title: Astyanax hastatus Myers, 1928 (Teleostei, Characidae): A new species complex within the genus Astyanax?
abstract: 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.
authors.affiliation: Universidade Federal de Viçosa, Campus de Rio Paranaíba, Rio Paranaíba, MG Brazil.
authors.forename: Karine Frehner
authors.initials: KF
authors.lastname: Kavalco
authors.forename: Karina
authors.initials: K
authors.lastname: de Oliveira Brandão
authors.forename: Rubens
authors.initials: R
authors.lastname: Pazza
authors.forename: Lurdes Foresti
authors.initials: LF
authors.lastname: de Almeida-Toledo