Dyschoriste Nees (Acanthaceae: Ruellieae) — Clarification of species previously recognised in Chaetacanthus Nees and two threatened new species from South Africa

• The circumscription of four species is clarified. • A new name ( Dyschoriste glandulifera ) is provided for Chaetacanthus glandulosa. • A threat status of Critically Endangered is recommended for two species. Chaetacanthus was described to accommodate species of Dyschoriste that had two stamens and two staminodes rather than four stamens. Four species had names in Chaetacanthus , but those names have been widely misapplied and very many herbarium specimens and iNaturalist observations have been wrongly identified. The identity and circumscription of the previously named taxa are clarified to lay a foundation on which a revision of species previously regarded as Chaetacanthus can be based. Habit, leaf size and shape, corolla morphology and types and distribution of hairs are important characters for recognising species in the group. Two of the several undescribed species are described to facilitate their protection, as a threat status of Critically Endangered is recommended for both.