin of tympanic bulla; postorbital breadth more than alveolar length of upper premolars and (probably) more than width of basioccipital measured from medial margin of one foramen lacerum posterior to its opposite; least width of palate more than inside length of P4; tympanic bulla as far posterior to foramen ovale as width of at least 5-1/2 upper incisors; height of tympanic bulla less than distance from its anterior margin to foramen ovale; length of tympanic bulla more than length of lower molar and premolar tooth-row and longer or shorter than rostrum.
As compared with that of helleri, the skull of the male of macrura from Junín southward has a lesser mastoid breadth, notably smaller teeth, and a flatter skull which averages lighter throughout. The skulls of females available indicate that the skull and teeth are larger than in agilis.
Remarks.—Seven years after Taczanowski named this subspecies, he applied the name jelskii to a female taken farther north than the original examples of macrura. As indicated in synonymy, various other names have been applied to animals included by the present author in this subspecies.
Mustela frenata macrura intergrades with M. f. affinis as shown by practically all the referred specimens from north of Junín. As one proceeds northward the color of the weasels becomes progressively darker and the teeth become larger until the conditions found in affinis are met with near the northern border of Ecuador. From the material available it appears that the light-colored upper parts found in macrura characterize weasels of, at least, the Temperate Zone, from Marcapata, Perú, to near Quito, Ecuador. West of the range of macrura there exists the still lighter-colored subspecies, M. f. agilis. Immediately adjacent on the north, east, and south, darker-colored weasels occur. So far as color is concerned, the geographic range of the subspecies M. f. macrura is not difficult to define. However, the small size of the teeth characterizes only that part of this light-colored subspecies from Junín southward including the subspecies boliviensis at the southern extremity of the range of the species. From Cutervo northward the light-colored weasels of the Temperate Zone have teeth similar in size to those of the darker, more northern affinis. To designate the slightly larger-toothed, light-colored animals from Ecuador as a subspecies distinct from affinis and macrura is one solution but at present it seems best to refer all of these light-colored animals to macrura.
The type specimen and topotype no. 562 differ more in the amount of inflation of the tympanic bullae than adult males of comparable ages from a given locality usually do. In other respects, the differences between the two skulls are not greater than those ordinarily found in specimens from the same locality. No. 562 has the tympanic bullae greatly, relative to the other South American weasels, inflated posteriorly. Otherwise, the bullae agree with those of the type specimen.
Specimens from southwestern Ecuador, average large, and include the largest specimens of the species Mustela frenata seen from South America. A subadult male, no. 61406, in the American Museum of Natural History, is the largest. Its external measurements are 482, 191, 56. The basilar length of the skull is 48.2 and the zygomatic breadth is 30.3. Although not so large as this specimen, the corresponding measurements of specimens from Alamor, El Chiral, and even from as far away as Sigsig also are distinctly large.