Part 62

Putorius arizonensis, Merriam, N. Amer. Fauna, 11:22, figs. 13, 14, June 30, 1896 (part); Stephens, Mammals of California, p. 247, 1906.

Mustela arizonensis, Grinnell and Swarth, Univ. California Publ. Zoöl., 10:376, October 31, 1913; Whitlow and Hall, Univ. California Publ. Zoöl., 40:247, September 30, 1933.

Mustela arizonensis arizonensis, Grinnell, Univ. California Publ. Zoöl., 40:102, September 26, 1933.

Mustela frenata, Boyer, Journ. Mamm., 24:99, February 20, 1943.

Type.--Female, adult, skull and skin; no. 41053, Mus. Vert. Zoöl.; three miles east Baker, White Pine County, Nevada; May 30, 1929; obtained by E. R. Hall and W. C. Russell; original no. 2674, E. R. H.

The skull (plates 33-35) is complete and unbroken. The teeth all are present and entire. The skin is fairly well made. Eight mammae are evident and show the animal to have been nursing young.

Range.--Altitudinally, 700 feet at Wenatchee, Washington, to the highest parts of the mountains of the western United States; Upper Sonoran Life-zone to Arctic Alpine Life-zone; southern British Columbia in the Cascades and territory west to Monashee Mountains, and Nelson, southward in the Cascades of northern Washington, over western Washington, Idaho, Utah, and Nevada to northeastern Arizona and northern New Mexico; westward from the eastern base of the Rocky Mountains in Colorado to the western base of the Sierra Nevada and Cascades of California and to the Cascades of southern Oregon. See figures 29 and 30 on pages 221 and 314.

Characters for ready recognition.--Differs from M. f. oribasus by smaller average size, see measurements; from M. f. longicauda by near (14 n to l) Brussels Brown rather than near (h) Clay Color of the upper parts, and in males by a shallower occiput in which the depth of the skull, exclusive of the sagittal crest, and taken at the anterior border of the basioccipital, amounts to less than 59 per cent of the mastoid breadth; from M. f. alleni by near (14 n to l) Brussels Brown rather than near (h) Clay Color of upper parts in summer; from M. f. neomexicana by near (14 n to l) Brussels Brown rather than Buckthorn Brown color of upper parts, in absence of white frontal spot continuous with color of underparts, in basilar length of less than 46 in males and 40 in females; from M. f. arizonensis by total length averaging more than 375 in males and 330 in females, basilar length averaging more than 41 in males and 36.7 in females; from M. f. inyoensis by absence of white facial markings; from M. f. pulchra by absence of light facial markings, near (14 n to l) Brussels Brown rather than near (16 j) Buckthorn Brown color of upper parts, and lesser size, hind foot less than 40 in females and basilar length averaging less than 46.0 in males; from M. f. xanthogenys by absence of light facial markings and near (14 n to l) Brussels Brown rather than Buckthorn Brown color of upper parts; from M. f. munda by absence of white facial markings, presence of color of underparts on ventral face of proximal third of tail, and hind foot of less than 50 in males; from M. f. saturata by presence of light color of underparts on tail and ankle and in lesser average breadth across mastoid processes of skull (see measurements); from M. f. oregonensis by absence of nasofrontal white patch, presence of light color of underparts on ventral face of tail, and shorter skull, which, relative to its length in males, is deeper through the braincase; from M. f. washingtoni by presence of light color of underparts on ventral face of tail, by skull which in male relative to basilar length is shorter in the preorbital region and wider across the zygomata and mastoid processes, and in female has longer preorbital region and larger bullae (see measurements); from M. f. altifrontalis by lighter colored upper parts which are tones 1 to 3 of Raw Umber, pl. 301, rather than tone 4 of Brownish Drab, pl. 302, of Oberthür and Dauthenay, by Buff-Yellow to Straw Yellow rather than near (14´ a to 16´ c) Ochraceous-Buff color of underparts, by least width of color of underparts amounting to more than 37 per cent of greatest width of color of upper parts, by presence of color of underparts on ventral side of tail and on hind leg over ankle, and by lesser depth of skull through frontal region; from M. f. effera by larger size, males averaging 12-1/2 per cent larger in external measurements, 8 per cent larger in linear measurements of skull, and 22 per cent heavier in weight of skull, total length averaging 400 rather than 360, basilar length averaging 43.6 rather than 40.5.

