Cytogenetics of Seven Species of Dragonflies A Novel Sex Chromosome Determining System in Micrathyria Ungulate

Abstract

More than 80% of the taxonomically described species of Anisoptera (Odonata) belong to the families Libellulidae and Aeshnidae. Here the chromosome complement and male meiotic behaviour of seven species of dragonflies of these families are analyzed. Anax amazili and Coryphaeschna perrensi are 2n = 27, n = 13 + X, which is characteristic of Aeshnidae. Within Libellulidae, Planiplax erythropyga, Micrathyria spuria and M. hesperis have 2n = 25, n = 12 + X, which corresponds to the modal chromosome number of the family. Oligoclada laetitia and M. ungulata, on the other hand, have a reduced chromosome complement (n = 11 + X and n = 10 + X1X2Y, respectively). In Micrathyria ungulata an X1X2Y sex chromosome system is described, and its origin is discussed. This represents a new sex chromosome determining system in the order Odonata