KARYOTYPIC DATA ON 13 SPECIES OF NEARCTIC CARABID BEETLES (COLEOPTERA)

Mitotic and meiotic chromosomes of thirteen Nearctic species of carabi d beetles have been studied. The male haploid chromosome number varies between n=11 + X and n=21 + X. The results obtained allow the followi ng conclusions: (1) The 2n=37 karyotype has been found in eight specie s, one of them belongs to the Limbata Stylifera group, thus corroborat ing its widespread occurrence among the main lineages of the family. ( 2) Data on Amara (Celia) moerens, 2n=37, fit the hypothesis about the ancestrality of this number for the genus Amara. (3) The trend towards low-numbered karyotypes observed in the tribe Lebiini has much progre ssed in Cymindis chevrolati, 2n=24.