Format: ORAL

Marco O. O. Pellegrini1, Charles N. Horn2, Stephen D. Hopper3, Matti A. Niissalo4 Rafael F. de Almeida1

1 Royal Botanic Gardens, Kew, UK 2 Newberry College, Department of Sciences and Mathematics, USA 3 University of Western Australia, Centre of Excellence in Natural Resource Management and School of Biological Sciences, Australia 4 Singapore Botanic Gardens, Molecular Biology & Micropropagation, Research & Conservation Branch, Singapore

Commelinales is a small and well-supported monocot order, sister to Zingiberales, and currently includes Commelinaceae, Haemodoraceae, Hanguanaceae, Philydraceae, and Pontederiaceae (arranged in ca. 65 genera and ca. 1,080 species). The order is Pantropical in distribution, reaching temperate areas in some parts of the world, mainly due to the wide distribution of Commelinaceae, Haemodoraceae, and Pontederiaceae. Australasia represents the diversity centres of Haemodoraceae, Hanguanaceae and Philydraceae, and Pontederiaceae has the Neotropics as its diversity centre, especially Brazil. Finally, Commelinaceae possesses two Neotropical (Mexico and Brazil) and two Paleotropical (tropical Africa and Southeast Asia) diversity centres. Despite being strongly recovered as monophyletic by molecular studies, Commelinales lacks any morphological support and circumscription. The order is probably the least studied monocot order from an evolutionary and taxonomic point of view, having suffered the most striking changes in its circumscription between different classification systems (with Commelinaceae being its only consistent member). Based on our combined efforts and extensive herbarium, field, botanical illustration, and morphological studies, we compiled an extensive 570-character morphological matrix, sampling almost a third of the species in the order. Despite the known elevated degree of morphological homoplasy in the order, the topology and relationships we recovered are remarkably congruent with the molecular phylogenetic hypotheses available to date, showing the overlooked potential of large-sized and well-curated morphological datasets. The small degree of incongruence is limited to a few intergeneric and interspecific relationships. Our dataset and analyses recover at least one synapomorphy for each of the recognised genera and families of Commelinales, aside from supporting a revisited infrafamilial classification for all families. Finally, we recover for the first time four morphological synapomorphies for Commelinales, plus a putative fifth, depending on how character states are coded for it.