Part 3

1815. Sciurus Pennsylvanica Ord, Guthrie's Geog., 2nd Amer. Ed., 2:292. Type locality, western Pennsylvania.

1894. Sciurus carolinensis pennsylvanicus, Rhoads, Appendix of reprint of Ord (supra), p. 19.

1792. Sciurus cinereus Schreber, Saeuget., 4:766. Type locality, eastern United States, probably New York State. (Nec Sciurus cinereus Linnaeus.)

1830. Sciurus leucotis Gapper, Zool. Jour., 5:206. Type locality, region between York and Lake Simcoe, Canada.

1849. Sciurus migratorius Audubon and Bachman, Quad. N. Amer., 1:265 (based on S. leucotis Gapper).

1877. Sciurus carolinensis var. leucotis, J. A. Allen, Monogr. N. Amer. Rodentia, Sciuridae, p. 700 (et auct.).

~Sciurus niger rufiventer~ Geoffroy

Two specimens (36192/48550, a young male with unworn teeth, and 36193/48551, an adult male with much worn teeth, both in the United States Biological Surveys Collection in the National Museum) were recorded by Bailey (N. Amer. Fauna, 25:75, 1905) as Sciurus ludovicianus from Gainesville, Texas. Bailey (loc. cit.) further stated that if the name Sciurus rufiventer Geoffroy proved usable it would apply to the specimens from Gainesville. Since the name rufiventer was revived there would be no question concerning the identity of these specimens had not Lowery and Davis (Occas. Papers, Mus. Zool., Louisiana State Univ., 9:172, 1942) assigned three specimens (not seen by us) to Sciurus niger limitis Baird from a point only thirteen miles northwesterly. Lowery and Davis (loc. cit.) say that their specimens are intergrades (presumably with rufiventer) and Bailey (loc. cit.) noted that his two specimens from Gainesville "are in size and color nearer to ludovicianus [= rufiventer] than to typical limitis." Examination of the two specimens from Gainesville convinces us that Bailey was correct and the specimens therefore are referable to Sciurus niger rufiventer. More in detail, the color agrees with that of rufiventer and differs from that of limitis and from that of darker specimens of Sciurus niger ludovicianus (in the restricted sense used by Lowery and Davis, op. cit.: 104). Also the size is larger than in limitis and as in rufiventer or ludovicianus. Selected measurements of Nos. 36192/48550 and 36193/48551 are, respectively, as follows: Total length, 505, 500; length of tail, 237, 228; length of hind foot, 72, 70; basilar length of Hensel, 48.5, 48.6; zygomatic breadth, 35.1, 36.0; length of nasals, 21.4, 22.3; alveolar length of maxillary tooth-row, 11.8, 11.1; width across posterior tongues of premaxillae, 17.5, 18.4.

~Sciurus variegatoides rigidus~ Peters

Harris (Occas. Papers Mus. Zool., Univ. Michigan, 266:1, June 28, 1933) named Sciurus variegatoides austini with type locality at Las Agujas, Province of Puntarenas, Costa Rica. Later, in his revision of the species Sciurus variegatoides, he (Misc. Publs. Mus. Zool., Univ. Michigan, 38:19, September 7, 1937) referred specimens from Chomes, Costa Rica, to S. v. austini and (op. cit.:24) specimens from Puntarenas, Province of Puntarenas, to S. v. rigidus, an inland subspecies. The geographic arrangement of these referred specimens seemed to warrant a reconsideration of the material. We have examined specimens of S. variegatoides in the Museum of Zoology, University of Michigan, from the following localities in Costa Rica: Puntarenas (62703-62706), Las Agujas (65118 [type of S. v. austini], 59847-59850), Rio Las Agujas (65114-65117), Agua Caliente (66483), Zarcero (75757-75761, 75765), Cartago (67546, 67547), and Esparta (75762-75764). The specimens listed by Harris (op. cit., 1937:19) as from Chomes, in the Museum of Zoology of the University of Michigan, are not now in that museum and we have not seen them.

