| Summary: | The subtribe Ditaxinae in the plant family Euphorbiaceae is composed of five genera (<i>Argythamnia</i>, <i>Caperonia</i>, <i>Chiropetalum</i>, <i>Ditaxis</i> and <i>Philyra</i>) and approximately 120 species of perennial herbs (rarely annual) to treelets. The subtribe is distributed throughout the Americas, with the exception of <i>Caperonia</i>, which also occurs in tropical Africa and Madagascar. Under the current classification, Ditaxinae includes genera with a questionable morphology-based taxonomy, especially <i>Argythamnia</i>, <i>Chiropetalum</i> and <i>Ditaxis</i>. Moreover, phylogenetic relationships among genera are largely unexplored, with previous works sampling <10% of taxa, showing Ditaxinae as paraphyletic. In this study, we inferred the phylogenetic relationships within Ditaxinae and related taxa using a dataset of nuclear (ETS, ITS) and plastid (<i>pet</i>D, <i>trn</i>LF, <i>trn</i>TL) DNA sequences and a wide taxon sampling (60%). We confirmed the paraphyly of Ditaxinae and <i>Ditaxis</i>, both with high support. Following our phylogenetic results, we combined <i>Ditaxis</i> in <i>Argythamnia</i> and upgraded Ditaxinae to the tribe level (Ditaxeae). We also established and described the tribe Caperonieae based on <i>Caperonia</i>, and transferred <i>Philyra</i> to the tribe Adelieae, along with <i>Adelia</i>, <i>Garciadelia</i>, <i>Lasiocroton</i> and <i>Leucocroton</i>. Finally, we discuss the main morphological synapomorphies for the genera and tribes and provide a taxonomic treatment, including all species recognized under each genus.
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