Phylogenomics, morphological evolution, and taxonomic revision of <i>Spirotropis</i>, a newly delimited legume genus of ecologically dominant Amazonian tree species

Abstract Spirotropis (Leguminosae, Papilionoideae) is a Neotropical genus of trees that has long remained circumscribed to just one species, S. longifolia . Evidence from previous molecular phylogenetic analyses of nuclear and plastid loci and morphological features supports expanding its circumscription to encompass species from the polyphyletic Clathrotropis s.l. that are widely distributed in the Amazonian forests. Here, we reassess the evolutionary relationships of Spirotropis and Clathrotropis s.l. based on a new plastome‐wide phylogenomic analysis of the genistoid legumes. The evolutionary histories of selected morphological characters were estimated through Bayesian stochastic mapping over a robust phylogeny of the Ormosieae clade in order to investigate synapomorphies that define an expanded concept of Spirotropis . The newly circumscribed genus Spirotropis was recovered as a well‐supported monophyletic group comprising five species: the type S. longifolia , three species added from Clathrotropis s.str. ( S. nitida , S. paradoxa , S. rosea ) and the newly described S. fusca endemic to Venezuela. These species are represented by trees with fragrant flowers and spirally twisted keel petals that grow from tropical lowland rain forests, including seasonally flooded forests, to montane forests. In this study, we present identification keys for the Ormosieae genera and the Spirotropis species, in addition to full taxonomic descriptions, illustrations, maps of geographic distribution, and comments on the morphological distinctiveness, nomenclature, and ecology of each species.