ABSTRACT
The Order Characiformes is a diverse lineage of ostariophysan fishes presently distributed in the freshwater lakes and rivers of the Neotropics and Africa. Fossil characiforms are also known from Europe. The order contains 19 families and close to 1,700 species, the majority endemic to South American drainages. Aside from a few well-supported subgroups of characiforms, relationships among families are not settled, and the taxonomy of some families, such as the complex Characidae, have undergone considerable recent revision. Most studies place the Citharinoidei (families Citharinidae + Distichodontidae) as the sister group to Characoidei, i.e., all other characiforms. Within the Characoidei, the Anostomoidea (families Anostomidae, Curimatidae, Prochilodontidae and Chilodontidae) is a well-supported lineage. The trans-Atlantic group consisting of the Neotropical families Ctenoluciidae, Erythrinidae, Lebiasinidae and African Hepsetidae is also well supported. Despite lack of resolution, three trans-Atlantic sister clades involving the African Citharinoidei, Alestidae, and Hepsetidae are consistently recovered among higher level studies, although with differing Neotropical sister groups among the published studies. Characiform fossils are known from the 442Late Cretaceous and much of the Cenozoic throughout their modern range, pointing to the deep history of the group. Controversial hypotheses on the early history of characiforms are difficult to test presently.
