Two new species of Arctotis (Asteraceae: Arctotideae) from the Namaqualand Sandveld Bioregion, South Africa and reappraisal of the identity of Arctotis melanocycla

A taxonomic revision of Arctotis L. is in progress. In this study two putative unnamed taxa from the Namaqualand Sandveld Bioregion of northwestern South Africa were assessed to be morphologically distinct based on examination of herbarium specimens, fresh collections and field observations. The newly recognised species are described as Arctotis anneliseae R.J.McKenzie and Arctotis canaliculata R.J.McKenzie. Arctotis anneliseae is distinguished from A. decurrens Jacq. by its semi-succulent stems, fleshy obovate-spathulate or lyrate-pinnatifid leaves clothed with dense, appressed, lanate indumentum, non-fimbriate receptacle, obtuse pappus scales, and outer involucral bracts with a shorter, reflexed apical appendage clothed in appressed indumentum. This species is currently known from two restricted areas of the southern Namaqualand coast and is gravely threatened by mining of heavy mineral-rich sediments and livestock grazing. A conservation threat assessment of Endangered is recommended based on the IUCN Red List Categories and Criteria. Arctotis canaliculata is a clump-forming suffrutex with linear, lanceolate-obovate or pinnatifid, canaliculate, semi-succulent leaves clothed with dense appressed indumentum, rounded pappus scales, and outer involucral bracts that lack an apical appendage. Arctotis canaliculata is distributed on the arid northwestern coastal plain between the Gariep and Swartlintjies rivers. The name Arctotis melanocycla Willd. is lectotypified and is placed in the synonymy of A. decurrens.