Taxonomy and diversity of Marcgraviaceae, north of the São Francisco river, northeast Brazil

This study provides a comprehensive assessment of Marcgraviaceae species diversity north of the São Francisco river in northeastern Brazil, analyzing species richness and distribution patterns across 384 000 km² of phytogeographic domains. Through field collections, herbarium studies (both physical and digital), and detailed morphological analyses, we evaluated the family's diversity. Specimen examinations included in situ observations and morphological descriptions verified against specialized taxonomic literature. We documented four species: Marcgravia coriacea Vahl, Norantea guianensis Aubl., Schwartzia brasiliensis (Choisy) Bedell ex Gir.‐Cañas, and Souroubea guianensis Aubl. Our research establishes new distribution records for M. coriacea , N. guianensis , and S. guianensis within the study area, with N. guianensis representing the first recorded occurrence in Pernambuco state. The highest species richness was found in Atlantic Forest fragments, underscoring their conservation importance. Despite these findings, limited collection efforts and few specialists continue to constrain accurate national‐level assessments of Marcgraviaceae. This study substantially advances understanding of Marcgraviaceae diversity and provides crucial data for conservation policy development, particularly for data‐deficient species.