Pollen morphology and evolutionary history of Sapindales

In Brazil, Sapindales is represented by six families Anacardiaceae, Burseraceae, Meliaceae, Rutaceae, Sapindaceae, and Simaroubaceae. Palynological studies on its members are varied, including few detailed descriptions as well as palynotaxonomic analyses or brief diagnoses in floras or ecological, paleopalynological, or melissopalynological investigations. This study aimed to compile the main pollen characters of Sapindales families occurring in Brazil through a thorough review of the literature including national or foreign taxa and to present new information on the palynology of representatives of the families. Acetolyzed pollen grains from representatives of the six families were also analyzed, measured, and illustrated under light microscope. Unacetolyzed pollen grains were analyzed using scanning electron microscopy. An evolutionary approach to pollen morphology in Sapindales was carried out by mapping and reconstructing the ancestral states of the pollen grains attributes on the existing phylogenetic proposal. Phylogenetic trees were generated by parsimony analysis and used to reconstruct the evolutionary history of each character state of the analyzed taxa. This study represents a first attempt to establish the phylogeny of the order Sapindales using pollen data. Future palynological studies should focus on species not included in the current phylogenetic tree as well as phylogenetic relationships within the nine Sapindales families.