Abstract
Bostrychia is a widespread genus and has recently received considerable molecular attention, leading to insights into its evolution, and nomenclatural changes. We investigated the species of Bostrychia in New Zealand, to produce an identification key and highlight the nomenclatural changes of these species. We incorporated into a molecular phylogeny two species prominent in New Zealand ( B. gracilis, B. vaga ) that have not be investigated phylogenetically before. Our results show thatthree species of Bostrychia ( B. arbuscula, B. gracilis, B. vaga ), mainly restricted to New Zealand, share a common ancestor. Only B. vaga is known outside New Zealand. This restricted distribution is unusual for species within this genus in which many are widespread. A phylogeographic study of another New Zealand and Southern Hemisphere species, B. intricata , indicates that this species consists of several lineages that are found locally. These lineages, and physiological difference between lineages, suggest that cryptic species may be found within this species, as is common in many other red algal species. Our data highlight the unique nature of the New Zealand flora within this common genus and suggest continued investigation is warranted.