Evolution of a Charismatic Neotropical Clade: Molecular Phylogeny of Tabebuia s. l., Crescentieae, and Allied Genera (Bignoniaceae)

Tabebuia is one of the most commonly encountered genera of Bignoniaceae in the neotropics. Previous research has suggested that this genus may be paraphyletic and contain the tribe Crescentieae. Molecular sequence data of the chloroplast trnL-F and ndhF regions were used to reconstruct the phylogeny of Tabebuia, Crescentieae and related genera. A previously unrecognized clade of Neotropical, arboreal Bignoniaceae characterized by palmately compound leaves was identified and is referred to as the Tabebuia alliance. Within this group, Tabebuia is confirmed to be paraphyletic, since it includes Crescentieae, Spirotecoma, and Ekmanianthe. The position of Zeyheria, Godmania, and Cybistax with relation to Tabebuia is equivocal. Sparattosperma is sister to the rest of the Tabebuia alliance. Spirotecoma is inferred to be sister to Crescentieae. The phylogeny of Tabebuia presented here corresponds to the species groups established by Gentry, while at the same time highlighting the need for taxonomic revisions. When considered on a biogeographic scale, the phylogeny indicates a minimum of four dispersal events from the mainland to the Greater Antilles.