Inclusion of the Cape genus Anisothrix in the Namibian-centred genus Pentatrichia (Asteraceae, Gnaphalieae) based on a molecular phylogenetic analysis

Abstract: A phylogenetic analysis of the small genus Pentatrichia, containing three species endemic to South Africa and Namibia, was undertaken using nuclear (ITS and 3′ ETS) and chloroplast (trnT–trnL) DNA sequence data. Generic circumscription was examined via the inclusion of appropriate outgroup taxa (Anisothrix and Athrixia). A fully-resolved phylogenetic hypothesis found all Pentatrichia species and subspecies to be reciprocally monophyletic based on three sampled specimens of each taxon. A well-supported sister relationship between the radiate P. rehmii subsp. avasmontana and non-radiate P. rehmii subsp. rehmii confirmed the results of a previous morphometric study. Pentatrichia was found to be non-monophyletic with the exclusion of Anisothrix kuntzei and A. integra, which were placed as a subclade within Pentatrichia, and sister to the type species P. petrosa. Morphological synapomorphies supporting the inclusion of Anisothrix with Pentatrichia are discussed, as well as the evolution of capitulum structure in the group. Anisothrix is synonymised with Pentatrichia and two new combinations were made. The expanded morphological concept of the genus Pentatrichia is presented with a key to all five species. [Copyright &y& Elsevier]