Structural and Numerical Chromosome Diversification in Marine Perciformes (Priacanthidae and Gerreidae)

The Perciformes are characterized by a remarkable chromosomal homogeneity, with a small percentage of its representatives bearing diploid numbers higher or lower than their putative basal number (2n=48). Due to the wide diversity of this group, several families from this order lack cytogenetic reports, such as Gerreidae and Priacanthidae. Chromosomal analyses were carried out in the species Diapterus olithostomus (Gerreidae) and Priacanthus arenatus (Priacanthidae), from Brazilian coast. The karyotype of D. olithostomus is composed by 2n=48 (NF=48), while P. arenatus presented 2n=52 (4st+48a; FN=56). C-banding analysis revealed heterochromatic blocks on centromeric and/or interstitial regions in the 2 species. In D. olithostomus, GC-rich blocks were identified at interstitial position and on ribosomal sites. This species shows the typical karyotype pattern of Perciformes, but the presence of GC-rich interstitial heterochromatin, as well as the presence of 2n>48 in P. arenatus, represents possible autopomorphies. The results report both structural and numerical rearrangements within this order.