Description.--Size.--Male: Twenty-one adults from the southern half of the Sierra Nevada of California yield average and extreme measurements as follows: Total length, 400 (356-428); length of tail, 150 (125-178); length of hind foot, 46.1 (42-50). Tail averages 60 per cent as long as head and body. Length of hind foot averaging more than basal length. Corresponding measurements of twelve adults from extreme southern and southwestern Colorado are as follows: 407 (355-431); 150 (133-170); 46.0 (42-49).

Female: Ten adults from the Sierra Nevada of California yield average and extreme measurements as follows: Total length, 349 (336-362); length of tail, 127 (120-133); length of hind foot, 36.3 (32-39). Tail averages 57 per cent as long as head and body. Length of hind foot less than basal length. Corresponding measurements of ten adults from the Rocky Mountains of central Colorado are as follows: 347 (325-375); 123 (111-141); 40 (32-43).

The average differences in external measurements of the two sexes, in the Sierras of California are: Total length, 51; length of tail, 23; length of hind foot, 9.8. Weight of 7 adult males from California is 267 (226-345) grams. Two adult females from there weigh 148 and 115 grams and 3 from White Pine County, Nevada, 134, 122 and 124, giving an average of 129 grams.

Externals.--Longest facial vibrissae black, brown or white (often all three colors in same specimen) and extending beyond ear; carpal vibrissae same color as underparts and extending to apical pad of fifth digit; hairiness of foot-soles (in summer pelage) about as shown in figure 19.

Color.--Upper parts, in summer, near (14 n to l) Brussels Brown or tones 1 to 3 of Raw Umber of Oberthür and Dauthenay, pl. 301, darker on top of head from nose to line connecting posterior margins of ears. Chin and upper lips white. Remainder of underparts Buff-Yellow to Straw Yellow and sometimes Ochraceous-Buff especially in young, and in some adults from southern Colorado. In winter, all white, except tip of tail, or upper parts near (j) Snuff Brown or lighter than Brussels Brown with a smoked effect, and underparts white. Tip of tail at all times black. Color of underparts extends distally on posterior sides of forelegs over toes onto antipalmar faces of feet and wrists, on medial sides of hind legs to ankles, over antiplantar faces of toes, medial third of tarsus and usually over proximal tenth to three-fourths of ventral side of tail. Least width of color of underparts averaging, in a series of twenty males from the southern half of the Sierra Nevada of California, 59 (37-76) per cent of greatest width of color of upper parts. In seven males from southern Colorado corresponding percentages are 55 (37-71). Black tip of tail in series from Sierra Nevada averaging 50 (40-60) mm. long; thus longer than hind foot and averaging 33-1/3 per cent of length of tail-vertebrae.

Skull and teeth.--Male (based on 25 adults, from Sierra Nevada of California): See measurements and plates 19-21; weight, 3.7 (2.9-4.9) grams; basilar length, 43.6 (40.6-46.1); zygomatic breadth more than distance between condylar foramen and M1 (save in four instances) and more than distance between anterior palatine foramen and anterior margin of tympanic bulla (save in two specimens); mastoid breadth more (80 per cent of specimens) or less (20 per cent) than postpalatal length; postorbital breadth less than length of upper premolars and more or less than width of basioccipital measured from medial margin of one foramen lacerum posterior to its opposite; interorbital breadth more or less than distance between foramen opticum and anterior margin of tympanic bulla; breadth of rostrum less than length of tympanic bulla; least width of palate less than medial length of P4 (except in two specimens); anterior margin of tympanic bulla as far posterior to foramen ovale as width of 3 to 5 upper incisors; height of tympanic bulla 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 not carried farther forward than point directly below hypoconid of m1.

