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• Four species new to science are described. • Detailed photographic plates and distribution maps are included. • Conservation assessments are provided for all four species. Four new Indigofera species are described from the Greater Cape Floristic Region (GCFR). Indigofera barkeri is a new annual from the Richtersveld, with small flowers, 3.5–4.0 mm long, pinnately trifoliolate leaves and laterally flattened seeds. Indigofera dodii is endemic to the area around Cape Town, growing on granite and shaly slopes. It has apically congested racemes, flowers 6.0–6.5 mm long, digitately trifoliolate leaves, fruit with a hispid indumentum and tuberculate seed testas. Indigofera gariepensis , endemic to dry riverbeds in the eastern Richtersveld, is recognized by its alternate, silky-velutinous leaflets and calyx lobes ± equal in length to its 5.5–6.5 mm long magenta flowers. Indigofera tanquana is known from only two collections and is endemic to the western Tanqua Karoo. It is easily recognized by its broad old grey stems, spinescent branches, simple grey-canescent leaves that aggregate on woody brachyblasts and reddish-magenta flowers. Detailed morphological descriptions are presented with composite photographic plates for each species. Notes on ecology, detailed diagnoses comparing with closely related species, a distribution map and an IUCN red list conservation assessment for each species is also provided. [ABSTRACT FROM AUTHOR]

Premise: Southern Africa is a biodiversity hotspot rich in endemic plants and lichen-forming fungi. However, species-level data about lichen photobionts in this region are minimal. We focused on Trebouxia (Chlorophyta), the most common lichen photobiont, to understand how southern African species fit into the global biodiversity of this genus and are distributed across biomes and mycobiont partners., Methods: We sequenced Trebouxia nuclear ribosomal ITS and rbcL of 139 lichen thalli from diverse biomes in South Africa and Namibia. Global Trebouxia phylogenies incorporating these new data were inferred with a maximum likelihood approach. Trebouxia biodiversity, biogeography, and mycobiont-photobiont associations were assessed in phylogenetic and ecological network frameworks., Results: An estimated 43 putative Trebouxia species were found across the region, including seven potentially endemic species. Only five clades represent formally described species: T. arboricola s.l. (A13), T. cf. cretacea (A01), T. incrustata (A06), T. lynniae (A39), and T. maresiae (A46). Potential endemic species were not significantly associated with the Greater Cape Floristic Region or desert. Trebouxia species occurred frequently across multiple biomes. Annual precipitation, but not precipitation seasonality, was significant in explaining variation in Trebouxia communities. Consistent with other studies of lichen photobionts, the Trebouxia-mycobiont network had an anti-nested structure., Conclusions: Depending on the metric used, ca. 20-30% of global Trebouxia biodiversity occurs in southern Africa, including many species yet to be described. With a classification scheme for Trebouxia now well established, tree-based approaches are preferable over "barcode gap" methods for delimiting new species., (© 2024 Botanical Society of America.)