Phylogenetics of Bauhinia subgenus Phanera (Leguminosae: Caesalpinioideae) based on ITS sequences of nuclear ribosomal DNA

The pantropical legume genus Bauhinia is currently subdivided into four subgenera. Subgenus Phanera, with ca. 150 species, is the largest. A parsimony analysis was conducted on ITS sequence data from 38 species, with representatives from all four subgencra, and species sampled from nine of I I sections of subgen. Phanera, and including two Cercis species as the outgroup. The well-resolved strict consensus tree suggests that subgen. Phanera and the monotypic subgen. Barklya together form a monophyletic group. In the Phanera-Barklya clade, the African (sect. Tylosema), American (sect. Caulotretus), and Australasian (subgen. Barklya, subgen. Phanera sect. Lysiphyllum) species are the first (paraphyletic) lineages, while the Asian taxa (except species of sect. Lysiphyllum) form a monophyletic group. The ITS tree also revealed that sects. Phanera and Lasiobema are not monophyletic. Monophyletic groups supported by the phylogenetic analysis include ser. Fulvae and ser. Corymbosae of sect. Phanera, sect. Tubicalyx, and the Asian-Australasian sect. Lysiphyllum.