Phylogeny of Cobaea (Polemoniaceae) based on sequence data from the ITS region of nuclear ribosomal DNA

The phylogenetic relationships of 16 of the 18 species of the neotropical genus Cobaea (Polemoniaceae) were investigated using sequences of the ITS1 and ITS2 regions of nuclear ribosomal DNA. Cantua and Bonplandia were used as outgroups. Six most-parsimonious trees (length = 558 steps, CI excluding uninformative characters = 0.688, RI = 0.875) were produced, and support for most branches, based on bootstrap and decay analyses, was quite strong. Insertion/deletion events provide further support for some clades. There are two unresolved nodes in the strict consensus tree, and one of the unresolved nodes is among samples of one species. The ITS phylogeny suggests that two of the three sections of Cobaea are not monophyletic; the third is monotypic. The three characters used to distinguish the sections, corolla lobe shape, inflorescence position, and stamen length, were of questionable utility in sectional circumscription.