Integrative taxonomy of Inga chocoensis

The legume genus Inga Mill. 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 Killip ex T.S. Elias 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 sensu lato 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 sensu lato, suggesting the presence of four distinct species. Key distinguishing features included 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 Inga chocoensis, Inga coprocarpa, and two new species described here, Inga calimaensis and Inga crassanectaria. 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.