RELATIONSHIPS AMONG GENERA OF THE INFORMAL DICHROSTACHYS AND LEUCAENA GROUPS (MIMOSOIDEAE) INFERRED FROM NUCLEAR RIBOSOMAL ITS SEQUENCES

Abstract Previous attempts to elucidate sister group relationships among the genera of the informal Dichrostachys and Leucaena groups of the tribe Mimoseae have been hampered by incomplete taxon sampling, incomplete knowledge and poor circumscription of a number of the constituent genera, primary reliance on a limited set of morphological characters, and uncertainty about sister group relationships across the Mimoseae as a whole. Here we present a densely sampled informal Dichrostachys and Leucaena group analysis that includes all the constituent genera and 72 of the 91 species using a new DNA sequence data set from the nrDNA 5.8S and flanking internal transcribed spacer regions (ITS1 and ITS2). This analysis confirms the previously proposed realignment of the informal Leucaena group to include Leucaena, Desmanthus, Schleinitzia and Kanaloa, and the Dichrostachys group to include Dichrostachys, Gagnebina, Alantsilodendron and Calliandropsis, as well as the exclusion of Neptunia from these groups. The analysis also provides the first species-level molecular phylogeny for the genera of the Dichrostachys group, and species relationships within this group are discussed in relation to morphology and generic delimitation. The pattern of ITS variation within Desmanthus indicates incomplete sampling of ITS diversity limiting the usefulness of the current ITS gene tree to infer species relationships within the genus