CYTOGENETIC AND DNA CONTENT STUDIES OF ARMORED CATFISHES OF THE GENUSCORYDORAS (PISCES, SILURIFORMES, CALLICHTHYIDAE) FROM THE SOUTHEAST COAST OF BRAZIL

Cytogenetic and DNA content studies were done on six nominal species o f Corydoras from the southeast coast of Brazil. The data show that sev eral nominal species present local populations with differences in kar yotype or DNA content. There are at least two groups of Corydoras spec ies with similar karyotypic structure in this region: the first compos ed by C. ehrhardti, C. nattereri and C. paleatus and the second compos ed of C. barbatus, C. macropterus and C. prionotos. These two groups o f species are probably not derived directly from the same ancestral li ne. The speciation process of Corydoras species from the southeastern coast of Brazil is discussed.