Number and location of rDNA clusters in the superfamilies Tenthredinoidea and Cynipoidea (Hymenoptera): an update

To identify nucleolus organizing regions (NORs), fluorescence in situ hybridization (FISH) with 18S rDNA probe was performed on chromosomes of Tenthredocampestris Linnaeus, 1758 (Tenthredinidae), Argeciliaris (Linnaeus, 1767) (Argidae) (n = 10 in both) and Aulacideahieracii (Bouché, 1834) (Cynipidae) (2n = 20). In all these species, a single pericentromeric rDNA cluster per haploid karyotype was detected. This number of NORs is confirmed as ancestral for the order Hymenoptera.