Epischoenus, C. B. Clarke

Elliott, T. L. & Muasya, A. M., 2017, Taxonomic realignment in the southern African Tetraria (Cyperaceae, tribe Schoeneae; Schoenus clade) *, South African Journal of Botany 112, pp. 354-360 : 358

6.3. Epischoenus and allies

Epischoenus C.B.Clarke ( Fig. 2C, H ) is a small genus of eight species endemic to the CFR that is also part of the Schoeneae tribe ( Goetghebeur, 1998; Manning and Goldblatt, 2012; Viljoen et al., 2013). Apart from M.R. Levyns ( Leighton et al., 1947; Levyns, 1959), little taxonomic attention has been given to Epischoenus since the formation of the genus by C.B.Clarke. Browning and Gordon-Gray (1995) compared the spikelet morphology of Epischoenus to Schoenus and made the assertion that the two genera should be treated as one, instead of Epischoenus having separate endemic African status. In addition, they noted that the current species delimitation in Epischoenus is not acceptable and the entire genus should be revised. Phylogenetic data ( Viljoen et al. 2013) confirm Epischoenus to be close to Schoenus and embedded in Tetraria ( Fig. 1 ). Based on preliminary examination of herbarium specimens, we concur that a revision of all Epischoenus species is required, as the current available keys do not allow unambiguous identification of taxa (see Levyns, 1959), and there is a large amount of variation in the different morphotypes included within several of the species. We anticipate that there are between three and seven new species within the clade currently named Epischoenus .

Figures

Fig. 2. Examples of plants from each of the four clades of Schoenus found in southern Africa, showing the corresponding spikelets beneath each plant: A and F—S. nigricans, B and G—T.compar, C and H—Epischoenus sp. and D and I—T.cuspidata.A ‘reticulate-sheathed’ Tetraria of the Tricostularia clade is shown in E, with its spikelet shown in J.The black scale bar beneath the spikelets in F–J represents 1 mm.

Fig. 1. Maximum likelihood phylogenetic reconstruction of the Schoeneae clade of sedges based on ETS,ITS,rbcL,rps16 and trnL-trnF (adapted from Viljoen et al., 2013). The seven major clades of Schoeneae and their approximate divergence times in millions of years are shown in A,with the southern African species highlighted in light grey. Phylogenetic relationships within the Schoenus clade are shown in B, which illustrates the four clades found in southern Africa: S. nigricans, T.compar–T. picta, Epischoenus and T.cuspidata and allies.