Molecular phylogeny of the fishes traditionally referred to Cyprinini sensu stricto (Teleostei: Cypriniformes)

Abstract

Carps (e.g. Koi) of the genus Cyprinus and Crucian carps (e.g. Goldfish) of the genus Carassius are among the most popular freshwater fishes around the world. However, their phylogenetic positions within the subfamily Cyprininae, relationships with their allies (e.g. Procypris, Carassioides), and the monophyly of the group formed by them and their allies, which is referred as the tribe Cyprinini sensu stricto, are far from clear. Historically, the Cyprinini was defined by different people according to whether a cyprinine fish possessed a spinous anal-fin ray (or anal spine), the spine was serrated or not, and occasionally, the number of branched dorsal-fin rays. Some definitions were established without providing any diagnostic characters. In this study, we investigated the monophyly of the tribe Cyprinini sensu stricto, based on four different historical definitions, and explored the phylogenetic relationships of these members in the subfamily Cyprininae. Using five mitochondrial genes as markers, both maximum-likelihood and Bayesian trees were constructed using the optimal partitioning strategy. Both analyses successfully resolved a monophyletic Cyprininae and recovered seven major clades from this subfamily. The diagnosis limiting the tribe Cyprinini sensu stricto to four genera, Cyprinus, Carassius, Carassioides and Procypris, received most support. We propose that only those cyprinines that possess a serrated anal spine and have no < 10 branched dorsal-fin rays should be considered members of this tribe. Cyprinini is sister to the Sinocyclocheilus clade, a group traditionally considered a barbin, and together they form the 'Cyprinini-Sinocyclocheilus' clade. Procypris forms the basal clade of the Cyprinini, whereas species of Carassius and Carassioides locate at the top.