Specimens examined.—Total number, 5, all in the Field Museum of Natural History.
Perú: 3500 ft., Hacienda Buena Vista, Río Chinchao, 1; 3000 ft., Hacienda San Antonio, Río Chinchao, 1; Huanuco, 1; Ambo, 2.
Mustela frenata agilis Tschudi
Long-tailed Weasel
Plates [27], [28], [29], [39] and [40]
Mustela agilis Tschudi, Fauna Peruana, p. 110, 1844; Gray, Proc. Zoöl. Soc. London, 1865:113, 1865; Taczanowski, Proc. Zoöl. Soc. London, 1874:311, 1874; Taczanowski, Proc. Zoöl. Soc. London, 1881:648, 1881; Allen, Bull. Amer. Mus. Nat. Hist., 35:104; April 28, 1916; Thomas, Proc. U. S. Nat. Mus., 58-224, 1920.
Mustela macrura, Allen, Bull. Amer. Mus. Nat. Hist., 35:103, April 28, 1916.
Mustela frenata agilis, Hall, Carnegie Instit. Washington Publ. 473:110, November 20, 1936; Hall, Physis, 16:176, 1939.
Type.—No type specimen, or type locality more restricted than cold, barren highlands of the Cordillera [referring to Perú] designated.
Range.—High, barren Cordillera of Perú (see Tschudi, orig. descr.); as here restricted, Temperate Life-zone and higher in western Andes and intermountain valleys of Perú. See figure [29] on page [221].
Characters for ready recognition.—Differs from Mustela frenata macrura by lighter color (Chocolate, tone 2 rather than 3, pl. 343, Oberthür and Dauthenay) of upper parts; length of upper tooth-rows, in females, less than 13; inside length of P4 more than 4.6; from M. f. aureoventris by smaller teeth (maximum size just given for agilis); from M. f. boliviensis by lighter color, upper parts being Chocolate, tone 2, pl. 343, rather than tone 4 or darker of Carbon Brown, pl. 342 (Oberthür and Dauthenay).
Description.—Size.—Male: The stuffed skin of an adult, from Lima, measures: Total length, 460; length of tail, 125; length of hind foot, 45.7. A skin alone from Huarochirí has a body, as now stuffed, 277 mm. long. The tail is missing and the bones of the hind feet have been removed.
Female: The mounted specimen, no. 565, Mus. Polonais d'Hist. Nat., yields measurements, taken by me, as follows: Total length, 250; length of tail, 75; length of hind foot, 32.5. The female, no. 21147, from Macate, measures, 300, 102, 34.
Externals.—Longest facial vibrissae, either dark-or light-colored and extending beyond ear; carpal vibrissae either dark-or light-colored and extending to apical pad of fifth digit; hairiness of foot soles as shown in figure [20].
Color.—Tschudi's description of the color is, in substance, as follows: Head, back and tail reddish gray; base of hair gray, followed by broader grayish-yellow ring and then reddish-brown tip; nose simply dark brown or upper lips edged with white; throat, breast, belly and higher parts of inner sides of extremities whitish gray, at times wholly gray, bases of hairs always gray; feet darker than body, almost chestnut brown; tail darker on tip than at base; ears externally dark brown, internally whitish.
No. 565 possibly somewhat faded from exposure to light, has all the upper parts near (14´ j) Ochraceous-Tawny or Cinnamon, and tone 4 of Oberthür and Dauthenay, plate 323; posterior half of each upper lip white; no other white facial markings present; dark spot at each angle of mouth (one spot confluent with color of upper parts); tip of tail probably black (tip missing); underparts white, belly probably originally with slight tinge of yellow or allied color; color of underparts extending distally on forelegs to feet and onto upper sides of toes and on hind legs to just above heels. Least width of color of underparts equal to about one-fourth of greatest width of color of upper parts.
No. 21147, subadult, from Macate, has a white band confluent with the underparts extending anterodorsally anterior to each ear and the posterior third of each upper lip white. Top of head near (n) Mars Brown, and Carbon Brown, tone 3 (pl. 342, Ober. and Dauth.); tip of tail black; remainder of upper parts near (16" j) Tawny-Olive, and Chocolate (tone 2, of pl. 343 of Ober. and Dauth.) or Raw Umber (tone 3 of pl. 301 of Ober. and Dauth.); anterior half of underparts, including posterior sides of forelegs and antipalmar faces of forefeet, white; remainder of underparts tinged with Warm Buff and extended on posterior legs almost to ankles.
No. 8.1.10.1., male adult, from Lima, is also light colored, and as described in no. 21147, except that left side of head has a white spot rather than bar; posterior eighth of each upper lip white; white frontonasal spot present, 11 x 11 mm.; antipalmar faces of forefeet spotted with brown color of upper parts; color of underparts extending distally on hind legs along medial side of foot to point halfway between heel and tip of inner toe.
No. 13257 from Huarochirí in color and color pattern closely resembles no. 21147. It differs from no. 21147 in slightly lighter color of upper parts, entirely white underparts, less extension of color of underparts onto forefeet, few white hairs instead of white band in front of each ear; color of underparts more restricted.
In each of the four specimens, the least width of the underparts, expressed as a percentage of the upper parts, is as follows: no. 13257, 11 per cent; no. 21147, 29 per cent; no. 565, 31 per cent; no. 8.1.10.1., nineteen per cent.
Skull and teeth.—Male (based on no. 8.1.10.1.): See measurements and plates [27]-[29]. As described in Mustela frenata macrura except that: Weight 4.1 grams; basilar length, 42.5; zygomatic breadth more than distance between anterior palatine foramen and anterior margin of tympanic bulla; mastoid breadth less than postpalatal length; tympanic bullae shorter than rostrum.
Female (based on no. 21147): See measurements and plates [39] and [40]. As described in Mustela frenata macrura except that: Weight (no. 21147, subadult), 1.5 grams; basilar length, 35.2; least width of palate less than outside length of P4; tympanic bulla as far posterior to foramen ovale as combined width of five upper incisors; no. 565 answers to the same description but differs from no. 21147 in greater basilar length and larger tympanic bullae which are slightly more projected, at their anterior margins, from the braincase.
To judge from the skull of the female from Macate and the skull of the male from Lima, the skull and teeth of agilis are smaller than in any other South American subspecies of Mustela frenata, except M. f. boliviensis.
Remarks.—Tschudi almost certainly used the name Mustela agilis in a composite sense. His statement (see quoted matter below) about the marked variation in color of this species, as represented by the skins carried by the Indian women as purses, indicates that the forms here designated as Mustela macrura, M. helleri and possibly others additional to the one here called agilis were included by him under the name Mustela agilis. Taczanowski took account of Mustela agilis when he described other species from Perú. Allen (1916:104) and Thomas (1920:224) were not convinced that Mustela agilis and Mustela macrura were distinct species or subspecies.
Search on August 28, 1937, in the Musée d'Histoire Naturelle, at Neuchatel, Switzerland, by Mr. Théodore Delachaux, assistant there, and the writer, revealed no trace of weasels from Tschudi's collection, although some other specimens of mammals that he figured in the "Fauna Peruana" are preserved in that Museum. Not only were the collections of specimens examined but the new catalogue and old catalogue of mammals were vainly searched for mention of weasels deposited by Tschudi. Later, at the British Museum of Natural History, on p, 105 of a personal notebook, of the late Mr. Oldfield Thomas, record was found of his fruitless search for the same specimens of Mustela in May, 1902, at Neuchatel.