Circumscribing <i>Chamaecrista</i> section <i>Baseophyllum</i> (Caesalpinioideae, Leguminosae) based on molecular data and morphology

Abstract Advances in phylogenetic knowledge have brought about the need to combine the widely accepted principle of monophyly with morphological diagnosability in proposing new classifications. This is the case of the genus Chamaecrista (Leguminosae, Caesalpinioideae), where the traditional infrageneric classification has not been supported by the genus’s phylogenetic structure. In this study, we used a comprehensively sampled phylogeny to reassess the recently published infrageneric classification of Chamaecrista. We generated 471 sequences from three plastid and two nuclear DNA regions, including entirely new accessions from a fresh specimen of the morphologically puzzling Chamaecrista bucherae from the monospecific sect. Adenophyllum. By conducting ancestral character reconstruction analyses to trace the evolution of morphological traits, we aim to assess the congruence between traditional and alternative classifications of the sect. Baseophyllum. Our findings have unveiled three evolutionarily, geographically, and morphologically coherent lineages, which we reclassify as the three sections: Adenophyllum, Baseophyllum, and Otophyllum. This newly proposed infrageneric classification within Chamaecrista ensures nomenclatural stability and more practical identification, enhancing the challengeable taxonomy of this highly diverse genus.