Female (based on ten adults from Sierra Nevada of California): See measurements and plates 33-35; weight, 2.2 (1.8-2.4) grams; basilar length, 38.2 (36.7-39.5); zygomatic breadth more (except in one specimen) than distance between condylar foramen and M1 and more (save in two specimens) than distance between anterior palatine foramen and anterior margin of tympanic bulla; postorbital breadth less than length of upper premolars and less than (except in one specimen) width of basioccipital measured from medial margin of one foramen lacerum posterior to its opposite; least width of palate more or less than either outside or inside length of P4 but generally less than inside length; tympanic bulla as far posterior to foramen ovale as width of 3 to 5-1/2 upper incisors; height of tympanic bulla more or less (usually 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 more or less than length of rostrum.

The skull of the female averages 41 per cent lighter than that of the average male.

Compared with the skull of M. f. longicauda, that of both sexes averages smaller in every measurement taken. Males of nevadensis, on the average, relative to the basilar length, are narrower in the interorbital region and across the zygomata but have the orbitonasal length greater. Stated in another way, the rostrum of longicauda appears to be shorter and broader and the zygomata are more expanded. Females of nevadensis, on the average, relative to the basilar length are narrower across the mastoid processes and zygomata and have the braincase deeper at the anterior margin of the basioccipital. Also in nevadensis the mastoid processes do not project so far laterally beyond the braincase, the lambdoidal crest and postorbital processes are less well developed and except in the interparietal region, the temporal ridges hardly meet and they form a sagittal furrow rather than a low sagittal crest which characterizes adult females of longicauda. Each of these differences separating the females of longicauda from those of nevadensis are of the same nature, although not necessarily of the same degree, as those which appear in longicauda with increasing age. The differences mentioned above are readily appreciable when series of specimens are compared. However, none of the differences is of great degree, and most parts of the skulls of the two subspecies are of similar relative proportions. Even so, there is but little overlap in actual size. Comparisons with the skulls of M. f. oribasus, alleni, neomexicana, arizonensis, inyoensis, pulchra, xanthogenys, munda, saturata, oregonensis, washingtoni, altifrontalis, and effera are made in the accounts of those subspecies.

Remarks.--The populations to which the name nevadensis at present is assigned have gone by the name arizonensis since Mearns proposed this name in 1891. Before that time Coues (1877:141) had included individuals of this race under the name Putorius longicauda.

Among the populations here assigned to M. f. nevadensis, there is some geographic variation but it is of lesser degree than in most other species of mammals which range over the same region. Comparison of 20 adult males from the Rocky Mountains of Colorado with 25 adult males from a place as far distant as the Sierra Nevada of California shows that the two populations closely resemble each other. The specimens from Colorado average a trifle wider across the zygomata, have a longer body and therefore relatively shorter tail, and, except in southern Colorado, a slightly longer hind foot. Comparison of ten adult females from each of the two areas reveals that those from Colorado have a markedly longer hind foot, and a tail somewhat shorter relative to the length of the body. The mentioned differences are the only ones found among the great number of points investigated, except that as remarked by Merriam (1896:23) the Sierran animal has the yellow of the underparts reaching farther up under the chin, the underside of the tail on the average is more suffused with yellowish and the white on the upper lip is more extensive. As regards the last mentioned feature, my check of 34 skins from Colorado reveals that the white extends all the way around the upper lip in every specimen but one, whereas in 69 specimens from the Sierra Nevada the white extends all the way around the upper lip in only 39. However, as further remarked by Merriam (loc. cit.), not only this but the other color features are inconstant in addition to being slight. When the occurrence of the dark spots near the angles of the mouth are tabulated, it is found that in 33 Colorado-taken specimens they are absent in 19, faintly indicated in 13, and well developed in 1. In 62 California-taken specimens they are absent in 37, faintly indicated in 20, and well developed in 5.

In northwestern Colorado, southern Wyoming, and possibly through the Bear River Divide into southeastern Idaho, long-tailed weasels here referred to nevadensis approach longicauda in large size and occasionally in other features, more closely than do specimens of nevadensis from most other places in its range. This tendency is thought to be significant for much of the area in question lies in or below the Transition Life-zone, the same life zones in which farther to the eastward true longicauda occurs.

