The systematics of thc genus Lares Cuvier, 1828 in Lake Albert were examined. It is concluded that the inshore form, originally described as Lates albertianus Worthington, 1929 and subsequently as L. niloticus albertianus should be considered as a synonym of L. niloticus (Linné, 1762) but that the offshore form, Lates macrophthalmus Worthington, 1929,warrants full systematic status. It had been relegated to subspecific status, L. niloticus macrophthalmus.
The lectotype for L. macrophthalmus is selected and redescribed. A method by which the species could have evolved, based on suspected differences in partial pressures of oxygen at whichthe blood haemoglobins of the two species become saturated, and on desiccation of the lake in the Pleistocene period, is described.
The diagnostic value of allometry in distinguishing between the two species on a morphologicalbasis is discussed, as is the distribution of the two species in Lake Albert.
The possible significance of interspecific differences in the shape of the caudal peduncle andcaudal fin is considered.