The Salamanders of Arizona CHARLES H. LOWE, JR. University of Arizona, Tucson The populations of the single species of salamander known to occur in Arizona, Ambystoma tigrinum (Tiger Salamander), have been essentially in uncertain status notwithstanding the recent works of Dunn (1940), Bishop (1943), Stebbins (1951), and Reed (1951). The present confused taxonomic, ecologic, and geographic picture for this area is illustrated by the pecularity that neither Bishop nor Stebbins, the two authors who have ably attempted to map the distribution of the western subspecies of A. tigrinum, has included the geographic posi- tion of the type locality of A. t. nebulosum within the mapped range presented by each of them for that subspecies. Field work by the author during the past few years in Arizona and neighboring states has enabled some clarification of the general problem and the populations of Arizona may now be profitably treated. The populations are considered as comprising three subspecies. Trans- formed individuals of each subspecies have been collected with some individuals from new localities. These, in addition to those at which A. tigrinum has been previously collected, make a total of approximately 30 verifiable localities for this species in Arizona; they are distributed approximately as follows: nebulosum 21, utahense 8, and stebbinsi 1. With the exception of what may be morphologic intermediates (= intergrades), the subspecies are distinctive in 100% of the indi- viduals known for each. Dunn (1940) has correctly emphasized the earlier conclusion of Cope (1867) that in final analysis an intelligible picture of the geographic variation of Ambystorna tigrinum must be primarily based upon color pattern (rather than structural) character- istics of the transformed individuals. The present study may serve as clarifying groundwork for a much needed study of the populations of the entire Colorado River Basin. This is all the more urgent in view of plans of the Department of the Interior and other agencies with regard to the waters of this area, and the rapidly increasing transport and transplanting of larvae of A. tigrinum for fish bait and fish food. Considerably more adequate supplies of fresh and well-preserved specimens are required for such future study. Being as fully important as additional material, the approach to the problem of the geographic variation, ecology, and Transactions of the Kansas Academy of Science, Vol. 58, No. 2, 1955. [237] 238 Transactions Kansas Academy of Science evolution of this group of semi-aquatic vertebrates should take full cognizance of the present and past drainage patterns of the entire basin and adjacent basins (Miller, 1954). Herpetologists who have studied populations of Ambystoma tigrinum in the Far West and have offered their conclusions, seem to have given little consideration to this. A large part of the vagueness that presently surrounds the nature of the variation and the definition of the western subspecies of A. tigrinum, as well as other semi-aquatic and riparian vertebrates of the Inland Southwest, stems in important part from this matter. In Dunn's (1940) major contribution to the study of the tiger salamanders of North America, certain populations of Arizona were necessarily left in uncertain status and others were incorrectly assigned. Unfortunately, he applied Hallowell's (1852) name nebulosum to the populations of A. tigrinum in western Colorado, extreme southwestern Wyoming, most of Utah, and extreme northern Arizona and north- western New Mexico. He diagnosed the populations of this area as "A race without definite markings in adult, dark or blackish . Young with circular yellow spots." This (1) incorrectly evaluated Hallowell's original and clear description of A. nebulosum as a conspicuously yellow spotted salamander (from San Francisco Mountain, Arizona), and (2) is not consistent with the fact that upon complete transformation the basic nature of the color pattern which will typify a given "adult" of A. tigrinum is established regardless of the body length at transfor- mation. Recent studies of living material of small- and large-sized trans- formed individuals from the type locality of nebulosum, San Francisco Mountain, Coconino County, Arizona, and from near Williams, Coconino County, all in the same type of general habitat (Yellow Pine Forest), discloses the excellence of Hallowell's original description of this dorsally yellow spotted and ventrally yellowish patterned form (Fig. 3, B). This sharply and contrastingly patterned yellow and blackish race of the forested strip of the Mogollon Plateau and vicinity, in central Arizona, is entirely different from the A. tigrinum of more extreme northern Arizona, Utah, and adjacent areas. The latter northerly form, to which the name nebulosum has been incorrectly applied, is well illustrated in Bishop (1943:171, nebulosum) and in Stebbins (1951:48 and 