Phylogenetics of Datureae (Solanaceae), including description of the new genus Trompettia and re–circumscription of the tribe

Abstract

AbstractDatureae is a tribe in the Solanaceae known for its charismatic large–flowered species (jimsonweeds and angel trumpets). The monophyly of the tribe is well established, but the recent finding that a species previously described in Iochroma (also Solanaceae) belongs in Datureae calls for a reassessment of the tribe's circumscription. Here we estimated the phylogeny of Datureae, including all of its 18 species, using three nuclear regions, and incorporated fossil information to estimate divergence times. Based on this phylogeny, we reconstructed the evolution of key aspects of reproductive morphology and life history to identify diagnostic features. Our molecular phylogenetic analyses suggest that the diversification of Datureae began roughly ca. 35 Ma, around the beginning of the Andean uplift. Within the tribe, Datura and Brugmansia are monophyletic sister taxa and the misplaced species of Iochroma is sister to the remaining species. Based on our morphological analysis, we describe the latter as a new monotypic genus Trompettia. Ancestral state reconstructions identify diagnostic features for each of the three genera and show a large suite of changes along the Datura branch, including the evolution of erect flowers, capsular fruit, and annual life history. Using these features, we formally re–circumscribe Datureae to include all genera and their species and provide a taxonomic key for the tribe.