None of the ten skulls examined shows malformation of the frontal region due to infestation of the frontal sinuses by parasites. Possibly three of the four adults were infested, although not severely.
Specimens examined.—Total number, 27, arranged by localities from north to south and unless otherwise indicated in the United States National Museum.
Colombia: El Carmen, 1[2]; W. Cundinamarca, 1[7]; Muzzo [= Muzo?], 1[4]; Bogotá, 1; Castillo, near Bogotá, 1[7]; Fambrias, near Bogotá, 1[75]; Bogotá district, 1[2]; Choachí, 9 (1[75], 2[7], 1[84]); Páramo de Choachí, 2 (1[2], 1[84]); Laguna del Verjón (= City of Bogotá), 1[75]; Quetame, 2[2]; Fusagasuga, 1; Caqueta, 2[2]; no locality more definite than Colombia, 3 (1[7]).
Mustela frenata aureoventris Gray
Long-tailed Weasel
Mustela aureoventris Gray, Proc. Zoöl. Soc. London, 1864:55, pl. 8, 1864; Gray, Proc. Zoöl. Soc. London, 1865:115, 1865.
Putorius (Gale) brasiliensis var. aequatorialis Coues, Fur-bearing animals, p. 142, 1877, part? ("merely as a substitute for Gray's [supposedly] preoccupied name," that is, aureoventris).
Mustela affinis costaricensis, Allen, Bull. Amer. Mus. Nat. Hist., 35:101, April 28, 1916 (part).
Mustela macrura, Lönnberg, Arkiv för Zool., 14 (no. 4):11, 1921 (part ?).
Mustela frenata aureoventris, Hall, Carnegie Instit. Washington Publ. 473:110, November 20, 1936; Hall, Physis, 16:175, 1939.
Type.—Probably female, juvenile, skull with skin, no. 64.6.6.3 (formerly 1432a), British Mus. Nat. Hist.; probably Subtropical Life-zone of western Ecuador (locality given as Quito, probably because received from that place).
The skin, once exhibited as a mount, has lost some hair from the back and other parts of the body and is not suitable for remaking into a conventional study specimen. The skull lacks the occiput, basioccipital, premaxillae, upper incisors, two of the lower incisors, all of the canines, premolars 2/2 on both sides, right P3, left p3, and has the left jugal mesially defective. The premolars present are not all fully emerged.
Range.—Pacific coastal regions of Ecuador and Colombia; Subtropical and Tropical life-zones. 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, by presence of p2 and by two rather than one root on P2; from Mustela frenata macrura by Reddish Black, tone 4, plate 344 rather than Chocolate, tone 3, pl. 343 (of Oberthür and Dauthenay), or slightly darker color of upper parts; from M. f. affinis and M. f. meridana by darker color (tone 4 rather than tone 2, Reddish Black of Ober. and Dauth.) of upper parts and larger size of teeth (M1 with length more than 2.4 and breadth more than 4.7; P4 with outside length more than 5.9; length of m1 more than 6.2).
Description.—Unless otherwise stated, information concerning this subspecies is derived from the one referred specimen available, a young male, no. 34677, Amer. Mus. Nat. Hist.
Size.—Male: Total length, 470; length of tail, 160; length of hind foot, 50. Tail 51 per cent as long as head and body.
Female: Not known.
Externals.—Longest facial vibrissae black and reaching beyond ear. Carpal vibrissae reaching to or beyond apical pad of fifth digit; hairiness of foot soles slightly less than shown in figure 20.
Color.—Sides and top of head and neck posteriorly to shoulders black; white facial markings represented by only five white hairs anterior to right ear, one anterior to left ear and three far back on forehead; dark areas at angles of mouth confluent with color of upper parts; tip of tail black; remainder of upper parts near (n) Bay or Reddish Black, tone 4 of Oberthür and Dauthenay, pl. 344; chin whitish; remainder of underparts Warm Buff, deep orange in juvenile, type specimen, according to Gray (1864, pl. 8); color of underparts extending distally on posterior sides of forelegs to wrists but not reaching foot soles and on hind legs to or slightly below knees. Least width of color of underparts equal to 15 per cent of greatest width of color of upper parts. Black tip of tail equal to 27 per cent of length of tail-vertebrae.
In color, no. 34677 is, to me as it was to Allen (1916:101), indistinguishable from the darkest specimens (nos. 178970 and 10112) of M. f. panamensis. Therefore, M. f. aureoventris is one of the two darkest subspecies of weasels.
Skull and teeth.—Male: See measurements and plates [27]-[29]; weight, 4.3 grams; basilar length, 45.8; zygomatic breadth approximately equal to distance between condylar foramen and M1 and to distance between anterior palatine foramen and anterior margin of tympanic bulla; mastoid breadth 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 greater than distance between foramen opticum and anterior margin of tympanic bulla; breadth of rostrum less (at least in young specimen) than length of tympanic bulla; least width of palate seldom if ever greater than length of P4; anterior margin of tympanic bulla as far posterior to foramen ovale as width of three (including I3) upper incisors; height of tympanic bulla not greater than distance from its anterior margin to foramen ovale; length of tympanic bulla more than length of lower molar and premolar tooth-row and shorter than orbitonasal length; anterior margin of masseteric fossa below anterior half of m2.
Skulls of males of M. f. aureoventris, and Mustela frenata macrura from the vicinity of Quito so closely resemble one another as not to be distinguished with the material now available, although the teeth of aureoventris are larger. Comparisons of the skulls of males with those of M. f. meridana and affinis, which are readily distinguishable from those of aureoventris, have been made in the accounts of those subspecies.
Female: Skull of adult unknown.
Remarks.—This subspecies of the Tropical Life-zone, or at least the Subtropical Life-zone, of Ecuador, in certain cranial characters resembles Mustela frenata macrura of the Temperate Life-zone. The two differ markedly in color. Nevertheless, a large number of the specimens collected in Ecuador are intermediate in color as well as in zonal distribution.
The type specimen is young or a juvenile. The measurements of no. 34677 from Gualea indicate an animal similar in size to M. f. affinis. Gray (1864:55) states that the type specimen measures "Length of body and head 6 inches, of tail 4-1/2 inches." The plate (pl. 8) accompanying Gray's original description (loc. cit.) is marked one-half natural size and represents the animal as having a head and body length of eight and one-half inches. One year later Gray (1865:115) gives the measurements of this species as "Length of body and head 12, tail 8 inches." Since he had at this time another specimen, larger than the type specimen (which specimen later, probably, became the type of Mustela affinis Gray), the larger measurements probably were taken from it.
Geographically, and as regards cranial characters, Mustela frenata aureoventris is most closely related to M. f. affinis and to the northern section of M. f. macrura, but in color to M. f. panamensis. M. f. aureoventris and M. f. panamensis are the two darkest-colored subspecies and each occurs in a region of extremely heavy rainfall. There is a skin only, no. 32620, Amer. Mus. Nat. Hist., from Munchique, obtained on June 1, 1911, which is appreciably darker than specimens of M. f. affinis in corresponding pelage and is intermediate between M. f. affinis and M. f. aureoventris in color as it is geographically. The specimen measures 495, 202, 52.