Background. The gudgeon is one of the most divergent fish species in Europe. Morphological variability related to sex, size, ecological characters, and geographical distribution are well documented in the literature. Apart from the only few data on the karyotype, chromosome banding patterns of this species have not been studied. Cytogenetic features are very useful tools in taxonomic descriptions of cyprinid species. The aim of this study was to describe and characterise the banding patterns of the gudgeon karyotype. Materials and methods. Cytogenetic examinations of 15 specimens of gudgeon from the upper part of the Odra River, Poland, were carried out. Different chromosome banding techniques: Giemsa staining, C-banding, silver nitrate, chromomycin A3 and DAPI staining were used. Results. The karyotype of gudgeon consisted of 2n = 50 chromosomes, and NF = 98 chromosome arms. Ag-NORs were located on one submeta-subtelocentric chromosome pair and the size polymorphism of NORs was detected. The chromosome sites with G-C rich DNA on one submeta-subtelocentric chromosome pair and heterochromatin block in the centromeric regions were found. Low accumulation of A-T pair rich regions were indicated by DAPI staining. Conclusion. The presently described new chromosomal features of Gobio gobio substantially enhance our knowledge on the taxonomy of this species at cytogenetic level. Jointly with data on morphological- and genetic variability they could be used to determine the phylogeny of the genus Gobio and related species.

chromosome banding patterns, gudgeon, Gobio gobio, fish, karyotype, NOR polymorphism