Phylogenetic analysis of nuclear ribosomal ITS/5.8S sequences in the tribe Millettieae (Fabaceae): Poecilanthe-Cyclolobium, the core Millettieae, and the Callerya group

The taxonomic composition of three principal and distantly related groups of the former tribe Millettieae, which were first identified from nuclear phytochrome and chloroplast trnK/matK sequences, was more extensively investigated with a phylogenetic analysis of nuclear ribosomal DNA ITS/5.8S sequences. The first of these groups includes the neotropical genera Poecilanthe and Cyclolobium, which are resolved as basal lineages in a clade that otherwise includes the neotropical genera Brongniartia and Harpalyce and the Australian Templetonia and Hovea. The second group includes the large millettioid genera, Millettia, Lonchocarpus, Derris, and Tephrosia, which are referred to as the "core Millettieae" group. Phylogenetic analysis of nuclear ribosomal DNA ITS/5.8S sequences reveals that Millettia is polyphyletic, and that subclades of the core Millettieae group, such as the New World Lonchocarpus or the pantropical Tephrosia and segregate genera (e.g., Chadsia and Mundulea), each form well supported monophyletic subgroups. The third lineage includes the genera Afgekia, Callerya, and Wisteria. These genera are resolved as a basal subclade in the inverted-repeat-lacking clade, which is a large legume group that includes the many well known temperate and herbaceous legumes, such as Astragalus, Medicago and Pisum, but not any other Millettieae.