Peixes da Esta？？o Ecológica Serra Geral do Tocantins, bacias dos Rios Tocantins e S？o Francisco, com observa？？es sobre as implica？？es biogeográficas das "águas emendadas" dos Rios Sap？o e Galheiros

a preliminary ichthyofaunistic survey conducted at the serra geral de tocantins ecological station (southeastern tocantins and northwest bahia states, central brazil) is presented. this ecological station is situated at the water divide between the rio s？o francisco basin (rio sap？o) and rio tocantins (rio novo, rio balsas, and rio manuel alves da natividade basins). a common headwater ("água emendada") between the rio sap？o and the rio galheiros (the latter a tributary of the rio novo) lies within the station boundaries and is considered in the literature as a potential area of faunistic interchange between the rio s？o francisco and the rio tocantins basins. thirty-five fish species were recorded within the serra geral de tocantins ecological station and at its immediate surroundings, some of which unknown to science and potentially endemic to the area. a total of 111 fish species were regionally recorded (i.e., including fish species recorded at downstream stretches of the rio sap？o and rio novo/do sono, below the ecological station). the cichlid cichlasoma sanctifranciscense is here recorded for the first time for the rio tocantins basin. the occurrence of this species, as well as of the characin astyanax novae in both the rio sap？o and rio novo/do sono basins, are here considered to be the only unequivocal examples of fish species that naturally transposed the water divide between the rio s？o francisco and the rio tocantins basins effected by the common headwater between rio sap？o and rio galheiros.