Characiformes is one of the largest teleost assemblages with over 2000 valid species of characins, piranhas, tigerfish, tetras and relatives. They occupy a wide variety of freshwater ecosystems across immense regions in both tropical African and American continents. Four families and roughly 230 species inhabit Africa, from Nile valley to tropical sub-Saharan basins, whereas 20 families and over 1,800 species live in the Neotropical region from southern United States to Argentina and Chile, most of them widespread throughout the Amazon and adjacent basins. African characiforms are represented by four families: Alestidae (19 genera, 116 species), Citharinidae (three genera, eight species), Distichodontidae (17 genera, 104 species), and Hepsetidae (one genus, six species). Previous morphological and molecular studies disagree in the phylogenetic position of each of those families. While morphological phylogenies and an exon-based phylogeny place the suborder Citharinoidei (Citharinidae+Distichodontidae) as the first lineage to diverge within the Characiformes, multilocus and genomic studies have repeatedly found Citharinoidei as sister to remaining characiforms (Characoidei) and Siluriformes. These incongruences reinforce the need to further investigate the early-branch portion of Characiformes. Intrafamilial multilocus studies have demonstrated several instances of non-monophyly of several genera within the Alestidae (e.g., Alestopetersius, Brycinus) and Distichodontidae (e.g., Neolebias, Phago) and the placement of Arnoldichthys and Lepidarchus outside Alestidae. All these studies used a limited species coverage within the three analyzed families: ~45% in Alestidae, ~38% in Citharinidae, ~54% in Distichodontidae; and a molecular interspecific phylogeny is not available for Hepsetidae. Herein, we propose the construction of new phylogenies using a phylogenomic approach of sequence capture of ultraconserved elements (UCEs) through next-gen sequencing. The present study will be fundamental for a better understanding of evolutionary relationships in the early branching of the Characiformes and to test the hypotheses of interfamilial, intergeneric and interspecific relationships and macroevolutionary processes shaping this large teleost lineage.
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