Chromosomes of the Ragweed Beetle Ophraella communa (Coleoptera: Chrysomelidae) Invaded to Japan

Chromosomes of the ragweed beetle Ophraella communa LeSage (Chrysomelidae: Galerucinae) were studied based on materials collected from four different sites in Tottori Prefecture, Honshu, Japan. Both males and females showed diploid chromosome number (2n) with 34, of which two were sex shromosomes X and Y in males and XX in females. The number is different from 2n = 36 for the same species reported by Petitpierre et al. (1990) but conforms with 2n = 34 by Petitpierre et al. (1993); the both based on the materials from New York State, the United States. The karyotype of the species is presented for the first time. Direction of the evolutionary change of the chromosome number in the genus Opharaella is briefly discussed.