Electric signal variation among seven blunt-snouted Brienomyrus species (Teleostei: Mormyridae) from a riverine species flock in Gabon, Central Africa

A recently discovered species flock of mormyrid fishes is marked by a striking degree of electric signal diversity among species of rather similar form. We investigated electric organ discharge (EOD) variation in a group of seven, morphologically similar Brienomyrus species within this species flock. All of these forms have blunt snouts. We made quantitative measurements of 25 EOD characters from field recorded signals. Results of principal components analyses using these characters demonstrate that distinct, species-typical EODs are produced by each of the morphologically defined blunt-snouted taxa, consistent with the hypothesis that the EOD plays a role in species recognition. We correctly assigned 30 novel individuals to species on the basis of EOD characters alone using classification functions derived from discriminant function analysis. Landmark-based ordination is a powerful technique for quantifying EOD variation and delimiting species boundaries. This approach will provide an important aid in taxonomic descriptions of new Brienomyrus forms that are still being discovered from the rivers and streams of Gabon.