One specimen that illustrates this approach to longicauda is an adult male, no. 2334, collection of E. R. Warren, from 6160 feet, Lay, Routt [now Moffat] County, Colorado. In large size and, relative to the basilar length, shorter rostrum and shorter tympanic bullae, it agrees with longicauda but the darker color and, relative to the basilar length, narrowness of the rostrum, interorbital region, zygomatic expanse and the shallowness through the region of the postorbital processes place it with nevadensis. Of two other specimens from Steamboat Springs, Routt County, a young male, no. 4010, in the collection of E. R. Warren, has a hind foot (50 mm.) as long as in longicauda; and the other, no. 138195, U. S. Nat. Mus., an adult male, agrees well enough in size and proportions with nevadensis but has the coloration typical of longicauda.

From Wyoming, one subadult female, no. 177553, U. S. Nat. Mus., from Garrett, is intermediate in size and coloration but is nearer to nevadensis in these particulars, as it is in all other points considered except size of the molar teeth which are as large as in longicauda and larger than in any female nevadensis from Colorado or California. Another female, an adult, no. 179304, U. S. Nat. Mus., from Lonetree, Wyoming, agrees with longicauda in size of skull. Indeed, ten of seventeen cranial measurements exceed the maximum for Colorado-taken nevadensis. Where differences exist in relative proportions of the skull as expressed in percentages of the basilar length, the specimen approaches nevadensis in 5 instances and longicauda in only 3. The color is intermediate but much nearer that of nevadensis with which the animal agrees also in external measurements. Ten subadults (5 of each sex) from within 12 miles of Laramie (not Fort Laramie) show greater resemblance to nevadensis but definitely approach longicauda. Average external measurements are: , 408, 155, 44; , 361, 134, 40. The two other specimens examined from this general locality, a young female, no. 2711, Mus. Vert. Zoöl., from Fort Bridger, and a subadult female, no. 188377, U. S. Nat. Mus., from Bridger Pass, show no departures from nevadensis of similar age.

The specimens from scattered localities in the Transition Life-zone of northwestern Colorado and southern Wyoming are larger than nevadensis is elsewhere, and also in certain other features resemble longicauda of the plains to the eastward. Everything considered, the animals in question are much more like nevadensis than longicauda. Study of more specimens, especially from Wyoming, might provide grounds for recognizing as a different subspecies the animals in this large area comprising parts of Colorado and Wyoming from which so few specimens now are available. Possibly the name Putorius culbertsoni Coues would apply. Decision on that point will require adequate material from the type locality, Fort Laramie. See discussion of this name under M. f. longicauda.

In southeastern Idaho males are larger than they are at most other places within the range of nevadensis. An average of 7 adults and subadults from Pegram, Montpelier, Springfield, and the vicinity of Pocatello, reveals, when compared with the average of nevadensis from Colorado and that of longicauda from the Great Plains, that this population from southeastern Idaho is nearest to longicauda in linear measurements of the orbitonasal length, mastoid breadth, length of tympanic bullae, and as expressed in percentage of the basilar length, length of tooth-row, breadth of rostrum, and zygomatic breadth. In all other points of size, relative proportions and color, the animals approach nearer to, or actually agree with, nevadensis.

The specimens commented upon clearly show intergradation between nevadensis and longicauda. Similarly, the specimens from Scottsbluff County, Nebraska, here referred to M. f. alleni, by their larger size suggest intergradation of that subspecies with the larger nevadensis-longicauda stock although the approach is more toward longicauda than nevadensis. Between oribasus and nevadensis, however, there is no lack of material showing intergradation. As set forth in the account of oribasus, specimens from Montana are truly intermediate structurally as well as geographically.