Harris (op. cit.:19) characterized S. v. austini as differing from S. v. rigidus in having brightly rufous legs (Ochraceous-Orange) in S. v. rigidus and a dorsal coloration resulting from a mixture of shiny black and silver (Ochraceous-Orange mixed with black in S. v. rigidus). We find that in the color of the legs of the paratypes of S. v. austini there is considerable variation ranging from bright rufous in No. 65116 to much darker and duller in No. 59849. In six of the ten specimens of the type series, the color is rufous, but in the other four the color of the legs approaches and overlaps that found in the referred specimens of S. v. rigidus. The color of the dorsum of S. v. austini is also variable. No. 59850, for example, is dark brown and closely resembles No. 75762, from Esparta, which was referred to S. v. rigidus. Further, some specimens referred to S. v. rigidus (67546 and 67547) have the bright-colored legs of S. v. austini and some (75759, for example) have the black-and-silver back of austini. We recognize differences of an average sort between the now-available specimens of the two alleged subspecies, but because of the individual variation that exists, we feel that recognition of two subspecies is not indicated. There is also some variation that is the result of wear and molt and one of us (Kelson) feels that some of the differences are explainable on this basis. Accordingly, we prefer to adopt a more conservative taxonomic arrangement than that of Harris for this group of the Costa Rican squirrels and arrange Sciurus variegatoides austini Harris, 1933, as a synonym of Sciurus variegatoides rigidus Peters, 1863.

~Thomomys bottae alienus~ Goldman

Six specimens (21249-21253, 212706 BS) from Rice, Arizona, were referred by Goldman (Proc. Biol. Soc. Washington, 46:76, April 27, 1933) to the subspecies Thomomys bottae mutabilis Goldman when he proposed that name as new, but these six specimens were not mentioned by him when he later named Thomomys bottae alienus (Jour. Washington Acad. Sci., 28:338, July 15, 1938), to which subspecies the specimens in question might be expected to belong. Examination of the six specimens reveals that they are intergrades between T. b. mutabilis and T. b. alienus but that the specimens more closely resemble the latter. More precisely, slightly larger size of skull, greater ventral inflation of tympanic bullae, and less depressed occipital region ally the specimens with Thomomys bottae alienus, and we identify them as that subspecies. The two subspecies concerned are not so distinct as are most subspecies of Thomomys bottae.

~Thomomys bottae aphrastus~ Elliott

Bailey (N. Amer. Fauna, 39:58, November 15, 1915) referred three specimens from San Antonio, Baja California, to Thomomys bottae nigricans. These specimens have not, to our knowledge, been re-examined subsequently, although the current taxonomic treatment of the pocket gophers of Baja California by Huey (Trans. San Diego Soc. Nat. Hist., 10(4):245-268, 1 map, August 31, 1945) excludes T. b. nigricans from the area of San Antonio. The pertinent specimens are probably Nos. 10810-10812 in the Chicago Natural History Museum. We have examined the specimens and, using the comparative materials listed under the account of T. b. siccovallis, find them to be intermediate in most characters between T. b. aphrastus and T. b. martirensis. Because they more nearly resemble T. b. aphrastus in the weakly-spreading zygomatic arches, we refer the specimens from San Antonio to that subspecies.

~Thomomys bottae jojobae~ Huey

When Huey (Trans. San Diego Soc. Nat. Hist., 10:256, August 31, 1945) named Thomomys bottae jojobae from Sangre de Cristo, Baja California, Mexico, he made no mention of a specimen that Bailey (N. Amer. Fauna, 39:58, November 15, 1915) identified as Thomomys bottae nigricans from La Huerta, which place is approximately eight miles northwest of Sangre de Cristo. From a geographic standpoint, it seemed unlikely that the specimen from La Huerta would be referable to T. b. nigricans. Examination of the specimen (138752 BS) proves it to differ from topotypes of T. b. nigricans and to agree with T. b. jojobae in richer, more rufescent color, especially ventrally, and smaller, slenderer, more delicate skull. The specimen is therefore tentatively referred to Thomomys bottae jojobae. We have not, however, compared it with specimens of Thomomys bottae juarezensis, a subspecies the range of which lies to the east on the summit of the Sierra Juarez.

~Thomomys bottae martirensis~ J. A. Allen

Bailey (N. Amer. Fauna, 39:58, November 15, 1915) referred pocket gophers from Pinon on the west slope of the San Pedro Martir Mountains, Baja California, to the subspecies Thomomys bottae nigricans. The subspecific identity of these animals has now been reinvestigated subsequently, although the locality whence they were obtained is far removed from what is now thought to be the geographic range of T. b. nigricans; further, several other subspecies are known to occur in the intervening area. We have examined the available material from Pinon (13853-13855 BS) and find the specimens to agree with Thomomys bottae martirensis and to differ from T. b. nigricans in lighter color, larger, more ridged and angular skull; proportionately greater mastoidal breadth; narrower occipital shelf; more ventrally produced alveolar ramus of the maxillae; and deeply concave posterior border of the temporal root of the zygomatic arch. These specimens thus constitute the northernmost record of T. b. martirensis known to us.

