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), Río Las Agujas (65114-65117), Agua Caliente (66483), Zarcéro (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