The Subspecies of the Mexican Red-bellied Squirrel, Sciurus aureogaster BY KEITH R. KELSON University of Kansas Publications Museum of Natural History Volume 5, No. 17, pp. 243-250 April 10, 1952 University of Kansas LAWRENCE 1952 UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY Editors: E. Raymond Hall, Chairman, A. Byron Leonard, Edward H. Taylor, Robert W. Wilson Volume 5, No. 17, pp. 243-250 April 10, 1952 UNIVERSITY OF KANSAS Lawrence, Kansas PRINTED BY FERD VOILAND, JR., STATE PRINTER TOPEKA, KANSAS 1952 24-2174 The Subspecies of the Mexican Red-bellied Squirrel, _Sciurus aureogaster_ BY KEITH R. KELSON In his excellent taxonomic treatment of the tree squirrels of Mexico and Central America, Nelson (Proc. Washington Acad. Sci., 1:15-110, 2 pls., May 9, 1899) recognized three subspecies of red-bellied squirrels, _Sciurus aureogaster aureogaster_ F. Cuvier, _Sciurus aureogaster hypopyrrhus_ Wagler, and _Sciurus aureogaster frumentor_ Nelson. In his lists of specimens examined, Nelson (_op. cit._:42 and 44) assigned certain specimens from "mountains near Santo Domingo" and Guichicovi in Chiapas, and Catemaco in Veracruz, to _S. a. aureogaster_, and other specimens from the same localities to _S. a. hypopyrrhus_. I originally attempted to study (identify to subspecies) the series of animals from only three places, but it became evident that a more extensive study was indicated. The locality whence the holotype of _Sciurus aureogaster aureogaster_ was obtained is unknown. Because certain specimens from Altamira, Tamaulipas, closely resemble Cuvier's figure of the type, Nelson (_op. cit._:41) subsequently designated Altamira as the type locality. Miniatitlan, Veracruz, was designated by Nelson as the type locality of _S. a. hypopyrrhus_ because Wagler's description of the type of that subspecies fitted so well certain of Nelson's specimens from that place. _Sciurus a. hypopyrrhus_ was said by Nelson (_op. cit._:43 and 44) to differ from _S. a. aureogaster_ in darker color, thinner pelage, much stiffer and more shining dorsal hairs, slenderer tail with black predominating, larger and proportionately narrower skull with larger auditory bullae, each bulla being "slightly constricted just in front of middle." _Sciurus aureogaster_ varies greatly in intensity of color and in color-pattern. Fully 30 per cent of the specimens examined are in some degree melanistic and approximately 20 per cent of them are completely so. Others are more or less brown; the brown dulls the usually rufous parts. In many specimens this brown is well distributed even in the otherwise grizzled areas; in some specimens it is evenly distributed and in others it is in patches. Indeed, scarcely any two "normally" colored specimens are alike. Typically, the intense rufous color characteristic of the underparts in both _S. a. aureogaster_ and _S. a. hypopyrrhus_ is also present on the costal region and shoulders. Even this distribution of color is highly variable; some specimens (for example No. 23948 KU, from 3 km. E San Andres Tuxtla, Veracruz) show no rufous dorsally and others (for example No. 19307 KU, from 20 km. W Piedras Negras, Veracruz) have the rufous extending over the legs, sides, and almost all of the dorsum from the shoulders to the rump except (in some) for an interrupted median strip of grizzled gray. It is true that specimens from Miniatitlan are darker than those from Altamira, but this seems not to be significant taxonomically, because examination of series from other localities provides no evidence of geographic variation in color except, possibly, in the frequency of melanism. A series of 13 specimens (Univ. Kansas) from 7 and 8 km. WNW Potrero, Veracruz, for example, is quite as dark as topotypes of _S. a. hypopyrrhus_ from Miniatitlan, although the localities of capture are approximately in the center of the geographic range of _S. a. aureogaster_. In short, there seems to be no way to distinguish _S. a. hypopyrrhus_ from _S. a. aureogaster_ on the basis of color. An unusual amount of variation exists, but it seems to occur at