Three tiger beetle species from the Cicindelini tribe were examined cytogenetically and found to have the following karyotypes: Cicindela argentata, 2n = 18 + X1X2Y/X1X1X2X 2; Cicindela aurulenta, 2n=18 + X1X2X3Y/X1X1X 2X2X3X3 and Cicindela suturalis, 2n = 18 + X1X2X3X4Y/X1X 1X2X2X3X3X4X 4. Fluorescence in situ hybridization (FISH) using a PCR-amplified 18S rDNA fragment as a probe showed the presence of ribosomal clusters in two autosomes in C. argentata, two autosomes and two heterosomes in C. aurulenta and in two heterosomes in C. suturalis (male configuration), revealing two new patterns of rDNA localization. Such results are representative of the cytogenetic variability observed in the species rich genus Cicindela (sensu lato) mainly as regards the localization of rDNA genes and the number and morphology of the heterosomes, in spite of the stability of autosome numbers. Changes in the localization and number of rDNA clusters were independent of changes in the number of sex chromosomes, indicating that several processes might have contributed to the great karyotypic diversity found within this speciose Coleopteran group.
chromosome evolution; Cicindela; multiple sex chromosomes; rDNA localization; tiger beetles
