New cases of supernumerary chromosomes in characiform fishes

Supernumerary chromosomes were described for five species of Neotropical ch araciform fishes. These extra chromosomes were small, acrocentric and fully heterochromatic in Leporinus friderici from two different localities as we ll as in Leporinus sp., but metacentric and fully heterochromatic in Cyphoc harax modesta and Prochilodus nigricans. In Characidium cf. zebra, this ele ment was small, acrocentric and euchromatic. GC-rich DNA blocks were observ ed in the supernumerary chromosome of Leporinus sp. using chromomycin A(3). The widespread occurrence of these extra chromosomal elements suggests the ir independent origins.