random. Fixing type localities of the two subspecies at the places of origin of certain specimens which in color fit the original descriptions is meaningless because selected specimens or series from almost any place in the geographic range of the species would qualify as approximate color-duplicates of the types. My findings agree with those of Nelson in that skulls from Miniatitlan average longer and narrower than those from Altamira, but this seems not to be significant taxonomically because the series from Altamira is, to judge from the material I have seen, somewhat shorter and broader cranially than is "average" for the alleged subspecies _S. a. aureogaster_. For example, series from Metlaltoyuca in Puebla, 3 km. E Axtla in San Luis Potosí, 8 km. NW Potrero and 20 km. NW Piedras Negras in Veracruz, although obtained from localities well within the geographic range of _S. a. aureogaster_ (as outlined by Nelson), all more closely resemble the "topotypes" of _S. a. hypopyrrhus_ in cranial measurements than they do "topotypes" of _S. a. aureogaster_. Conversely, specimens from that part of the range of _S. a. hypopyrrhus_ most remote from the range of _S. a. aureogaster_ (Montecristo, La Venta, and Teapa, all in Tabasco) more closely approximate the Altamiran series in cranial size and proportions than they do the Miniatitlan material. Therefore, my data contradict the statement of Nelson (_loc. cit._) that the skulls of _S. a. hypopyrrhus_ are larger but proportionately narrower than those of _S. a. aureogaster_. The constriction of the auditory bullae alluded to by Nelson as being present in _S. a. hypopyrrhus_ is also present in _S. a. aureogaster_, occurring in both subspecies in varying degrees without correlation with geographic distribution. Actually, the only concrete evidence of geographic variation that I can detect in these animals is a slight increase southwardly in the frequency and degree of melanism, a kind of variation that is unworthy of taxonomic recognition in this species. It seems best, then, to regard the name _Sciurus aureogaster hypopyrrhus_ Wagler as a synonym of _Sciurus aureogaster aureogaster_ F. Cuvier. Nelson (_op. cit._:45) stated that _S. a. frumentor_ "Differs strikingly from typical _aureogaster_ in having well-marked nuchal and rump patches of yellowish brown or rufous brown; the underparts gray or gray washed with rufous; tail heavier and more bushy; pelage softer.... Skull indistinguishable from that of typical _aureogaster_." I have examined 22 specimens from Jico, 7 from Las Vigas (the type locality), and one from 3 km. E Las Vigas, all in Veracruz. These include the type and paratypes of _S. a. frumentor_. Part (probably 7 specimens) of the series from Jico was referred by Nelson (_op. cit._:46) to _S. a. frumentor_ and he thought, or knew, these specimens to have been taken _above_ Jico. The remaining specimens labelled as from Jico were referred to _S. a. aureogaster_. I am unable to find fault with the characterization of _S. a. frumentor_ insofar as color or skull are concerned. I cannot verify to my own satisfaction the presence of "heavier" and bushier tail and softer pelage. The characters considered to be diagnostic of _S. a. frumentor_ are distributed in an interesting geographic pattern the genetic import of which is not wholly clear. One specimen (No. 23945 KU) of the two available from 3 km. SW San Marcos, Veracruz, a locality on the coast approximately 50 miles north of Las Vigas, is indistinguishable from topotypes of _S. a. frumentor_ except for slightly lighter-colored grizzled parts. The second specimen (No. 23946 KU) from the same locality, although a subadult in worn pelage, shows the color and striking dorsal pattern of _S. a. frumentor_ and the ventral color of _S. a. aureogaster_. The dorsal pattern of _S. a. frumentor_ is found also in the three specimens from San Carlos and Plan del Río, Veracruz (Nos. 11082, 11083 and 8278), Chicago Nat. Hist. Mus., respectively. (The two specimens from San Carlos were referred to _S. a. frumentor_ by Elliot, Field Columb. Mus., Zool. Ser., vol. 