Genetics and Molecular Biology
On-line version ISSN 1678-4685
KAVALCO, Karine Frehner; BRANDAO, Karina de Oliveira; PAZZA, Rubens and ALMEIDA-TOLEDO, Lurdes Foresti de. Astyanax hastatus Myers, 1928 (Teleostei, Characidae): a new species complex within the genus Astyanax?. Genet. Mol. Biol. [online]. 2009, vol.32, n.3, pp. 477-483. Epub July 03, 2009. ISSN 1678-4685. http://dx.doi.org/10.1590/S1415-47572009005000055.
Four populations of Astyanax hastatus Myers 1928 from the Guapimirim River basin (Rio de Janeiro State) were analyzed and three distinct cytotypes identified. These cytotypes presented 2n = 50 chromosomes, with 4M+8SM+10ST+28A (Cytotype A), 8M+10SM+14ST+18A (Cytotype B), 6M+8SM+4ST+32A (Cytotype C) and scanty heterochromatin, mainly located throughout pericentromeric regions of several chromosomal pairs. No homologies with the As-51 satellite DNA were observed in the three cytotypes, although all of them presented multiple 18S rDNA sites, as detected by both silver nitrate staining and FISH (fluorescent in situ hybridization). The application of the term "species complex" in Astyanax is discussed from a cytotaxonomic viewpoint.
Keywords : Astyanax hastatus; molecular cytogenetics; karyotypic evolution; species complex.