Phylogenetics of Clusia sect. Criuva (Clusiaceae) unveils a new species, reinstates an old name and clarifies sectional circumscription

Clusia sect. Criuva has long been a taxonomic catch‐all, particularly in the final decades of the 20th century, when misapplications conflated eastern Brazilian taxa with species from the Guiana Shield. We combine herbarium‐based genome skimming, targeted fieldwork, and critical examination of historical literature and types to reassess sectional limits and species boundaries. Phylogenetic analyses (maximum likelihood and Bayesian inference) of ribosomal cistron and plastid genes recover a strongly supported clade comprising the eastern Brazilian species traditionally allied to Clusia sect. Criuva , whereas the Guiana Shield species previously placed in the section fall in other lineages. Within this Brazilian clade we uncover a distinct lineage first detected from an historical herbarium specimen. Subsequent fieldwork confirms it as a narrow inselberg endemic that we describe here as Clusia anaclaudiae sp. nov., with diagnosis, typification and detailed morphology. We also demonstrate that the taxon long treated as C. criuva subsp. parviflora is not conspecific with C. criuva subsp. criuva and, based on nomenclatural priority and lectotypifications, must be referred to C. gaudichaudii . Our synthesis stabilizes the circumscription of C. sect. Criuva , clarifies a century‐old nomenclatural tangle, and demonstrates the value of herbarium genomics coupled with classical taxonomy for discovering and documenting Neotropical plant diversity.