A synoptic review and new infrageneric classification for the genus Haworthiopsis (Xanthorrhoeaceae: Asphodeloideae)

Abstract

Haworthiopsis was established in 2013 to accommodate the species formerly classified under the subgenus Hexangulares of the genus Haworthia. This new genus is near-endemic to South Africa and found in most of the provinces of the country. It is also known from southern Namibia, Swaziland and possibly Mozambique. A total of 18 species are currently recognised in Haworthiopsis. However, this circumscription renders the genus paraphyletic with H. koelmaniorum sister to a polytomy comprising the rest of the Haworthiopsis taxa and Gasteria. In this contribution, seven new combinations are published (H. fasciata var. browniana, H. reinwardtii var. reinwardtii f. chalumnensis, H. reinwardtii var. reinwardtii f. kaffirdriftensis, H. reinwardtii var. reinwardtii f. olivacea, H. tessellata var. crausii, H. viscosa, H. scabra var. smitii) and two changes of status (H. koelmaniorum var. mcmurtryi, H. viscosa var. variabilis). An amplified description of the genus is provided. Six sections formerly recognised under Haworthia (subg. Hexangulares) are applied and adapted to Haworthiopsis, with some amendments. A new section, H. sect. Koelmaniorum, is described here. New combinations for hybrid taxa in Haworthiopsis that were previously described as species of Haworthia are given.