Sven O. Kullander: A review of Dicrossus foirni and Dicrossus warzeli, two species of cichlid fishes from the Amazon River basin in Brazil (Teleostei: Cichlidae). Aqua - Journal of Ichthyology, 17(2):. 73-94
Dicrossus warzeli and D. foirni were described with focus on within-species colour pattern variation and aquarium observations. Validity of the two species is confirmed on the basis of wild specimens of D. warzeli from the lower Rio Tapajós between Itaituba (São Luis do Tapajós) and Cururu, and of D. foirni from tributaries of the middle Rio Negro (Rio Marauiá and Rio Padauari). A phylogenetic assessment using colour pattern and fin shape shows that D. foirni and D. warzeli are sister species, and form the sister group of D. filamentosus from the Rio Negro and Rio Orinoco basins and D. maculatus from the central Amazon basin.