Reinstatement of the genus <i>Psorodendron</i> and related systematic novelties as revealed from phylogenetic analyses of the tribe Amorpheae (Leguminosae, Papilionoideae)

Abstract

The legume tribe Amorpheae comprises eight genera and ca. 240 species exclusive to the New World. We performed parsimony and maximum likelihood phylogenetic analyses based on sequence data from the nuclear gene CNGC4, the chloroplast trnK/matK genes and the nuclear ribosomal ITS regions. Our goal was to infer the generic-level phylogenetic relationships of the tribe with an expanded sampling on Dalea, a genus that comprises nearly 70 % of the species of the tribe. We corroborated that the tribe Amorpheae is formed by the Daleoid clade, comprising Dalea, Marina, and Psorothamnus, and the Amorphoid clade comprising Amorpha, Apoplanesia, Errazurizia, Eysenhardtia, and Parryella. Additionally, Errazurizia resulted polyphyletic given that one of its species (E. rotundata) clusters with Parryella in the most inclusive combined datasets (CNGC4 + ITS, ITS + matK/trnK, and CNGC4 + ITS + matK/trnK); thus, we reinstate the existing name Parryella rotundata to render these two genera as monophyletic. We also corroborate that Psorothamnus is paraphyletic, with species falling into two non-sister subclades, one of them sister to Dalea + Marina, and the other corresponding to the former genus Psorodendron, making imperative the reinstatement of the latter. Dalea is also corroborated as paraphyletic given that D. filiciformis results sister to Marina; thus, this species is transferred to Marina in order to render monophyly of these two genera. Finally, the relationships of the Colombian species remain uncertain due to the incongruence between ITS alone versus matK/trnK and the combined ITS + matK/trnK datasets.