~Thomomys bottae mohavensis~ Grinnell

Bailey (N. Amer. Fauna, 39:73, November 15, 1915) assigned a series of 7 specimens from Lone Willow Spring, California, to the subspecies Thomomys bottae perpes. This locality lies at the northern edge of the Mohave Desert. Later, Grinnell (Univ. California Publ. Zool., 17:427, April 25, 1918) named the pocket gophers from approximately the eastern half of the Mohave Desert, Thomomys perpallidus [= bottae] mohavensis, but failed to mention the specimens recorded by Bailey, and thus their subspecific identity is in doubt. We find that T. b. mohavensis differs from T. b. perpes in more pallid color (light yellowish as opposed to dark rufescent) larger size, larger and more angular skull, angular (as opposed to more evenly bowed) zygomatic arches, larger and deeper audital bullae, narrower interpterygoid space, and proportionately greater mastoidal breadth. In external measurements, size and angularity of skull, width of interpterygoid space and angularity of the zygomatic arch, the specimens from Lone Willow Spring seem to be intermediate between the two subspecies, but perhaps show more resemblance to T. b. mohavensis. Otherwise, the specimens closely resemble T. b. mohavensis to which they are here referred. The specimens provide a northern marginal record of occurrence for that subspecies.

Other specimens recorded as T. b. perpes by Bailey (loc. cit.) from Grapevine Ranch, California, have also not been mentioned in later publications although, from a geographic standpoint, they might be better referred to either Thomomys bottae pascalis or T. b. mohavensis. Comparison of specimens of T. b. mohavensis and T. b. pascalis from various localities show T. b. pascalis to be larger (including the skull), darker, and to possess a more nearly vertical occipital plane, wider-spread but less angular zygomatic arches, less inflated tympanic bullae, wider braincase (which consequently appears to be less inflated), proportionately longer and slenderer rostrum, and broader nasals distally. Cranially, T. b. pascalis differs from T. b. perpes in essentially the same ways, but to an event greater degree. In color, T. b. pascalis differs from T. b. perpes in being duller, less rufescent.

The series of four specimens, in the U. S. Biological Surveys Collection, from Grapevine Ranch clearly are not referable to T. b. perpes. They do, however, agree with T. b. mohavensis in all essential particulars except that in two of the four specimens the braincase is wider and the nasals are wider distally. This width is evidence of intergradation with T. b. pascalis. Seemingly, then, they are best referred to Thomomys bottae mohavensis.

~Thomomys bottae muralis~ Goldman

When Goldman (Jour. Washington Acad. Sci., 26(3):112, March 15, 1936) described and named this pocket gopher from Arizona, he arranged it as a full species and stated that there is no evidence of intergradation with other named kinds. We have examined the holotype and three topotypes (202579-202582 BS) and compared them with specimens of other kinds of pocket gophers occurring in northern and central Arizona. The muralis gopher is a depauperate form clearly belonging to the bottae group. The characters which Goldman (loc. cit.) set forth as distinguishing muralis from other named kinds are readily apparent and, like Goldman, we see no evidence of intergradation. Nevertheless, the characters which serve to identify the race are, in a general way, those commonly found in populations of depauperate individuals of Thomomys bottae and T. talpoides. The small size, delicate structure, well-inflated braincase, short premaxillary tongues, and strongly recurved upper incisors, often appear in populations existing in inhospitable areas of shallow, unstable soils. For this reason we feel that the relationships of this population are best shown by arranging muralis as a subspecies of Thomomys bottae; the name should stand as Thomomys bottae muralis Goldman.

As far as known, T. b. muralis is completely isolated from other populations of pocket gophers by uninhabitable eroding cliffs. The animals have been found only on isolated terraces in the lower end of Prospect Valley (itself a lateral pocket) within the Grand Canyon of the Colorado River, Hualpai Indian Reservation, Arizona. Consequently it is unlikely that intergradation with other populations could exist at the present time.

In short, in arranging muralis as a subspecies of Thomomys bottae, we are influenced, not by the demonstration of intergradation, but by the degree of morphological differentiation of the population and the probable reasons therefor.

~Thomomys bottae mutabilis~ Goldman