Karyotypic Variation in Peromyscus boylii from Mexico

Abstract
Results are presented from an extensive survey of karyotypic variation among and within Mexican populations currently assigned to Peromyscus boylii. Considering these and previously published data, the range of autosomal polymorphism within P. boylii (FN = 48–68) would be greater than that known for any other species of Peromyscus and includes karyotypes (FN = 48–51) which are not known to occur in any other species in the genus. Based on karyotypic and distributional factors, we recognize five karyotypic groups which do not directly reflect the current intraspecific taxonomy of P. boylii. The karyotypic differences and the geographic distribution of the various karyotypic groups indicate that more than one species is represented in what is now regarded as P. boylii. The distributions of the forms beatae (FN = 48–54), levipes (FN = 58–60), and rowleyi (FN = 52) are reevaluated in terms of the karyotypic data and it is suggested that each of these represents a distinct species. Due to a paucity of data of boylii-like forms from western México, the taxonomic status and systematic associations of several karyotypic forms from this region remain unresolved.