Integrative taxonomy recognises four species within the legume Inga chocoensis (Leguminosae: Caesalpinioideae)

The legume genus Inga is a significant component of Neotropical wet forests. Despite extensive study, the identities and distributions of some species remain contentious. This study focuses on the Inga chocoensis complex, addressing the challenges in species delimitation due to morphological similarity of closely related species. An integrative taxonomic approach was employed, combining morphological and population genetic analyses. Field and herbarium specimens of I. chocoensis s.l. were studied from its entire distribution range. Morphological features were documented, and DNA was extracted and sequenced from 1320 loci using a target-capture approach. Morphological analysis identified consistent differences among groups of specimens of I. chocoensis s.l., suggesting the presence of four distinct species. Key distinguishing features include the number and shape of nectaries on leaflets and the size and shape of fruits. Moreover, a principal component analysis and genetic ancestry admixture analysis of individuals suggest four distinct genetic groups consistent with the species delimited by morphology. Finally, a Mantel test confirms that such genetic differentiation is not due to geographic distance among populations. The four species now delimited are I. chocoensis, I. coprocarpa, and two new species described here, I. calimensis sp. nov. and I. crassinectaria sp. nov. The combination of morphological and genomic data enhanced the accuracy of species delimitation in this clade of recently diverged species. The study underscores the importance of using integrative methods to resolve taxonomic ambiguities in morphologically similar tropical tree species.