Abstracts Biological Sciences

Interrelationships of five species of kangaroo ants (genus Dipodomys) in Southern California

by Blair Alexander Csuti

Karyotypes were prepared for five species of kangaroo rats (genus Dipodomys) from Southern California. Slides were obtained using bone marrow preparations from animals previously injected with colchicine. A total of eight subspecies were examined: D. agilis agilis and D. a. perplexus (2n=62); D. panamintinus mohavensis (2n= 64); D. heermanni morroensis and D. h. arenae, and D. h. goldmani (2n=64); D. microps microps (2n=60); and D. merriami merriami (2n=52). The karyotype was used as a systematic tool to clarify the distribution and interrelations of these species. The karyotypic distinctness of the morphologically similar D. panamintinus and D. agilis enabled me to demonstrate the presence of D. pantamintinus associated with the Pinyon-Juniper Woodland within the supposed range of D. agilis agilis in the San Gabriel Mountains. D. microps was discovered in an Alkali Sink habitat near Lancaster. These localities represent -range extensions for D. pantamintinus and D. microps. Habitat is considered as a factor in determining distribution. That portion of the range of D. agilis perplexus which extends across the floor of the Antelope Valley as depicted in Hall and Kelson (1959) should be deleted. The similarity of the karyotypes of the broad-faced D. heermanni and D. panamintinus, and the difference of their karyotypes from that of the narrow-faced D. agilis, supports the current division of the heermanni group into broad-faced and narrow-faced subgroups.