José L.O. Mattos & Wilson J.E.M. Costa
Morphological characters and phylogenetic trees generated by analyses of segments of two mitochondrial genes cytochrome b and cytochrome c oxidase I support recognition of three new species of the ‘Geophagus’ brasiliensis species group from coastal basins of northeast Brazil. All new species were diagnosed by exclusive morphological characters and exclusive nucleotide transformations. Geophagus rufomarginatus sp. n., from the Rio Buranhém Basin, is distinguished from all other species of the group by dorsal-fin lappets with red edges, the presence of longitudinal series of small light blue spots between the anal-fin spines and rays, and non-denticulated gill-rakers; it is closely related to G. brasiliensis and G. iporangensis. Geophagus multiocellus sp. n., from the Rio de Contas Basin, is distinguished from all other species of the group by having small pale blue spots with minute bright blue dots at their centres, that are often vertically coalesced to form short bars on the caudal fin. Geophagus santosi sp. n., from the Rio Mariana Basin, is distinguished from all other species of the group by having blue stripes parallel to the dorsal and anal fin rays on their longest portions. Geophagus multiocellus and G. santosi belong to the same clade of G. itapicuruensis. The clade composed by the Rio Paraguaçu Basin species was recovered as the sister group of the other species of the ‘G.’ brasiliensis species group.