Infrageneric classification of Calibrachoa (Solanaceae) based on morphological and molecular evidence

The genus Calibrachoa (Solanaceae) comprises approximately 27 species that are found in open areas of southern South America, with the exception of C. parviflora, which also occurs in North America and Europe, probably as a result of introduction from South America and subsequent naturalization. The genus is closely related to Petunia, but differs in characteristics such as chromosome number, corolla aestivation, seed morphology, and leaf anatomy. Previous publications have shown that C. parviflora and C. pygmaea have morphological, ecological, and molecular features that differ from those of the other species of Calibrachoa, which had also been shown in a phylogenetic study using cpDNA RFLPs. In this paper, we present phylogenies based on chloroplast sequence data from psbB-psbH, trnS-trnG, and trnL-trnF intergenic spacers and the trnL intron, which corroborate the segregation of Calibrachoa species in two highly supported clades. On the basis of these results and the morphological and ecological evidence, we propose that each Calibrachoa clade be recognized at the subgeneric level. A new subgenus, Calibrachoa subg. Stimomphis, is recognized, which includes 25 species, whereas C. parviflora and C. pygmaea are in C. subg. Calibrachoa. A list of species that belong to each subgenus is provided, and lectotypes, neotypes, or epitypes are designated for eight names in Calibrachoa.