Plates 1, 25, 26, 27 and 30
Mustela tropicalis nicaraguae Allen, Bull. Amer. Mus. Nat. Hist., 35:100, April 28, 1916.
Putorius tropicalis, Allen, Bull. Amer. Mus. Nat. Hist., 24:661, 1908.
Mustela frenata nicaraguae, Hall, Carnegie Instit. Washington Publ. 473:109, November 20, 1936.
Type.—Male, subadult, skull and skin; no. 30754, Amer. Mus. Nat. Hist., Matagalpa, Nicaragua; April 16, 1910; obtained by W. B. Richardson; original no., 712.
The skull (plates [25]-[27], [30]) of the type specimen lacks the entire right zygomatic arch. Otherwise it is complete. The teeth all are present and unbroken. The skin is complete and unfaded but only partly stuffed.
Range.—Honduras and Nicaragua. Altitudinal and zonal limits unknown. See figure [29] on page [221].
Characters for ready recognition.—Differs from M. f. costaricensis and M. f. goldmani in shorter black tip of tail (not more than 35 per cent of length of tail) and lesser width (usually not more than 7 mm.) of tympanic bulla; from M. f. perda in greater extent of color of underparts (22 or more per cent of greatest width of color of upper parts), shorter black tip on tail (not more than 35 per cent as long as tail) and narrower skull, the mastoid breadth in adult males being less than 23.9 and the zygomatic breadth less than 27.
Description.—Size.—Male: Average and extreme measurements of five subadults and one young (four from Matagalpa and one from San Rafel del Norte) are: Total length, 450 (420-480); length of tail, 178 (150-190); length of hind foot, 48 (46-50). Tail averages 65 (extremes 56-69) per cent as long as head and body. Length of hind foot (measurements from dried skins) more than basal length.
Female: Measurements unrecorded.
Externals.—As described in Mustela frenata goldmani, except that hairiness of foot soles (between that shown in figures [20] and [21]) is less, slightly less even than in M. f. perda.
Color.—As described in Mustela frenata goldmani except that: Back near (n) Argus Brown, or Carbon Brown, tone 4 of Oberthür and Dauthenay, pl. 342. Underparts Ochraceous-Buff. Least width of color of underparts, in four males, young, subadult and adult, 24 (extremes 22-26) per cent of greatest width of color of upper parts; the corresponding per cent in one female is 32; black tip of tail, in two subadult males, averaging 29 (extremes, 28-30) per cent of length of tail-vertebrae; corresponding per cent in one female, 36.
Skull and teeth.—Male (based on type specimen, one adult topotype [?] and one subadult from San Rafel del Norte): See measurements and plates [25]-[27], [30]. As described in Mustela frenata perda except that: Weight, 4.2 grams (estimated for adults); basilar length 45.0 (44.8-45.5); interorbital breadth more or less than distance between foramen opticum and anterior margin of tympanic bulla; anterior margin of tympanic bulla as far posterior to foramen ovale as width of four to five upper incisors; length of tympanic bulla not less than length of lower molar and premolar tooth-row; anterior margin of masseteric fossa below anterior margin of m2 or posterior to that tooth.
Female: Skull unknown.
Comparison of the skull of the male with that of M. f. costaricensis is made in the account of that subspecies. As compared with that of M. f. perda, which it most closely resembles, the skull of the male has a narrower, shorter rostrum, lesser interorbital breadth, lesser mastoid and zygomatic breadths and slightly shallower braincase, measured at anterior margin of basioccipital. The tympanic bullae are slightly less projected, at their anterior margins, from the braincase and the squamosal, directly anterior to each, is a little more convex ventrally. The skull of M. f. nicaraguae is, then, slightly shorter than that of M. f. perda and relatively narrower.
Remarks.—When naming this form, Allen (1916:100) characterized it as "Similar to M. tropicalis tropicalis but general coloration much darker and the white face markings somewhat reduced in area." In the sentence preceding the one quoted, Putorius tropicalis perdus was placed as a synonym of Putorius tropicalis tropicalis. M. f. nicaraguae and M. f. perda are nearly alike in color and color pattern but differ in cranial characters. M. f. perda and M. f. tropicalis are widely different in color and more especially in color pattern but differ only slightly in cranial characters. The aggregate difference between perda and nicaraguae is less than that between perda and tropicalis. All three are lowland forms and each is smaller than the adjacent highland forms, namely, M. f. goldmani, macrophonius, perotae and frenata.
The weasels from Honduras definitely are not typical of nicaraguae as it is known from the specimens from Nicaragua itself. The specimens from the state of Tegucigalpa, Honduras, are larger. Some are darker than topotypical nicaraguae. The dorsal outline of the skull is more nearly flat (less convex) in some. In these and several other differential features studied, the average of specimens from Tegucigalpa is intermediate toward goldmani, but everything considered the animals seem best placed with nicaraguae rather than with goldmani or perda, to which latter also, they show some resemblance. With better material from Nicaragua and additional specimens from Salvador (here referred to goldmani) a restudy of all the material now referred to the three races named would be profitable. Aims of this restudy might be to determine if a highland race additional to goldmani should be recognized and if the lowland races perda and nicaraguae differ from one another in the way that the existing specimens indicate.
In the five males from Matagalpa, the narrow white band in front of each ear is confluent with the color of the underparts on one side only in one specimen and on both sides in two specimens. None of these bands is confluent with the white patch between the eyes. A dark spot at the angle of the mouth is present on one side in one specimen. The corresponding area is dark colored in all other specimens but not separated from the color of the upper parts. In the specimen from San Rafel del Norte the white bands are not confluent with the color of the underparts. The female from Mambacho has the mentioned bands confluent with the color of the underparts. This female approaches M. f. costaricensis in the dark color of the upper parts but has more extensive white facial markings than some specimens from much farther north. Like a female seen of M. f. costaricensis, this one has a "frosted" nape but the white hairs on the back of the neck are less numerous than in the female of M. f. costaricensis.
M. f. nicaraguae in typical form, then, is thought of as a small, lowland, tropical subspecies only slightly differentiated from M. f. perda. By reason of its intermediate characters, it constitutes a link between the lowland forms, and the larger animals called M. f. goldmani and M. f. costaricensis.
None of the four skulls from Nicaragua shows signs of infestation of the frontal sinuses by parasites.