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.
A cytogenetic study of bisexual species belonging to the genera Cirrorhynchus, Dodecastichus and Otiorhynchus is presented in order to confirm their taxonomic position. The karyotype characterization was accomplished by an analysis of mitotic and meiotic chromosomes after differential staining, namely by C-banding, silver impregnation, DAPI and CMA3. A review of the cytogenetic data for the tribe Otiorhynchini contributed to knowledge of chromosomal evolution in this group. An investigation of five of the species studied showed some similarities such as a sex chromosome system of "parachute type" (Xyp), the presence of 10 autosomal bivalents (2n = 22) and heterochromatin localized around centromeres. These observations are similar to those already described for Otiorhynchini species, and confirm the karyological conservatism of this weevil group. In contrast, another species Cirrorhynchus kelecsenyi has an additional four autosomal bivalents (n% = 14 + Xyp, 2n = 30), which differs considerably from the chromosomal homogeneity of the other genera. Karyotypic evolution in this species was achieved most probably by increasing the number of chromosomes by centric fissions, resulting in variation in the number of acrocentric chromosomes. DAPI-positive and CMA3-negative reactions of heterochromatic DNA in all the species studied suggest that it has an AT-rich composition. Impregnating chromosomes with silver nitrate reveals NORs on one pair of autosomes, and probably argentophilic material in the interspace between the X and y sex chromosomes. The karyological findings support the taxonomical revision of Otiorhynchini based on morphological characters.