A molecular phylogeny of the pantropical papilionoid legume Aeschynomene supports reinstating the ecologically and morphologically coherent genus Ctenodon
Domingos Cardoso, Camila Mattos, Fabiana Ranzato Filardi, Alfonso Delgado‐Salinas, Matt Lavin, Pedro Luís Rodrigues de Moraes, Fernando Tapia-Pastrana, H. C. A. Lima
Abstract
The pantropical and morphologically diverse genus <i>Aeschynomene</i> (Leguminosae, Papilionoideae) comprises ca. 180 species, but its monophyly has never been comprehensively addressed in a molecular phylogenetic context of the dalbergioid clade. Here we have assembled the most complete DNA sequence data (nuclear ribosomal ITS/5.8S and the plastid genes <i>trnL</i> intron and protein-coding <i>matK</i>), representatively sampled both in <i>Aeschynomene</i> and the closely related <i>Dalbergia</i> and <i>Machaerium</i>, as well all currently accepted genera from the dalbergioids. The Bayesian and maximum likelihood phylogenetic analyses unequivocally confirm the non-monophyly of <i>Aeschynomene</i>. The pantropically distributed <i>Aeschynomene</i> sect. <i>Aeschynomene</i>, often inhabiting riparian and wetland habitats, is paraphyletic with respect to the mostly African genera <i>Bryaspis</i>, <i>Cyclocarpa</i>, <i>Geissaspis</i>, <i>Humularia</i>, <i>Kotschya</i>, and <i>Smithia</i>, as well as the South American monotypic genus <i>Soemmeringia</i>. The strongly supported and morphologically coherent clade comprising the American species traditionally classified within <i>Aeschynomene</i> sect. <i>Ochopodium</i>, with a greater ecological predilection for neotropical fire-prone savannas and the seasonally dry tropical forests and woodlands, is here elevated to generic rank. As such, this lineage is re-established as the previously monotypic genus <i>Ctenodon</i>. A complete description of <i>Ctenodon</i> and 78 new combinations for the American species and associated infraspecific taxa are provided, as well as 24 lectotypifications.