MEIOSIS OF 2 SPECIES OF CACOPSYLLA WITH POLYMORPHIC SEX-CHROMOSOMES IN MALES (HOMOPTERA, PSYLLIDAE)

The karyotype in two species of Cacopsylla (Homoptera, Psyllidae) from four populations was investigated. The males were found to be dimorph ic with respect to their sex chromosome constitution and the automosom e number. Type A (XO) was described for C. sorbi (SUOMALAINEN HALKKA 1 963). Type B (XY) was described for C. mall (MARY ANSKA-NADACHOWSKA et al. 1992 and this paper) and Type C (X(1)X(2)Y) for the two species i n the present work. In Type B and Type C reduction of the autosome num ber was found. The behaviour of the sex chromosome during meiosis was studied. A scheme was proposed indicating how the XO type, through X-a utosome fusion, gave rise to the neo X(1)X(2)Y type.