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A taxonomic revision of Schoenus cuspidatus and allies (Cyperaceae, tribe Schoeneae)—Part 1

Elliott, T.L., Barrett, R.L., Muasya, A.M.
South African journal of botany 2019 v.121 pp. 519-535
Cyperaceae, culms, fruits, graminoids, herbaria, leaves, new species, spikelets, taxonomic keys, taxonomic revisions, South Africa
The first of a two-part taxonomic revision of the morphologically complex Schoenus cuspidatus and allies group is presented. This revision builds on two recent taxonomic works of which the first transferred 24 southern African species from Tetraria and Epischoenus into Schoenus, and the second revised the taxonomy of the Schoenus compar – Schoenus pictus and allies group, as well as described three new species from South Africa. Here, we use data from recent field collections and a review of specimens from 12 herbaria to revise the delimitations and distributions of three species (Schoenus bolusii, Schoenus exilis and Schoenus graminifolius). In addition, we describe seven new species: six of which are endemic to the Cape Floristic Region (Schoenus calceolus, Schoenus crassiculmis, Schoenus submarginalis, Schoenus prophyllus, Schoenus purpurascens and Schoenus quartziticus), while the seventh is endemic to the Eastern Cape and KwaZulu Natal Provinces of South Africa (Schoenus limosus). We also resolve nomenclatural and species delimitation issues in Schoenus auritus and Schoenus ligulatus, with Schoenus autumnalis and Schoenus variabilis being subsumed in an enlarged circumscription of Schoenus ligulatus. Species in the Schoenus cuspidatus group are caespitose, perennial graminoids, with scapose and terete culms. However, there are differences in sheath and ligule type, which can be either firm or membranaceous, as well as leaf type, which vary from channelled and terete to non-channelled and flat. Importantly, differences in spikelet and nutlet shape distinguish many of the species in this group. A taxonomic key is presented, the nomenclature is updated, and detailed descriptions and distribution maps are provided for these 12 Schoenus species.