A treatment of the African genus Schistostephium (Compositae: Anthemideae)
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ISSN: 0075-5974 (PRINT) ISSN: 1874-933X (ELECTRONIC)
A treatment of the African genus Schistostephium (Compositae: Anthemideae) T. Harris1 Summary. The African genus Schistostephium Less. (Compositae: Anthemideae) is revised; eight species are recognised. A key to the species is provided, together with descriptions and illustrations. Conservation assessments have been carried out for each species. Six names are lectotypified: Tanacetum crataegifolium DC., Schistostephium saxicola Hutch. and Schistostephium villosum Hutch. (here all regarded as synonyms of Schistostephium crataegifolium (DC.) Fenzl ex Harv.), Schistostephium dactyliferum Hutch. (treated here as a synonym of Schistostephium heptalobum Oliv. & Hiern), Tanacetum argyraeum DC. (treated here as a synonym of Schistostephium flabelliforme Less.) and Schistostephium oxylobum S. Moore. Key Words. Asteraceae, Peyrousea, Tanacetum.
Introduction Schistostephium Less. is a genus in the Compositae, subfamily Asteroideae (Funk et al. 2005), tribe Anthemideae Cass., subtribe Cotulinae Kitt. The Anthemideae is largely African, although some genera are Eurasian, North American and a few are more widespread. Most genera within the subtribe Cotulinae are restricted to Africa but genera such as Leptinella Cass. and Cotula L. are distributed across Australasia and South America. Several genera in Anthemideae are widely cultivated and some have become naturalised, e.g. two species of Anthemis L. have become naturalised in North America while three species of Eriocephalus L. and four species of Ursinia Gaertn. have become naturalised in Australia. Other widely cultivated genera from tribe Anthemideae include Chrysanthemum L. (the florists’ chrysanthemum), Leucanthemum Mill. (ox-eye daisy) and Anacyclus L. The circumscription of Schistostephium is uncontroversial and the treatment outlined here includes Peyrousea DC. as indicated by Bremer & Humphries (1993). Schistostephium is restricted to Central and Southern Africa, as far north as the Democratic Republic of Congo, but has not been recorded from Angola, Namibia or Botswana. Five of the eight species recognised here have restricted distributions within South Africa and Swaziland. The eight species recognised are herbs or shrubs and many of the distinguishing characters are vegetative. Floral organs vary very little within the genus; all species have yellow corollas with four equally sized lobes with no significant variation in style, stamens or achene. However, the number of florets found in the capitulum and the size and shape of the capitulum are useful for delimiting species.
The group of genera containing Cotula, Hilliardia B. Nord., Hippia L., Leptinella, Soliva Ruiz & Pav., Thaminophyllum Harv. and Schistostephium has been shown to be a strongly supported monophyletic group in Himmelreich et al. (2008). In Oberprieler et al. (2007) this strongly supported monophyletic group of genera is referred to as subtribe Cotulinae Kitt. Despite this evidence of Schistostephium belonging to a well-supported monophyletic subtribe
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