Format: ORAL

Thiago Cobra e Monteiro^1*,†, Higor Antonio-Domingues^2*,†, João R.V. Iganci³, Renan P. Campos¹, Gwilym P. Lewis², Mohammad Vatanparast², Bente B. Klitgaard², Federico Luebert⁴, Flávia Pezzini⁵, Rafaela J. Trad⁵, Marcus Falcão⁶, Vidal F. Mansano⁶, Carolina M. Siniscalchi⁷, Ryan Folk⁷, Silvia T. S. Miotto⁸, Cynthia F. P. da Luz⁹, Mônica L. Rossi¹⁰, Rafael F. de Almeida², Adriana Pinheiro-Martinelli¹⁰, Ana Paula Fortuna Perez^1*

1 Universidade Estadual Paulista, Botucatu, São Paulo, Brazil 2 Royal Botanic Gardens, Kew, United Kingdom 3 Universidade Federal de Pelotas, Rio Grande do Sul, Brazil 4 Universidad de Chile, Santiago, Chile 5 Royal Botanic Garden Edinburgh, United Kingdom 6 Instituto de Pesquisas do Jardim Botânico do Rio de Janeiro, Brazil 7 Mississippi State University, United States of America 8 Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil 6 Instituto de Pesquisas do Jardim Botânico do Rio de Janeiro, Brazil 7 Mississippi State University, United States of America 8 Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil 9 Instituto de Pesquisas Ambientais, São Paulo, Brazil, 10 Universidade de São Paulo, Esalq, Piracicaba, Brazil

The Adesmia clade encompasses five genera: Adesmia, Amicia, Nissolia, Poiretia and Zornia, and it is sister to the Pterocarpus and Dalbergia clades (Dalbergieae). The clade arose ca. 35 Ma ago, and all genera are monophyletic, but the infrageneric divisions of the two largest genera (Adesmia and Zornia) are paraphyletic. Adesmia is the largest genus of the clade with over 200 species almost exclusively distributed along the western South American Dry Diagonal (wSADD), which stretches from Patagonia to the Peruvian Desert and contains some of the driest environments on Earth. While the ancestor of Adesmia is associated with the wSADD, the ancestor of the clade (i.e., Amicia, Poiretia, and Zornia, ca. 100 species) is associated with the eastern South American Dry Diagonal (eSADD). The eSADD comprises the Chaco, Cerrado, and Caatinga domains, and is marked by a seasonal precipitation regime. Sister to the other genera within the Adesmia clade, Nissolia has a distinct distribution within Seasonal Dry Tropical Forests. Both vegetative and reproductive characters exclusive to this clade may have impacted the group diversification in the dry diagonals of South America. There are several potential functional traits linked to the occupation, diversification, and maintenance of Adesmia clade species in dry environments. These include a variety of secretory structures, growth forms and life history strategies, underground structures, spinescence, and fruit morphologies, e.g., the evolution of samaroid fruits in Nissolia, shared with other genera in Dalbergieae, suggesting that they may be ancestral to the typical lomentaceous fruit characteristic of the other four genera. Studies of pollen morphology and floral ontogeny bring an important contribution to understand the evolution of the clade and will be discussed. Disk-shaped nectary was found in flowers of Adesmia and Nissolia, which have not been previously reported for the clade and may be a morphological character of taxonomic value.