CYTOGENETICS OF THE AQUARIUM FISHES .2. KARYOTYPIC DIVERSITY OF CHARACID FAMILIES (PISCES, CHARACIDAE)

Somatic karyotypes of four characid fishes usually rearing in acquarium are presented. Family Lebiasinidae: Nannostimus beckfordi has 2n = 42 = 2M + 40A and Nannobrycon eques has 2n = 34 = 34A. Ctenolucius hujeti from the family Ctenoluciidae has 2n = 36 = 26M, SM + 10ST, A, while Metynnis lippicottianus from the family Serrasalmidae shows 2n = 62 = 30M + 30SM, ST + 2A. In the whole the order Characiformes is highly diversive from karyological point of view: chromosomal evolution passed off in the directions of increasing of chromosome numbers (Serrasalmidae) as well as of declining of 2n (Lebiasinidae, Ctenolucidae); the families Anostomidae, Curimatidae, Prochilodontidae, Hemiodontidae and Parodontidae appear to be cytogenetically closed group. Chromosomal evolution in Characiformes consider to be based on pericentric inversions and, in more advanced families, on sex chromosome differentiation, subchromosomal variability and appearance and variability of supernumerary chromosomes. © 1990 Taylor & Francis Group, LLC.