Karyotypes of Some Harvest Mice, Genus Reithrodontomys

Abstract

Karyotypes of six species of harvest mice, representing both the subgenus Reithrodontomys (humulis, sumichrasti, and fulvescens) and the subgenus Aporodon (gracilis, mexicanus, and creper), are described. The karyotype of R. sumichrasti (2n = 40) resembles those previously reported for R. megalotis and R. raviventris, which posses mainly metacentric chromosomes. Reithrodontomys humulis (2n = 51), R. fulvescens (2n = 50), R. gracilis (2n = 52), R. mexicanus (2n = 52), and R. creper (2n = 52) exhibit a large proportion of acrocentric chromosomes. Karyotypic evidence suggests that intrageneric relationships of Reithrodontomys may not be accurately reflected by use of the subgenera Aporodon and Reithrodontomys.