Should Kielmeyera tomentosa be reestablished? Implications of leaf anatomy in the Kielmeyera coriacea (Calophyllaceae) species complex

Summary The genus Kielmeyera (Calophyllaceae) includes around 50 species distributed mainly in Brazil. The complex evolutionary history of Kielmeyera is reflected in its great morphological variation and in the difficulty in distinguishing closely related species. Thus, at least three species complexes, namely the K. coriacea , K. petiolaris and K. rubriflora complexes, have been recognised within the genus. Here we assess the variation of leaf anatomical characters across all the taxa included in the Kielmeyera coriacea complex. Our results revealed that seven anatomical characters can be used to identify three distinct groups within this complex. The Kielmeyera coriacea subsp. tomentosa leaf is particularly distinct regarding mesophyll structure, stomata distribution, and size of stomatal chambers. Therefore, we propose to once again accept K. tomentosa at species rank and recognise three species within the complex: K. coriacea , K. grandiflora and K. tomentosa . We demonstrate the enormous potential of evaluating leaf anatomy variation to delimit species in Kielmeyera and in Calophyllaceae.