by Gabriel Damasco, Douglas Charles de Burgh Daly, Alberto Vicentini, Paul Van Antwerp Fine
Species delimitation remains a challenge worldwide, but especially in biodiversity hotspots such as the Amazon. Here, we use an integrative taxonomic approach that combines data from morphology, phylogenomics, and leaf spectroscopy to clarify the species limits within the Protium heptaphyllum species complex, which includes subsp. cordatum, subsp. heptaphyllum, and subsp. ulei. A molecular phylogeny indicates that populations of the subsp. cordatum do not belong to the P. heptaphyllum clade, while morphology and NIR data provide additional support for the recognition of a separate taxon. Protium cordatum (Burseraceae) is reinstated at the species rank and described in detail. As circumscribed here, P. cordatum is endemic to white-sand savannas located in the Faro and Tucuruí Districts, Pará State, Brazil, whereas P. heptaphyllum is a dominant and widespread plant lineage found in Amazonia, the Cerrado, and the Brazilian Atlantic Forest. We present an identification key to P. cordatum and closely related lineages and a detailed taxonomic description of P. cordatum, including habitat and distribution, a list and images of diagnostic features. This study demonstrates the importance of using multiple tools to characterize and distinguish plant species in highly diverse tropical regions.