Abstract:
Acanthopsis is a taxonomically poorly understood genus confined to arid parts of southern Africa. This
contribution is the first detailed assessment of the diversity within the Acanthopsis dispermahoffmannseggiana
complex, the latter of which comprises the bulk of the specimens of the genus
represented in herbaria. Species concepts are resolved and the misapplication of names is noted. In
addition to the recognition of A. disperma and A. hoffmannseggiana, five new species of Acanthopsis
formerly treated under these two names, are described, namely A. tuba and A. ludoviciana (both confined
to the Richtersveld, Northern Cape, South Africa), A. adamanticola (endemic to southern Namibia), A.
villosa (endemic to Bushmanland, Northern Cape) and A. dispermoides (endemic to the Western Cape,
South Africa). The names A. disperma and A. hoffmannseggiana are lectotypified here. An identification
key to the members of the Acanthopsis disperma-hoffmannseggiana complex is provided, as well as an
interim key to the major artificial groupings in the genus, the taxonomy of some which still needs to be
resolved.
