New relatives of Oxalis pes-caprae (Oxalidaceae) from South Africa

The genus Oxalis in southern Africa contains more than 200 species, with the vast bulk of species in the Greater Cape Floristic Region (GCFR). Recent fieldwork has suggested that many await discovery. Here we investigate the identity of two apparently undescribed Oxalis species from Northern Cape, South Africa, using morphological comparisons with closely related taxa. We provide a preliminary phylogenetic placement using DNA sequence-based analyses of the Internal Transcribed Spacer (ITS) region. Both putative new species are distinguished from all known Oxalis species based on macro-morphological traits. Molecular data placed both within a clade consisting of the weedy O. pes-caprae and its close relatives. Oxalis hirsutibulba sp. nov. is characterised by densely hairy bulb tunics, a trait absent from all known members of the O. pes-caprae clade. Oxalis fenestrata sp. nov. is unique in producing apple green succulent stems and leaflets usually with translucent white markings at their incisions. We also provide the first phylogenetic placement of the GCFR narrow endemic O. lasiorrhiza in the O. pes-caprae clade. In conjunction with several other recent discoveries, these two new species and the phylogenetic placement of O. lasiorrhiza show that the O. pes-caprae clade is much more speciose than previously estimated.