Taxonomy of the four-scaled species of Struthiola L. (Thymelaeaceae)

Abstract We present a taxonomic treatment of the four-scaled species of Struthiola (Thymelaeaceae) in which we recognise two species, S. striata and S. tetralepis , differing in ecology, growth form and flower morphology (bracteole and hypanthium length as well as the shape and colour of the sepals). Both species have amphistomatic foliage, with a higher density of stomata on the adaxial surface of the leaves. The two species are endemic to the Core Cape Floristic Region of South Africa but have allopatric distributions, S striata occurs on coastal sandy flats and lower slopes in Sand Fynbos, whereas S. tetralepis is restricted to upper mountain slopes in Cape Wineland Shale Fynbos. Six lectotypes are designated and the previously data deficient (DDD) S. tetralepis var. glabricaulis Schltr. is reduced into synonymy.