ABSTRACT
The Cypriniformes is a large group of fishes containing eight families, 280 genera, and over 3,500 species. These fishes are diverse, occupying a wide range of freshwater aquatic habitats in North America, Europe, Asia, India, and Africa. The taxonomy and classification of Cypriniformes is complex and phylogenetic relationships of the included groups are largely unresolved. This lack of resolution stems from the large geographic distribution of taxa, the large number of species, and the difficulty of obtaining specimens of critical taxa. In this chapter we review previous phylogenetic studies and classifications within and among cypriniform families, discuss problematic taxa, and present recent changes to the taxonomy. Recent morphological and molecular studies have provided hypotheses of relationships among included families and forced a reconsideration of the previous five-family classification. Current phylogenetic hypotheses indicate that Cypriniformes can be classified into two major monophyletic groups, Cyprinoidea, containing the Cyprinidae and Cobitoidea, containing Catostomidae, Gyrinocheilidae, Botiidae, Vailantellidae, Cobitidae, Balitoridae, and Nemacheilidae. The Cyprinidae contains a large number of species divided into several subfamilies. There 410is little agreement on the content or relationships among these taxa. Cobitoidea contains fewer species but is also the subject of taxonomic debate. Issues include the relationships of catostomids and gyrinocheilids with respect to the remaining families; species relationships within catostomids; balitorids, cobitids, and nemacheilids; and the phylogenetic position of the cobitids.
