A taxonomic revision of the Cotula coronopifolia group (Asteraceae) and implications for the conservation statuses of the species

A taxonomic revision of the Cotula coronopifolia group is presented. We recognise seven species, largely restricted to wetland habitats within the Greater Cape Floristic Region of South Africa. The group is distinguished by prominent sheathing leaf bases and disciform heads. At the onset of this study, nine species had previously been recognised (two of which, Cotula bracteolata and C. pedunculata, are here reduced into synonymy), of which seven were regarded as species of conservation concern in previous IUCN Red List assessments. A key to the seven species is provided, together with an updated taxonomy which includes detailed morphological descriptions, typifications, diagnostic illustrations, and maps of known geographical distributions. As a result of the revised species concepts, improved identifications and detailed distribution data, the IUCN Red List categorisations were downgraded for three species (C. eckloniana, C. filifolia, C. vulgaris) and upgraded for one species (C. pusilla). This study highlights the importance of comprehensive taxonomic data to guide Red List assessments and other conservation efforts.