Reinstatement of Sabdariffa and new combinations to support a monophyletic concept of Hibiscus (Malvaceae: Hibisceae)

Recent phylogenetic studies have demonstrated that Hibiscus L. as traditionally defined is grossly polyphyletic. In a major step towards making Hibiscus monophyletic, the genus Sabdariffa (DC.) Kostel. is here reinstated for Hibiscus section Furcaria DC. In total, 123 new combinations are provided (for 117 species and 6 subspecies). Numerous lectotypes are designated. Sabdariffa has a pantropical distribution, with high species diversity in tropical Africa, tropical America and northern Australia. False roselle (Sabdariffa acetosella (Welw. ex Hiern) M.M.Hanes & R.L.Barrett), kenaf (Sabdariffa cannabina (L.) M.M.Hanes & R.L.Barrett) and roselle (Sabdariffa gossypiifolia (Mill.) M.M.Hanes & R.L.Barrett) are all of global economic significance. Ma‘o hau hele (Sabdariffa brackenridgei (A.Gray) M.M.Hanes & R.L.Barrett) is the official state flower of Hawai’i. Full synonymy and type details are included, along with distributions and references to existing descriptions for all species. A series of regional keys to species is presented here with current names in Sabdariffa.