Observations on Hybridization of Three Species of North American Dermacentor Ticks

Female Dermacentor andersoni Stiles confined on the host with male D. variabilis (Say) later produced infertile eggs, whereas the reciprocal cross sometimes yielded progeny of both sexes. Meiotic chromosome pairing, karyokinesis, and cytokinesis in some of these hybrid males suggest various degrees of chromosome homology. Certain morphological characters of the hybrids appeared intermediate while others resembled one parent species more than the other. Hybridization between D. andersoni x D. occidentalis Marx produced no progeny when male D. andersoni mated female D. occidentalis, but the reciprocal cross yielded offspring.