Bangiales (Rhodophyta) in New Zealand: current state of knowledge and future directions

Members of the red algal order Bangiales are morphologically simple, with the gametophyte generation consisting of either filaments or blades, and the sporophyte generation consisting of microscopic uniseriate branched filaments. An ancient lineage, the order is distributed worldwide. The foliose species are the basis for the most valued seaweed aquaculture crop globally. In New Zealand, foliose species are known as karengo (parengo), and are highly prized by Māori. Phylogenetic analyses presented here highlight the great diversity of both species and genera in New Zealand with at least 47 species present in five filamentous genera (three undescribed, and two endemic and monotypic – <i>Dione</i> and <i>Minerva</i>), and four foliose genera (<i>Clymene, Porphyra</i>, <i>Pyropia,</i> and <i>Lysithea</i>). Based on the data available to date, it is likely that there are more undiscovered species. The diversity of New Zealand taxa is spread throughout the evolutionary lineages of the Bangiales. It is likely that members of this order have been on New Zealand shores prior to the breakup of Gondwana. Our analyses point to strong affinities of the New Zealand foliose species with other southern hemisphere regions. While international research on life history and reproductive modes in members of the Bangiales has revealed an extraordinary range of asexual, sexual and vegetative reproductive modes in both gametophyte and sporophyte stages, life history complexity and the genetic and ecological consequences have not been investigated for New Zealand species. While foliose Bangiales have special status in New Zealand as taonga species, little is understood about their vulnerability to human-mediated environmental changes, how changing climate may influence phenology of reproduction, and whether there are differential impacts on survival of gametophytes and sporophytes. Greater understanding of the biology, ecology and reproduction of Bangiales is critical for future resource management and conservation of genetic diversity.