Marasmodes (Asteraceae, Anthemideae), the most threatened plant genus of the Cape Floristic Region, South Africa

We confirm Marasmodes to be the Cape Floristic Region and South Africa's most threatened plant genus, classifying ten, of the thirteen species recognised here, as Critically Endangered (of which one, M. reflexa, is possibly extinct), and the remaining three as Endangered. The species are all highly localised to specialised, transitional habitats along moisture gradients or across soil-type boundaries. All are restricted to lowland vegetation of which more than 80% have already been lost, predominantly to agriculture and urban expansion. The remaining fragments are threatened further by significant development pressure. Historically, the conservation of Marasmodes has been impeded by a lack of collections and taxonomic confusion. We present here a revision of this highly threatened genus, in which we describe two new species, Marasmodes crewiana Magee & I.Ebrahim and Marasmodes oppositifolia Magee & Koopman. We also reduce two species, M. beyersiana S.Ortiz and M. schlechteri Magee and J.C.Manning, into synonymy (with M. polycephala DC and M. oubinae S.Ortiz, respectively).

We therefore also review the conservation status of all the species in light of the revised taxonomic concepts and new distribution and population data. Urgent interventions, particularly habitat restoration and ex-situ cultivation of plants for reintroduction to the wild, are needed to prevent the imminent extinction of most of the species.