Testing the phylogenetic hypotheses of Stevardiinae Gill, 1858 in light of new phenotypic data (Teleostei: Characidae)

Abstract

The Stevardiinae are a high diverse subfamily of Characidae, the richest family of Neotropical fishes. Many species are inseminating (internal fertilization) and consequently display diverse morphology of reproductive organs and sperm cells. We test the monophyly and internal relationships of the Stevardiinae through a phylogenetic analysis based on a new set of morphological characters, including reproductive traits, combined with publicly available molecular data. We defined 176 characters from general morphology and primary and secondary sexual characters, coded for 54 species. Analyses were made under parsimony using a broad range of extended implied weighting parameters. Given the different morphological characters we use, this analysis provides additional synapomorphies and an independent test for previous hypotheses based on morphological and combined morphological and molecular datasets. Our final hypothesis is a single most parsimonious tree of 6341 steps obtained under three different weighting schemes. This recovers the monophyly of the tribes Creagrutini, Diapomini, Glandulocaudini, Hemibryconini, Landonini (including Eretmobryconini), Stevardiini, and Xenurobryconini. It also supports the recognition of the monotypic tribe Phenacobryconini. Insemination is ambiguously optimized as present in the common ancestor of Stevardiinae and in the common ancestor of all members of the subfamily except for Landonini. That reconstruction constitutes a novel hypothesis about the evolution of insemination within Characidae.