Karyotypes of Eight Species of Mexican Rodents (Muridae)

Karyotypes of six species of murid rodents from México are reported for the first time, including: Nyctomys sumichrasti, Peromyscus hylocetes, Peromyscus perfulvus, Peromyscus banderanus, Baiomys musculus, and Neotoma goldmani. The chromosomes of some species clearly suggest affinities within the appropriate taxa. Identity of the sex chromosomes and an apparent automosomal polymorphism are shown for Neotoma alleni. The karyotype of Microtus mexicanus from western México is polymorphic for two pairs of chromosomes and, more importantly, differs significantly from that of presumed M. mexicanus occurring north of México.