| A revision of the neotropical genus Cobaea (Polemoniaceae) was undertaken using traditional morphology, pollen morphology, fieldwork, and biogeography, and a phylogeny was estimated based on sequence data from the ITS regions of nuclear ribosomal DNA. A taxonomic treatment is rendered in which 18 species are recognized. A new sectional arrangement is proposed, three new species are described and illustrated, and keys to the species are provided. The phylogeny was used to examine the evolution of floral morphology within the genus.;Within the family, Cobaea is well-defined by a number of unique characters including a climbing habit; pinnately compound leaves with the terminal leaflet modified as a tendril; large, campanulate flowers; nearly free sepals; septicidally dehiscent capsules; and very large, pantoporate, reticulate pollen. The 18 species of Cobaea are distributed from Peru to northern Mexico and typically occur in montane cloud forests. Because of its rarity and tropical distribution, it was previously the least studied genus in this otherwise well-known family.;Traditionally the genus has been divided into three sections, sect. Aschersoniophila, sect. Cobaea, and sect. Rosenbergia. Based on the results of the DNA analysis, sect. Aschersoniophila was reduced to synonymy within sect. Rosenbergia; some species of sect. Cobaea were transferred to sect. Rosenbergia; and two new monotypic sections were erected, sect. Pachysepala and sect. Triovulata. Section Cobaea is mainly Mexican, with one species occurring in the Andes, sect. Pachysepala is restricted to Mexico and Guatemala, sect. Rosenbergia is widespread in the neotropics, and sect. Triovulata is restricted to Mexico, Costa Rica, and Panama.;The remarkable diversity of floral morphology among the species of Cobaea is most apparent among sections of Cobaea as well as within sect. Rosenbergia. The species of sect. Cobaea are all very similar in terms of floral morphology. Within sect. Rosenbergia some characters, such as anther position and corolla lobe shape, are homoplastic and the data suggest that the pattern of distribution of character states for these and other characters results from evolutionary parallelisms and reversals among the lineages. |
