Phylogeography of the genus Epiplatys (Aplocheiloidea: Cyprinodontiformes)

Abstract

There are six major genera of aplocheiloid killifishes endemic to West Africa. Five of these are largely restricted to the two major blocks of rainforest. Two are found within the Eastern rainforest block (Nigeria to the central Congo) while three are found within the Western rainforest block (Sierra Leone to Togo). The sixth genus (Epiplatys) has a range that exceeds that of the combined area of the other five genera. Phylogenetically this genus is related to the Western rainforest taxa. Phylogeographic analysis of this genus suggests that it escaped the confines of the Western block by first expanding into lowland habitats exposed after a sea level drop and then dispersed along coastal habitats to the east. One lineage managed to penetrate the interior of the Eastern rainforest block and one derivative of this lineage penetrated the Congo basin. A second route out of the Western rainforest block was to the north through what is now savannah habitat. The greater phylogeographic range of Epiplatys is hypothesized to be due to retention of ancestral morphology related to a greater adaptability compared to the other five genera.