8, Publ. no. 115:128, February 9, 1907.) Nevertheless, although the essential morphological characters of _S. a. frumentor_ occur sporadically in other populations, the animals from the higher elevations above Jico and Las Vigas are notably homogeneous, differ collectively from surrounding populations, and occupy a logical geographic range. Therefore _S. a. frumentor_ is retained as a tenable subspecies, and the animals from the vicinity of San Marcos, and from San Carlos and Plan del Río are referred to _S. a. aureogaster_. Incidentally, Nelson (_op. cit._:45) remarks that he saw no melanistic specimens of _S. a. frumentor_. This is not strange because melanistic specimens could not be identified anyway. [Illustration: FIG. 1. Geographic distribution of _Sciurus aureogaster_. 1. _Sciurus aureogaster aureogaster._ 2. _Sciurus aureogaster frumentor._] The names, absolute synonyms, and geographic ranges of the two subspecies of _Sciurus aureogaster_ here recognized are as follows: SCIURUS AUREOGASTER AUREOGASTER F. Cuvier 1829. _Sciurus aureogaster_ F. Cuvier, Hist. Nat. Mammiferes, VI, livr. LIX, pl. with text. 1830. _Sciurus rafiventer_ Lichenstein, Abhandl. K. Akad. Wiss., Berlin, p. 116 (1827). 1831. _Sciurus leucogaster_ F. Cuvier, Suppl. d'Hist. Nat. Buffon, pp. 300, 301. 1831. _Sciurus hypopyrrhus_ Wagler, Oken's Isis, pp. 510, 511. 1841. _Sciurus mustelinus_ Audubon and Bachman, Proc. Acad. Nat. Sci. Philadelphia, pp. 100, 101. 1841. _Sciurus ferruginiventris_ Audubon and Bachman, Proc. Acad. Nat. Sci. Philadelphia, p. 101. 1845. _Sciurus ferrugineiventris_ Schinz, Synopsis Mamm., II, p. 14. 1855. _Sciurus hypoxanthus_ (Lichenstein MS) Geoffroy, Voyage de la Venus, Zool. (text), pp. 158, 159 (on labels of squirrels from Berlin Museum, _fide_ Nelson, Proc. Washington Acad. Sci., 1:38, May 9, 1899). 1855. _Sciurus chrysogaster_ Giebel, Saugethiere, p. 650. 1867. _Macroxus aureogaster_ Gray, Ann. and Mag. Nat. Hist., ser. 3, 20:423. 1867. _Sciurus hypopyrrhous_ Gray, Ann. and Mag. Nat. Hist, ser. 3, 20:424. 1867. _Macroxus morio_ Gray, Ann. and Mag. Nat. Hist., ser. 3, 20:424. 1867. _Macroxus maurus_ Gray, Ann. and Mag. Nat. Hist., ser. 3, 20:425. 1887. _Sciurus rufiventris?_ Rovirosa, La Naturaleza, 7:360 (1885-1886). 1897. _Sciurus leucops_ Allen, Bull. Amer. Mus. Nat. Hist., 9:198. 1899. _Sciurus aureogaster hypopyrrhus_ Nelson, Proc. Washington Acad. Sci., 1:42, May 9. _Range._--Eastern slope of Mexico from southern Tamaulipas southward to Tabasco and Chiapas. Marginal localities arranged clockwise beginning with the northernmost station of record are: _Tamaulipas_: Victoria; Altamira; down the coast to _Veracruz_: Coatzocoalcos; inland to _Tabasco_: Montecristo. _Chiapas_: Tumbala. _Oaxaca_: Mountains near Santo Domingo. _Veracruz_: Otatitlan; Orizaba; Jico; Jalapa. _Puebla_: Metlaltoyuca. _Hidalgo_: Sierra Encarnacion. _Querétaro_: Pinal de Amoles. _San Luis Potosí_: Valles. _Tamaulipas_: Forlón. Specimen No. 51383 Chicago Mus. Nat. Hist., labelled as from San Luis Potosí, in the State of the same name, does not represent, I suspect, a natural occurrence of the animal. Possibly the specimen was purchased there in the market, but was actually captured elsewhere. SCIURUS AUREOGASTER FRUMENTOR Nelson 1898. _Sciurus aureogaster frumentor_ Nelson, Proc. Biol. Soc. Washington, 12:154, June 3. _Range._--Higher elevations of the Cofre de Perote. Marginal localities, both in Veracruz, are: Above Las Vigas; Jico. This report is based on the examination of 256 specimens representing the entire known geographic range of the species. I am indebted to H. E. Anthony, Remington Kellogg, C. C. Sanborn, and Stanley P. Young for the privilege of examining specimens in their charge. The study here reported upon was aided by a contract between the Office of Naval Research, department of the Navy, and the University of Kansas (NR 161-791). The specimens in the University of Kansas Museum of Natural History were obtained by field work supported by the Kansas University Endowment Association. _Transmitted December 6, 1951._ 24-2174