Taxonomic notes on the Acanthopsis disperma-hoffmannseggiana complex (Acanthaceae, tribe Acantheae), with an interim key to members of the genus

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 disperma-hoffmannseggiana 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.

Taxonomic notes on Acanthopsis (Acanthaceae, tribe Acantheae): the group with semi-dense spikes and 5-fid bracts

“…For the description of the bracts we follow the same terminology as in Steyn & Van Wyk (2015, 2016. Except were stated otherwise, the middle to upper bracts within an inflorescence were used in the key and descriptions.…”

“…Acanthopsis Harvey (1842: 28) is a morphologically distinct but taxonomically poorly understood genus confined to South Africa and Namibia (Steyn & Van Wyk 2015). It can easily be distinguished from the closely related Blepharis Jussieu (1789: 103) by the unlobed style (not bilobed) and the stamen filaments without an appendage (with a forwarddirected appendage on the posterior pair of stamen filaments) (Vollesen 2000).…”

“…habit , Steyn & Van Wyk 2016, bract morphology (Nees von Esenbeck 1847, , Steyn & Van Wyk 2015, 2016 and indumentum of the leaves and floral bracts (Meyer 1961, Steyn & Van Wyk 2015, 2016. Up to now inflorescence density was mentioned as part of the genus description, e.g.…”

“…The density of the inflorescences was found to be a taxonomically important character by Steyn & Van Wyk (2015) to distinguish two artificial groups, namely a "Dense spike" and "Open-spike group" (Steyn & Van Wyk 2015: 7). Since 2015, the definitions of a dense vs. open (now called "semi-dense") spike have been refined, and an amended key to the groups within Acanthopsis is provided (see "Taxonomic treatment" below).…”

A synopsis of Rhinacanthus (Acanthaceae) in Angola and Namibia

“…and Barleria L. Recent studies in Acanthopsis Harv. (Steyn & van Wyk 2015, Barleria L. (Darbyshire et al 2012 & in prep. ;Nyirenda 2012), Hypoestes R. Br.…”