Astyanax hastatus Myers, 1928 (Teleostei, Characidae): a new species complex within the genus Astyanax?

• Main Authors: Karine Frehner Kavalco, Karina de Oliveira Brandão, Rubens Pazza, Lurdes Foresti de Almeida-Toledo
• Format: Article
• Language: English
• Published: Sociedade Brasileira de Genética 2009-01-01
• Series: Genetics and Molecular Biology
• Subjects: Astyanax hastatus; molecular cytogenetics; karyotypic evolution; species complex
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572009000300009

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.