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Cytogenetic and DNA content studies of armoured catfishes of the genus Corydoras (Pisces,Siluriformes, Callichthyidae) from the southeast coast of Brazil

Claudio Oliveira^I; Lurdes Foresti Almeida-Toledo^II; Lyria Mori^II; Silvio Almeida Toledo-Filho^II

^IDepartamento de Morfologia, Instituto de Biociências, Universidade Estadual Paulista "Julio de Mesquita Filho", Campus de Botucatu, 18618-000 Botucatu, SP, Brasil. Send correspondence to C.O.
^IIDepartamento de Biologia, Instituto de Biociências-USP, Caixa Postal 11461, 05422-970 São Paulo, SP, Brasil

ABSTRACT

Cytogenetic and DNA content studies were done on six nominal species of Corydoras from the southeast coast of Brazil. The data show that several nominal species present local populations with differences in karyotype of DNA content. There are at least two groups of Corydoras species with similar karyotypic structure in this region: the first composed by C. ehrhardti, C. nattereri and C. paleatus and the second composed of C. barbatus, C. macropterus and C. prionotos. These two groups of species are probably not derived directly from the same ancestral line. The speciation process of Corydoras species from the southeastern coast of Brazil is discussed.

Keywords: Cytogenetic; DNA content; Corydoras; Pisces.

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