Cytogenetic Studies and Evolutive Considerations on Fishes of the Family Cichlidae (Perciformes) from Parana River (Argentina)

Abstract

Among the Perciformes, Cichlidae represent the more specious group, geographically distributed in Africa, Asia and America. In the present work, 7 species of 5 genera of cichlids from the Paraná River (Misiones, Argentina) were cytogenetically characterized and discussed some aspects of the chromosome evolution. The following chromosome numbers and formulaes: were found for each analyzed species: Crenicichla niederleinii 2n=48 (6 M-SM; 42 ST-A), Crenicichla lepidota 2n=48 (6 M-SM; 42 ST-A), Gymnogeophagus sp. n. 2n=48 (2 M-SM; 46 ST-A), Gymnogeophagus balzanii 2n=48 (2 M-SM; 46 ST-A), Apistogramma trifasciata 2n=46 (16 M-SM; 30 ST-A), Cichlasoma dimerus 2n=48 (8 M-SM; 40 ST-A) and Bujurquina vittata 2n=44 (22 M-SM; 8 ST-A; 14 microchromosomes). The C-positive heterochromatin was observed preferentially in pericentromeric regions of some chromosomes and NORs at the secondary constriction on the first chromosome pair. In B. vittata the microchromosomes are not heterochromatic and the 5th pair shows short arms entirely stained and, in coincidence, the AgNORs appears located at the same region. The results obtained evidence a wide chromosomal variation, either in number and structure that could be integrated with morphological and molecular data in phylogenetic studies.