Intergradation with washingtoni is shown by specimens from the northern part of the Cascade Range in Chelan and Okanogan counties, Washington. The adult male, U. S. Nat. Mus., no. 235183, from Bald Mountain, is referable to washingtoni on the basis of cranial characters but all the other adult and subadult specimens examined from Chelan and Okanogan counties are nearer nevadensis on the basis of cranial characters. Indeed, some show no approach to washingtoni in cranial characters. As might be expected on geographic grounds, the specimen from Easton, U. S. Nat. Mus., male subadult, no. 116870, shows approach to washingtoni. This is true of the coloration of the hind limbs, small size of the tympanic bullae, and relatively greater length of the preorbital part of the skull. However, the greater width of the light color of the underparts and relatively great breadth across the mastoid processes and zygomatic arches are points of agreement with nevadensis. Similarly, a series of 7 specimens from the Entait River, 20 miles above its mouth, in tone of color is nearer to washingtoni, as is one of the two skulls of adult males in length of the preorbital region. However, in greater breadth of the skull otherwise, and in the relatively great width of the light color of the underparts, the animals are nearer to nevadensis, to which they are here referred. Some of these characters mentioned above in which departure is shown from typical nevadensis are characters that show approach to altifrontalis. This is especially true of the more intense coloration and restriction of the color of the underparts.

Complete intergradation with effera is shown by specimens from southern Oregon. The change from small effera to the larger nevadensis here is gradual; consequently in northeastern California and southern Oregon the size increases gradually to the northward. Specimens showing complete intergradation with oregonensis and saturata are wanting. However, one specimen from Crescent Lake suggests oregonensis in having near (18) apricot yellow underparts such as occur frequently in oregonensis. Also some specimens from northern California approach saturata in having the color of the underparts reduced in the extent to which it reaches out on the under side of the tail. This fact and the consideration that the two races are less different from one another than are other kinds which definitely are known to intergrade leave no doubt but that material from the intervening localities would show complete intergradation.

Intergradation between nevadensis and munda is indicated by specimens from South Yolla Bolly Mountain, Trinity County, which are commented on at greater length in the account of M. f. munda. M. f. inyoensis is so closely related to nevadensis as to leave no doubt that specimens from suitable localities will show actual intergradation. That intergradation occurs directly with the bridled weasel of the interior valleys of California, M. f. xanthogenys, is shown by specimens from along the west-facing flank of the southern part of the Sierra Nevada. Probably intergradation occurs all along the Sierra Nevada on the western slope but specimens are lacking to show this. Weasels are known to occur in the foothill territory and the lesser attention given to this region by mammal collectors than to the higher parts of the mountains may explain the lack of preserved specimens. Individual specimens, here referred to nevadensis, but, showing varying degrees of approach to xanthogenys are as follows: A female from Hume; a male and a female from 8000 feet elevation, Monache Meadows; a male from 9800 feet elevation on the east fork of the Kaweah River; and 7 specimens, probably one family, from one-half mile south of Mineral King, 7850 feet. Of the specimens from 7850 feet, the adult male has no light facial markings and the head is only slightly darker than the back. The adult female has much restricted, light facial markings and the intervening areas are darker than in the male. The five juveniles trapped in the same burrow as the female, each has more extensive light facial markings than the adult female although the area of this varies from only slightly more than in the female to as much as in typical specimens of xanthogenys. Also, the dark color of the head in these five specimens averages darker than in nevadensis and more as in weasels to the southwestward especially latirostra. One of the five juveniles is lighter colored over all of the upper parts than nevadensis and is suggestive of xanthogenys in this respect. Finally, the adult male has on the underparts small spots of ochraceous orange suggestive of latirostra and some individuals of pulchra. No. 30655/42628, U. S. Nat. Mus., taken on Mount Whitney, also shows white facial markings and some other features of the valley-inhabiting xanthogenys. A suggestion of intergradation with arizonensis is furnished by specimens, referred to that race, from Springerville and the Kaibab Plateau. No specimens happen to be available from the region in which intergradation would be expected between nevadensis and neomexicana. Since neomexicana and arizonensis intergrade it is probable that nevadensis also will be found to intergrade with neomexicana. In summary, nevadensis is judged to intergrade with each of the subspecies of Mustela frenata whose range adjoins that of nevadensis.