A morphometric analysis of the Bonatea speciosa complex (Orchidaceae) and its implications for species boundaries

Species boundaries in rapidly evolving lineages are often blurred, necessitating analysis of the full range of variation within a complex in order to identify traits that can be used to diagnose taxa. The delimitation of Bonatea speciosa (L. f.) Willd. has been controversial, as most, but not all, recent authors have included within the concept of this species several additional taxa that were formerly recognised at the species level, including Bonatea boltonii (Harv.) Bolus and Bonatea antennifera Rolfe. Morphological variation across the Bonatea speciosa complex (Orchidaceae) was explored using principal component and cluster analysis. Scatter plots were used to identify characters that could potentially be used to diagnose taxa. These data support the recognition of three distinct species, B. speciosa, B. antennifera and B. boltonii, instead of a single entity. A taxonomic account of southern African taxa within the B. speciosa complex is presented.