Key to the species of Eigenmannia from rio Mearim and rio Parnaíba basins

1a. Mouth subterminal, snout pointed in lateral view, posterior nostril at horizontal line between middle and dorsal margin of eye, pectoral-fin margin straight, ii,12–15 pectoral-fin rays....................................... 2

1b. Mouth terminal, snout rounded in lateral view, posterior nostril at horizontal line above dorsal margin of eye, pectoral-fin margin rounded, ii,11–13 pectoral-fin rays ......... Eigenmannia cacuria (rio Parnaíba basin)

2a. Superior midlateral stripe present, 19–23 premaxillary teeth, 20–29 dentary teeth .................................. Eigenmannia bumba (rio Mearim basin)

2b. Superior midlateral stripe absent, 32–34 premaxillary teeth, 35–44 dentary teeth ................................ Eigenmannia robsoni (rio Parnaíba basin)