Format: ORAL

Matheus Colli-Silva1, Oscar Alejandro Prez-Escobar1, Carlos D.M. Ferreira2, Maria T.R. Costa2, Samuele Gerace2, Thales Silva-Coutinho3, Vania Nobuko Yoshikawa4,5, Higor Antonio-Domingues1, Rebeca Hernndez-Gutirrez6, Martin Cheek1, Mark W. Chase1, Michael F. Fay1, William S. Alverson7, Massimo Bovini2, Laurence J. Dorr8, William J. Baker1and Alexandre Antonelli1,9,10,11

1 Royal Botanic Gardens, Kew, Richmond, Surrey, United Kingdom. 2 Instituto de Pesquisas Jardim Botânico do Rio de Janeiro, Diretoria de Pesquisas, Rio de Janeiro, Rio de Janeiro, Brazil. 3 Instituto de Biociências, Universidade Federal do Mato Grosso, Cuiabá, Mato Grosso, Brazil. 4 Laboratório de Sistemática Vegetal, Núcleo de Ciências Ambientais, Programa de Pós-Graduação em Biotecnologia, Universidade de Mogi das Cruzes, Mogi das Cruzes, São Paulo, Brazil. 5 Department of Botany, Institute of Biosciences, University of São Paulo, São Paulo, Brazil (Present affiliation). 6 Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, California, USA. 7 WIS Herbarium, University of Wisconsin-Madison, Madison, Wisconsin, USA. 8 Department of Botany, National Museum of Natural History, Smithsonian Institution, Washington DC, USA. 9 Gothenburg Global Biodiversity Centre, Box 461, SE 40530, Gothenburg, Sweden. 10 Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China. 11 Department of Biology, University of Oxford, Oxford, United Kingdom.

The Malvales, a diverse order of flowering plants spanning various global biomes, boasts significant species diversity and morphological variability. Despite its ecological and economic importance, Malvales classification has been largely neglected since the late 1990s. This study addresses this gap by revisiting Malvales classification, emphasizing its largest family Malvaceae. By integrating molecular and morphological datasets, our primary goal is to map key traits for classification onto an extensive phylogeny and reassess taxonomic boundaries as necessary. This investigation enhances our evolutionary understanding of Malvales,bringingprovidingvaluable insights for a more contemporary taxonomy. We generated a molecular dataset based on 196 nuclear genes for 188 genera within Malvales, includinggenera fromall recognized families and subfamilies, almost all tribes, and all subtribes. Phylogenetic trees were inferred using maximum-likelihood and a coalescence approach to reconcile conflicts. A morphological matrix with 52 characters relevantfortosuprageneric classification was compiled to identify diagnostic features within specific clades. Character state distributions were mapped onto the final phylogenetic topology to aid the searchoffordiagnostic featuresforofsuprageneric taxa. Phylogenetic relationships and monophyly for most groups aligned with prior research. Significant variations in diagnostic morphological traits were observed across clades, including growth forms, leaf structures, pollen types,flowerfloralattributes, and fruit/seeds. Incongruities in relationships among some Malvales families and within well-supported Malvaceae clades were attributed to discrepancies observed in gene trees. For Malvaceae, uncertainties in basal Malvoideae were resolved. Incongruities among nuclear loci, while not impacting clade definitions, suggest caution in interpreting the current Malvaceae classification. We propose maintaining Malvaceaesensu latoand introducing two new subfamilies (Matisioideae and Durionoideae) forseveraltropical genera. Pollen characteristics define Malvoideae asamonophyleticsubfamily. Four new tribes within Malvoideae improve taxonomic placement for genera previously of uncertain classification, aligning with updated findings.