Species concepts, speciation, and taxonomic change in the Lake Malawi mbuna, with special reference to the genus Labeotropheus Ahl 1927 (Perciformes: Cichlidae)

Abstract

While the debate over species concepts and criteria affects all organisms on Earth, no group of organisms demonstrates a need for a consilient, universal species concept better than the haplochromine cichlids of Lake Malawi. These fishes, which are the single greatest radiation of vertebrates on the planet, are a daunting taxonomic puzzle for ichthyologists and evolutionary biologists who try to piece together the history and diversity of these fishes. Accordingly, a number of attempts to apply species concepts to these fishes have been attempted, though rarely with a satisfactory outcome. Focusing on the rock-dwelling cichlids, or mbuna, of Lake Malawi, I evaluate the species concepts that have been applied to these fishes, and conclude that the consilient formulation of the Evolutionary Species Concept is the most appropriate species concept to apply to both our current understanding of the mbuna, and future investigations of mbuna speciation and taxonomy. To further demonstrate the applicability and utility of the Evolutionary Species Concept, I provide a closer examination of the genus Labeotropheus, which has been overlooked in recent taxonomic investigations of the mbuna. While most other mbuna genera have had additional, formally described species added to them, if not additional provisionally named species, Labeotropheus has been ignored, largely due to inappropriately applied species concepts and criteria. I provide a possible research program for the Labeotropheus, based on the consilient formulation of the Evolutionary Species Concept, culminating in the description of new species. © 2009 Springer Science+Business Media B.V.