1891. Spilogale phenax arizonae Mearns, Bull. Amer. Mus. Nat. Hist., 3:256, June 5, type from near Fort Verde, Yavapai County, Arizona.
1897. Spilogale ambigua Mearns, Preliminary diagnoses of new mammals ... from the Mexican boundary line, p. 3, January 12 [reprinted in Proc. U.S. Nat. Mus., 20:460, December 24, 1897], type from summit of Eagle Cliff Mtn., 2 mi. S of Monument No. 5 of Emory's Survey which, according to Miller (U.S. Nat. Mus. Bull., 128:134, April 29, 1924), is "Eagle Mountain, Chihuahua, Mexico, about four miles south of Dona Ana County, New Mexico."
In 1906 (N. Amer. Fauna, 26:1-55, 10 pls., November 24) A. H. Howell's "Revision of the skunks of the genus Spilogale" was published and the four names listed above were retained by him as applying to four species (not subspecies). His map (op. cit., pl. 1) showing the geographic distribution of the four kinds looks reasonable enough at first inspection and does not indicate any overlapping of the geographic ranges of the species in question, but if a map be made by plotting the localities of occurrence recorded by Howell (op. cit.), for specimens examined by him, a notably different geographic distribution is shown. For one thing the geographic ranges of gracilis, leucoparia, arizonae and ambigua coincide over a considerable part of Arizona. Also, specimens collected in recent years from Arizona and adjoining areas do not readily fit into the "species" recognized by Howell; some specimens are structurally intermediate between two or more of these species and other specimens combine the diagnostic characters ascribed to two or more of the alleged species. For these and other reasons a re-appraisal of the application of the names mentioned above long has been indicated.
Before re-appraising the names it is pertinent to recall that Howell's paper in 1906 on Spilogale was only the second revisionary paper that he prepared. It was prepared by a man who at that time lacked much taxonomic experience, and who held to a morphotype concept. Howell worked under the guidance, in the literal sense, of Dr. C. Hart Merriam. The concept of species and subspecies held by Merriam fortunately was recorded by him (Jour. Mamm., 1:6-9, November 28, 1919). Merriam's reliance on degree of difference and his disregard of intergradation were naturally (and necessarily, we think, in Howell's work in 1906) adopted by Howell. For example, of six specimens from Point Reyes in west-central California, a place less than ten miles from the type locality of Spilogale phenax phenax, Howell (op. cit.:33) assigned one specimen to the subspecies Spilogale phenax latifrons! S. p. latifrons occurs in Oregon and in northern California—no nearer than 200 miles to Point Reyes. Howell's assignment of this specimen to S. p. latifrons was not a lapsus, as persons with the modern (geographic) concept of a subspecies would be likely to suppose. Howell's assignment of the one specimen to S. p. latifrons and the other five specimens to S. p. phenax was intentional, as he told one of us (Hall). He explained that he relied upon the morphological characters of the individual animal instead of upon the morphological characters of a population of animals. To him, therefore, there was nothing inconsistent in his procedure in 1906. Also, variation that was the result of difference in age and variation that was the result of individual deviation were not understood, or at least not taken into account, by Howell in 1906, nor by Merriam in 1890. For example, Merriam selected the most extensively white specimen available to him for the holotype of Spilogale leucoparia. He, and Howell in 1906, used the extensiveness of the white areas of that particular specimen (see fig. 3, pl. 2, N. Amer. Fauna, 26, 1906) as a character diagnostic of the "species" S. leucoparia although each of the authors had available two other specimens of S. leucoparia from the type locality, and all of the other referred specimens in the United States National Museum, that were less extensively white than the holotype. The individual specimen was the primary basis for the species or subspecies and one selected specimen alone often was used in making comparisons between a given named kind and some other species or subspecies. Also, be it remembered, degree of difference, and not presence or absence of intergradation, was the basis on which subspecific versus specific rank was accorded to a named kind of animal. Howell wrote on the labels of some specimens of Spilogale "not typical" when the individuals differed from the type specimen in features that owe their existence to individual variation, and he wrote the same words on the labels of other specimens that had not yet developed mastoidal crests because the animals were not yet adult.
Anyone who examines the specimens that Howell used will do well to bear in mind the circumstances noted above concerning Howell's paper of 1906; otherwise the reasons for Howell's identifications of certain specimens can not be understood.
We have examined and compared the holotypes, and other specimens used by Howell. While doing so we have borne in mind the degree of individual variation well shown by each of several series of specimens (for example, that in six adult males, from the Animas Mountains of New Mexico, recorded by V. Bailey, N. Amer. Fauna, 53:339, 1932) and age variation (for example, that shown in specimens of S. interrupta from Douglas County, Kansas). The degree of each of these kinds of variation, although considerable, is not extraordinary. That is to say, the variations are of approximately the same degree as we previously have ascertained to exist in Mephitis mephitis and in Mustela frenata, two species that are in the same family, Mustelidae, as Spilogale. As a result of our comparisons, we conclude, first that the four names mentioned at the beginning of this account all pertain to one species, and second that the three names S. gracilis, S. p. arizonae and S. ambigua, and probably also S. leucoparia, were based on individual variations in one subspecies. S. gracilis has priority and will apply; the other names are properly to be arranged as synonyms of it, as follows:
1890. Spilogale gracilis Merriam, N. Amer. Fauna, 3:83, September 11.
1890. Spilogale leucoparia Merriam, N. Amer. Fauna, 4:11, October 8.
1891. Spilogale phenax arizonae Mearns, Bull. Amer. Mus. Nat. Hist., 3:256, June 5.
1897. Spilogale ambigua Mearns, Preliminary diagnoses of new mammals ... from the Mexican boundary line, p. 3, January 12.