Chromosome Numbers and Sex-Determining Systems in Fourteen Species of Chrysomelinae (Coleoptera, Chrysomelidae)

SUMMARYThe analysis of chromosome number and sex-determining system in fourteen species of chrysomelids belonging to four tribes of Chrysomelinae has shown a modal number of 2 n = 24 chromosomes and Xyp sex-system. Gastrophysa polygoni, Mesoplatys cincta (Phaedonini), Gonioctena nivosa, G. linnaeana, G. quinquepunctata (Phyllodectini), Chrysolina coerulans, C. bicolor, Oreina ganglbaueri (Chrysolinini), Paropsis reticulata, Paropsisternd octosignata, P. beata and Chrysophtharta variicollis (Paropsini) have karyotypes of 24 chromosomes while Cyrtonus punctipennis and C. plumbeus (Phaedonini) have 28 chromosomes. In spite that the modal number of the Chrysomelinae seems to be 2 n = 24, the most primitive number for the subfamily is probably 2 n = 20, in agreement with the primitive number of Coleoptera Polyphaga. This number is only encountered in the ancestral genus Timarcha, being all the remaining numbers derived from the primitive one.