Reithrodontomys megalotis saturatus Allen and Chapman
Western Harvest Mouse; Spanish, Ratón Orejudo
Reithrodontomys saturatus Allen and Chapman, Bull. Amer. Mus. Nat. Hist., 9:201, June 16, 1897, type from Las Vigas, Veracruz.
Reithrodontomys megalotis saturatus, Howell, N. Amer. Fauna, 36:36, June 5, 1914.
Range.—Northeastern part of state.
Specimens examined, 12: nos. 100202-100212, 100273, from 1 mi. N Zamora, 5,450 ft.
Remarks.—Howell (1914:37) referred nine specimens from Nahuatzin to this race and two from the same place to the subspecies R. m. zacatecae. Our specimens from Zamora agree with topotypes of R. m. saturatus and with specimens of that subspecies from the Valley of México in dark color and large size.
If our specimens of Reithrodontomys megalotis are correctly identified, subspecifically, R. m. zacatecae ranges southward around the western end of the geographic range of R. m. saturatus.
Where R. megalotis and R. fulvescens occur together, we find the skull of the latter to be distinguishable by: a median spine on the posterior border of the hard palate (truncate in R. megalotis); an S-shaped instead of a C-shaped pattern on the worn occlusal face of the last lower molar; and two re-entrant angles, on the lateral side on the worn occlusal surface of the third upper molar, reaching halfway across the tooth whereas in R. megalotis the anterior re-*entrant angle is wanting or extends less than a third of the way across the crown surface of the tooth.
Reithrodontomys megalotis zacatecae Merriam
Western Harvest Mouse; Spanish, Ratón Orejudo
Reithrodontomys megalotis zacatecae Merriam, Proc. Washington Acad. Sci., 3:557, November 29, 1901, type from Valparaiso Mountains, Zacatecas.