First Cytogenetical Studies in Characidium Species (Pisces: Characiformes, Characidiinae).

Fishes of the subfamily Characidiinae are almost unknown from the cytogenetic viewpoint. The mitotic chromosomes of Characidium cf lagosantensis, Characidium sp, Characidium pterostictum, and Characidium cf zebra, are here first described. With 2n=50, the major karyotype structure of all species was very homogeneous. Few differences related to chromosome formulae, and AgNOR bearing chromosomes has been detected. A possible ancestral karyotype and some cytotaxonomic considerations on Characidium genus are discussed.