165, nebulosum). The great range of variation in color pattern in this particular race is not possible to depict satis- factorily in so few illustrations (Figs. 3 and 4). Fig. 1 shows the general distribution of Hallowell's nebulosum in Arizona. The more northerly subspecies ranging from northwestern The Salamanders of Arizona 239 New Mexico and western Colorado into extreme Arizona and most of Utah (A. t. nebulosum auct.) is accordingly without a name. While the A. tigrinum of this more northerly and relatively large area may comprise more than a single subspecies, it is only possible at this stage of investigation in this area to assign another single name to the complex and consider it as one subspecies approximately as mapped by Stebbins (1951:496, range No. 3). With regard to an available name for this taxon, Dunn (op. cit.) considered Baird and Girard's (1852) clearly described lichenoides from the vicinity of Santa Fe, New Mexico to be synonymous with mavortium. The author has observed large numbers of large-sized living transformed individuals from the vicinity of Santa UTAHENSE I NEBULOSUM X UTAHEN'SE DIT.',"Z"TorAfi'::„t" . Fig. 1. Geographic distribution of the subspecies of Ambystoma tigrinum in Arizona. The small black and white dots represent type localities. 240 Transactions Kansas Academy of Science Fe and concurs with Dunn that they resemble t. mavortium (but appear to the author as distinct therefrom) and certainly are not the same form that Dunn (1940), Bishop (1943), Stebbins (1951), and others have considered as t. nebulosum (Figs. 3 and 4, and also Stebbins, 1951, figs., pp. 48, 165). Among the other names in what has become a relatively long synonomy, there is only one that appears to have been applied to this form. This is A. maculatum Hallowell, 1857, from "New Mexico." It is characterized in the original description as ... color brownish above; tail maculated with black; under parts yellow." Cope (1867:186) characterized it as "Ground olive, with numerous small brown spots." Recent authors (op. cit.) have also characterized this form but invariously have concomitantly applied to it the name nebulosum. It appears evident that Hallowell's A. maculatum is the western form now in question. The type (U.S.N.M. No. 14481) still shows the small dark spots on upper surfaces of the body and tail. The name is a secondary homonym of Ambystoma maculatum Shaw, 60 50 40 30 NUMBER OF SPOTS 20 ,o A STEBBINSI NEBULOSUM MAVORTIUM Fig. 2. Ranges and means of the number of spots on the body and tail of subspecies of A. tigrinum. Data in Table 1. The Salamanders of Arizona 241 1802. It is to be noted that Hallowell, in the period 1852-1857, may have described both of the tiger salamanders occurring in the northern two-thirds of Arizona, one as nebulosum and the other as maculatum. In summary of the nomenclatural problem, (1) the name nebulosum is here restricted to the form which Hallowell (1852 originally described as A. nebulosum from central Arizona, and (2) a different name is A B C Fig. 3. Dorsal aspects of the subspecies of Ambystoma tigrinum occurring in Arizona. A, live A. t. utahense from South Rim of the Grand Canyon, 15.5 miles (by rim road) east Grand Canyon Village, ca. 7,000 ft., Coconino County; B, Me A. t. nebulosum from 2.2 miles (by rd.) west Williams, ca. 6,900 ft., Coconino County; C, preserved A.t. stebbinsi, holotype. Photographs by Geo. M. Bradt, Tucson, Arizona. 242 Transactions Kansas Academy of Science thus necessarily applied to the different subspecies of A. tigrinum occurring in extreme northern Arizona and northwestern New Mexico, western Colorado, extreme southwestern Wyoming, and the greater part of Utah; thus essentially, in the northern half of the Colorado River Basin. A Fig. 4. Ventral aspects of the subspecies of A. tigrinum occurring in Arizona, as shown in Fig. 3 (dorsal aspects). A, A. t. utahense; B, A. t. nebulosum; C, A. t. stebbinsi. Photographs by Geo. M. Bradt. The Salamanders of Arizona 243 The following abbreviations are used: A.N.S.P., Academy of Natural Sciences of Philadelphia; C.H.L., C. H. Lowe, Jr.; M.N.A., Museum of Northern Arizona, Flagstaff; M.V.Z., Museum of Vertebrate Zoology, Berkeley; U.S.N.M., U. S. National Museum. Ambystoma tigrinum nebulosum Hallowell 1852 Ambystoma nebuloium Hallowell, Proc. Acad. Nat. Sci. Phila., vol. 6:209. A Fig. 5. A, dorsal and B, ventral aspects of a preserved specimen of Ambystoma tigrinum mavortium from the Jornada del Muerto, 8.7 miles west and 22.8 miles south New Bingham Post Office, ca. 4,800 ft., Socorro County, New Mexico. Photographs by Geo. M. Bradt. 244 Transactions Kansas Academy of Science 1940 Ambystoma tigrinum nebulosum, part, Dunn, Copeia, No. 3:158. Holotype.—Number 4702, United States National Museum, and Number 1294, Academy of Natural Science of Philadelphia, have been cotypes, collected at San Francisco Mountain, Coconino County, Arizona. U.S.N.M.