None of the skulls of Mustela africana seen or figured has the nasomaxillary sutures entirely obliterated and the specimens would, judged on this character alone and by analogy with North American species, be regarded as young and subadult. However, the sutures close at what seems to be a later age than in M. frenata and M. erminea. The condition of the mammae in the type specimen of M. stolzmanni and in the specimen from Moyobamba, indicate that they have borne young. North American weasels old enough to bear young lack visible traces of the nasomaxillary sutures. I have examined no skulls of africana with greatly worn teeth and hence cannot say if the sutures are obliterated in advanced age.
If available data be correct, this species is unique within the genus in that the two sexes are of approximately the same actual size and of the same relative proportions in the body and in the skull. There was no difference between individuals said to be of different sexes from Pará, described and figured by Goeldi (1904:61-62, pls. 1, 2). The undoubted female, type specimen of Mustela africana stolzmanni, is as large as the undoubted male, no. 37475, of the same species, but of a different subspecies, from Pará, Brazil. All the specimens of M. a. africana that I have handled are labeled male and those of M. a. stolzmanni female. More material may show that the female is smaller than the male, as is the case in all near relatives of M. africana.
Little has been recorded concerning the habits of this species. Tate (1931:254) states that a live individual which he saw in a cage at Pará had been captured "swimming in the salt water of the estuary about half a mile away from the shore." On the label of the specimen from Moyobamba, there appears: "caught in Willow tree."
Subspecies examined.—All described forms, of which there are two.
Mustela africana africana Desmarest
Tropical Weasel
Plates [28], [29], [30] and [41]
Mustela africana Desmarest, Nouv. Diction. d'Hist. Nat., 19:376, 1818; Cabrera, Bol. Real Soc. Españ. de Hist. Nat., 13:429, November, 1913; Cabrera, Bol. Real Soc. Españ. de Hist. Nat., 14:175, pl. 1, March, 1914.
Putorius (Mustela) brasiliensis paraensis, Goeldi, Zool. Jahrb. abt. f. systematik, geogr. u., Biol., 10:556, pl. 21, September 15, 1897, type from Pará, Brazil, near Pará, Ward of Marco da Legoa, Brazil; Goeldi, Bol. do Mus. Paraense, 3:195 [translation of orig. descr.], August, 1901.
Putorius paraensis, Goeldi, Bol. do Museu Goeldi, 4:61, pls. 1, 2, 1904.
Mustela affinis paraensis, Hollister, Proc. Biol. Soc. Washington, 28:143, July 10, 1914.
Mustela paraensis, Allen, Bull. Amer. Mus. Nat. Hist., 35:105, April 28, 1916; Tate, Journ. Mamm., 12:253, August 24, 1931.
Mustela stolzmanni paraensis, Hall, Carnegie Instit. Washington Publ. 473:111, November 20, 1936; Hall, Physis, 16:167, pl. 1, figs. 1-4, 1939.
Type.—Male, adult or subadult, mounted; no. 848, Paris Museum; from the "Cabinet de Lisbonne 1808," originally from South America as determined from the characters of the animal; probably came from Brazil, and for the present assumed to be from Pará.
On August 25, 1937, the skull was in the mounted skin and the specimen was in the position shown in the figure published by Cabrera (1914, pl. 1). Except for the loss of the distal part of the tail, and fading because of exposure to light, the specimen was in good condition. See also under remarks.
Range.—Known from the south side of the Amazon River, near its mouth at Pará and Cametá, Río Tocantins, in the Tropical Life-zone of Brazil. See figure [29] on page [221].
Characters for ready recognition.—Differs from Mustela frenata, the only other geographically adjacent species of the genus, in presence of median, longitudinal, abdominal stripe of same color as upper parts and naked foot-soles, in absence of p2 and in reduced size of tympanic bullae (see pls. 29 and 30) and from Mustela africana stolzmanni by lighter color of upper parts which although near Chestnut-Brown are in adults 10' l (darker in yg. M. C. Z., no. 30802), instead of 11' n as in M. a. stolzmanni.
Description.—Size.—This is a relatively large weasel. Goeldi (1897:559) gives the total length of the type specimen of his P. b. paraensis, a female, as 520 mm. (495 in the flesh) and, by computation from his figures, the length of the tail as 200 (205 in the flesh). These measurements probably include the hairs on the tip of the tail as probably also do the measurements given of two other specimens (see Goeldi, 1904:62). One of these specimens, a female, measured: Total length, 520; length of tail, 200. The other specimen, a male, measured: Total length, 510; length of tail, 200. The skin of no. 37475, Amer. Mus. Nat. Hist., a male, has the following measurements written on the attached label: Total length, 548; length of tail, 234; length of hind foot, 56. The hairs project 20 mm. beyond the tip of the last vertebra of the tail and probably are included in the measurements of total length and length of tail. Collectors' measurements of a young male from Cametá, and a subadult labeled as male, from Pará Murutucu, are respectively as follows: 500, 430; 210, 190; 50 and 54.
Externals.—Foot-soles naked, except for a few scattered hairs on ventral sides of interdigital membranes; length of claws, measured on concave sides, not more than one and one-fifth times depth of claws measured at bases; carpal vibrissae not extending beyond apical pad of first digit (not beyond hypothenar pad except in one young specimen); longest facial vibrissae not extending to posterior margin of ear; superior genal tuft not found, hairiness of foot-soles as shown in figure [22].
Color.—Upper parts near (10 l) Chestnut-Brown and relatively uniform since tip of tail and muzzle are only slightly darker than remainder; underparts with longitudinal stripe of same color as upper parts extending along median line of belly from throat or breast posteriorly to within 40 to 50 millimeters of anus. Underparts otherwise near (20" a) Olive-Ocher (lips and chin whiter in one young specimen). Color of underparts extends distally on median sides of forelegs to bare foot-soles and on median side of hind legs two-thirds of distance from knee to ankle. Upper lips broadly edged with whitish, which color passes posteriorly below and not touching eye to ventral margin of concha of ear. An inverted, basally broad, V-shaped extension passes upward 4 millimeters, just posterior to the eye.
Skull and teeth.—See measurements (plates [28]-[30]). Male: (based on 3 adult and subadult topotypes and figures and descriptions published by Goeldi, 1897 and 1904.) Weight, 7.0 grams; basilar length, 45.8 (44.6-47.8); skull broad and deep; braincase large, rounded, and much inflated anteriorly; distance from postorbital process to anterior, nasal notch approximately equal to breadth across exoccipital condyles; palatal region wide; tympanic bullae less inflated than in any other species; mastoid bone, laterally, concave; length of upper tooth-rows in adults and subadults less than breadth of palate measured between two outer margins of fourth upper premolars; alveolar distance between C1 and P4 less than length of P4; teeth heavy; medial lobe of M1 only slightly larger than lateral lobe; deuterocone of P4 heavy and often inclined mesially; p2 absent (P2 present above on both sides in only one of seven specimens seen or described); lower jaw heavy; masseteric fossa not extending anteriorly to posterior fourth of talonid of m1; paraconid of m1 low and base of cleft between it and protoconid relatively low on tooth.
Female: No skull examined but from figures published by Goeldi (1904, pl. 2), apparently as described in the male.