PHYSICAL MAPPING OF RDNA GENES IN THE GROUND BEETLE CARABUS AND RELATED GENERA (CARABIDAE, COLEOPTERA)

The major ribosomal DNA (rDNA) loci were localized on meiotic and mito tic chromosomes and in interphase nuclei of 18 ground-beetle species b elonging to three tribes of the supertribe Carabitae by fluorescence i n situ hybridization (FISH), using a PCR amplified 18S rDNA as a probe . Meiotic observations indicate that the 18S rDNA sequences are locate d on the largest autosomal bivalent in 12 species of Carabus, two spec ies of Calosoma (both genera belonging to the tribe Carabini), and thr ee sibling species of Ceroglossus chilensis (tribe Ceroglossini). The data suggest the occurrence of a conservative pattern in these three g enera despite the chromosomal rearrangements that have led to karyotyp es with higher chromosome numbers in Ceroglossus. A different result i s found in Cychrus caraboides (tribe Cychrini), where ribosomal cistro ns are located in two medium-sized autosomal pairs. Further species of Cychrini should be studied for corroborating the occurrence of molecu lar and karyotypical apomorphies in Cychrus with regard to the genera Carabus, Calosoma and Ceroglossus.