Re-establishment of the genus (Leguminosae, Caesalpinioideae, mimosoid clade): the New World species formerly placed in .

Following recent mimosoid phylogenetic and phylogenomic studies demonstrating the non-monophyly of the genus , we present a new molecular phylogeny focused on the neotropical species in the genus, with much denser taxon sampling than previous studies. Our aims were to test the monophyly of the neotropical section Arthrosamanea, resolve species relationships, and gain insights into the evolution of fruit morphology. We perform a Bayesian phylogenetic analysis of sequences of nuclear internal and external transcribed spacer regions and trace the evolution of fruit dehiscence and lomentiform pods. Our results find further support for the non-monophyly of the genus , and confirm the previously proposed segregation of , , and . All species that were sampled from section Arthrosamanea form a clade that is sister to a clade composed of , , and . We find that lomentiform fruits are independently derived from indehiscent septate fruits in both and section Arthrosamanea. Our results show that morphological adaptations to hydrochory, associated with shifts into seasonally flooded habitats, have occurred several times independently in different geographic areas and different lineages within the ingoid clade. This suggests that environmental conditions have likely played a key role in the evolution of fruit types in and related genera. We resurrect the name to accommodate the species of section Arthrosamanea, except for two species that were not sampled here but have been shown in other studies to be more closely related to other ingoid genera and we restrict the name s.s. to the species from Africa, Madagascar, Asia, Australia, and the Pacific. Twenty-one new nomenclatural combinations in are proposed, including 16 species and 5 infraspecific varietal names. In addition to the type species , the genus has 17 species distributed across tropical regions of the Americas, including the Caribbean. Finally, a new infrageneric classification into five sections is proposed and a distribution map of the species of is presented.