Refined generic and infrageneric classification of the Cape Psoraleeae clade (Fabaceae) – taxonomic studies in the phylogenomic era

• Psoraleeae’s evolutionary history and species diversity is found in the Cape. • Otholobium has been recently lumped into Psoralea due to non-monophyly. • We use phylogenomic data to infer generic relationships and to revise taxonomy. • Four clades are strongly supported, three of which are recognized at generic level. • Genus Otholobium is restored, with anomalous (two) species placed into Afrolobium . • We present identification key and make nomenclature changes to reflect current knowledge. The Cape Psoraleeae is a classic Cape clade, characterized by a recent diversification, and occurring in diverse habitats in the Greater Cape Floristic Region. Intensive taxonomic and phylogenetic studies over the past 20 years have contributed to the description of 48 species new to science, growing the genus to nearly 130 species, and changing generic classification. But there have been doubts on the taxonomic validity of two genera, Hallia and Otholobium , which had been previously recognized at genus level, but were synonymized under Psoralea following Sanger-based phylogenetic analyses. We use phylogenomic data, sampling over 70 % of species in the Cape Psoraleeae, to i) evaluate the monophyly of Psoralea , and ii) identify strongly supported clades that can be recognized at either the infrageneric or generic level. There is strong support for the backbone topology, which is resolved into three clades (core Psoralea incorporating Hallia pro parte , core Otholobium , and a clade containing the anomalous O. swartbergense and O. sericeum ). We here refine the generic classification to recognize the O. swartbergense / O. sericeum clade as a new genus Afrolobium , providing nomenclatural changes for the species; resuscitating Otholobium; and maintaining Hallia within Psoralea as a new subgenus. The taxonomic changes made here take the new phylogenetic framework into consideration, ensure monophyly of genera and subgenera, and aspire to provide classification that is predictable and practical to apply by end users. We further discuss trends in species discovery by discussing the placement of new species on the phylogenetic tree; most newly discovered species belong to the two largest clades and occur within the Greater Cape Floristic Region.