Cytogenetics of fleas (Siphonaptera: Pulicidae). 1. Rat fleas of the genus Xenopsylla.

Five populations of Xenopsylla cheopis exhibit a chromosome complement of 2n = 17, X1X2Y (male), and 2n = 18, X1X1X2X2 (female). A detailed analysis of populations of X. astia from Bombay and Trivandrum led to the identification of two distinct cytotypes which hybridisation studies indicated were sibling species. These are referred to as X. astia with a diploid chromosome number of 2n = 18, X1X2X3Y (male), and 2n = 20, X1X1X2X2X3X3 (female) and X. prasadii with 2n = 10, X1X2Y1Y2 (male), and 2n = 10 X1X1X2X2 (female). It is proposed that X. prasadii is derived from X. astia through translocation/fusion events since the average total chromosome lengths are remarkably similar in all three species.