J. Stephen Boatwright

Earlier phylogenetic analyses of the family Thymelaeaceae using combined plastid ( matK , rbcL , rps16, trnL‐F ) and nuclear (ITS) regions showed that the African‐Malagasy genus Gnidia was extensively polyphyletic in relation to the southern African genera Lachnaea , Passerina and Struthiola , as well as to other Southern Hemisphere genera such as Drapetes , Kelleria and Pimelea . We present here a robust and well‐sampled phylogenetic analysis of the subfamily Thymelaeoideae, with sampling in Gnidia increased to 76% of the species, to better resolve the polyphyly of the genus . Our analysis retrieved seven lineages of Gnidia nested in four independent evolutionary clades within the “Gnidia group” of the subfamily Thymelaeoideae. We analysed the options available for re‐circumscribing Gnidia as a monophyletic genus, with secondary considerations of nomenclatural stability, phylogenetic and biogeographic information, and ease of identification. The option that we present retains the traditionally recognized genera Drapetes , Kelleria , Lachnaea , Passerina , Pimelea and Struthiola through the recognition of six lineages of Gnidia at the generic level. We propose that Gnidia be retained as a monotypic genus, including only the type of the genus name G. pinifolia . We reinstate the four previously recognized genera Basutica , Craspedostoma , Gnidiopsis and Thymelina and recognize the two new genera Epichroxantha and Phidia for the remaining two lineages of continental African Gnidia for which no names were available, plus the monotypic Zacharia for an anomalous Malagasy species that was previously excluded from Lasiosiphon. A taxonomic key and descriptions are provided for the genera in the “Gnidia group”. We also provide the necessary new combinations for names of Gnidia species now transferred to other genera.

Pteronia is a large genus of shrubs or woody perennials with more than 70 species. The genus is largely restricted to southern Africa, with one species in Zambia. The last taxonomic treatment of Pteronia was published in 1917 by J. Hutchinson and E. P. Phillips. In South Africa, where most of the species occur, the genus has been identified as one of the top priority genera for taxonomic research. Its taxa are poorly known in terms of their distribution and morphological variation within and among species. Morphological and anatomical studies revealed variation in characters such as leaf size, shape and vestiture, capitula shape, involucre shape, pappus series, cypselae shape, size and vestiture, presence or absence and type of trichomes, number of vascular bundles, type of secretory structure in the mesophyll, epidermal glands, epidermal cell shape in the leaves and cypselae (in transverse section) as well as the number of ribs and type of cells associated with vascular bundles at the ribs in the cypselae (in transverse section). A detailed taxonomic treatment is presented with descriptions, nomenclature, diagnostic characters, geographical distribution and maps, ecological information, as well as an updated key to the species. A total of 76 accepted and one imperfectly known species are recognised within the genus. Several species are treated as synonyms, and all names are typified, with justification presented for the choice of lectotypes.