A phylogenetic analysis of Dicoma cass. and related genera (Asteraceae : Cichorioideae : Mutisieae) based on morphological and anatomic characters

This study reports a phylogenetic analysis of the genus Dicoma and the rela ted genera Achyrothalamus, Erythrocephalum, Pasaccardoa, and Pleiotaxis (Mu tisieae, Asteraceae), which share a series of morphological characters of t he corolla, ray floret epidermis, anther appendages, and style branches. A matrix of 77 morphological and anatomical characters was used for the analy sis. The genera Gochnatia and Oldenburgia were used as outgroups. The topol ogy of the resulting consensus cladogram suggests that the genus Dicoma app ears paraphyletic. A clade including Dicoma and Pasaccardoa appears monophy letic with subgroups clearly defined by a large number of synapomorphies. T hese findings indicate that maintenance of Pasaccardoa as an independent ge nus implies a need to divide Dicoma into several genera. The genera Pleiota xis, Achyrothalamus, and Erythrocephalum form a monophyletic group. Issues relating to the geographical origin of Dicoma (probably Madagascar or south ern Africa), and to the evolution of the different species groups, are brie fly discussed.