Current knowledge and new assumptions on the evolutionary history of the African lungfish,Protopterus, based on a review of its fossil record

Lungfish have a large fossil record that started over 400 Ma ago and a relict modern diversity within Australia, Africa and South America. Their study mostly concentrates on their sister‐group relationship with the tetrapod vertebrates, on their early evolution and on the physiology of their air breathing and of the ability of certain species to aestivate. Conversely, little is known about the evolutionary history of modern taxa. In this study, the focus is on the single polytypic extant genus, Protopterus. Four species and seven subspecies are currently present in African freshwater. As fossils, Protopterus are recognized by their heavy tooth plates. Indeed, the review of the diagnostical characters shows that so far we are not able to confidently distinguish fossil species. The fossil record is thus explored through the analysis of the distribution of the genus. A comprehensive scenario for their evolutionary history is built by including also knowledge of the ecology, distribution and phylogeny of modern Protopterus, in the context of the environmental changes that affected Africa over the last 100 Ma. The genus has been present in Africa for at least 100 Ma when the continent separated from South America. Northern Africa might be the cradle for the African lineage, but other regions of Africa cannot be ruled out. During the Paleogene, lungfish disappeared from northern Africa, whereas modern Protopterus arose in a peri‐equatorial area with dispersal from this area late in the Pliocene. This correlates with great environmental change that occured during the last 25 Ma in eastern Africa.