Cytogenetic differences between Peritelus familiaris and Centricnemus leucogrammus (Coleoptera: Curculionidae: Entiminae: Peritelini)

Differences in the karyology of two species, Centricnemus leucogrammus and Peritelus familiaris (Coleoptera: Curculionidae), were investigated in order to elucidate their taxonomic position of the taxa. Previously both species were placed in one genus whereas the latest taxonomic revision puts them in separate genera. Cytogenetic analysis of P. familiaris and C. leucogrammus showed significant differences in karyotype structure and confirmed their present taxonomic status. The diploid set of C. leucogrammus consists of 22 chromosomes with a fundamental number of arms (FN) of 45 and little variation in morphology and length. Peritelus familiaris has 24 chromosomes with FN of 47 and a more diverse karyotype. The karyotype evolution might have occured by centric fissions of autosomes. At pachytene and diplotene in spermatocytes, each chromosome bivalent showed a small band of pericentric heterochromatin. The bands were hardly visible or undetectable in other stages of spermatogenesis, namely mitotic metaphase, diakinesis, metaphase I and II. The nucleolar organizer regions (NORs) were active at premeiotic stages and early meiosis, but invisible at meiotic metaphase I, metaphase II, and mitotic metaphase. These results indicate the usefulness of cytogenetic methods in taxonomic evaluations.