Marine benthic invertebrate biodiversity in South Africa: Advances and gaps in taxonomic and genetic knowledge.

Traditional taxonomy is the foundation of biodiversity science with modern molecular techniques and integrated approaches now essential for advancing our understanding of ocean life. Without improved knowledge of marine biodiversity, it is impossible to address the biodiversity crisis or develop the fundamental science needed to assess, plan and manage marine biodiversity and maintain its many benefits. South Africa harbours exceptional marine biodiversity and has ongoing efforts to systematically list, map, monitor, assess and conserve this national asset. This review consolidates progress in taxonomic knowledge, species lists and molecular barcoding and identifies gaps for benthos-associated invertebrates, a group receiving the least taxonomic attention in the country. Building on previous efforts that revealed major capacity and knowledge gaps, this review updates the state of knowledge, providing a new and accessible baseline and evaluates progress over the past 27 years to guide the next phase of marine invertebrate biodiversity research. Taxonomic advances across 11 major phyla are presented, nine of which have received some level of dedicated revision at phylum, class or family level. Although the taxonomic crisis persists and progress is variable across groups, there has been an appreciable increase in species discovery over the last two decades with more than a thousand invertebrate species added to national lists. Key challenges that hamper efforts and enabling factors supporting progress are identified, with recommendations to consolidate and increase knowledge and capacity, accelerate marine biodiversity discovery and mapping, and address key gaps in our understanding of South Africa's marine invertebrate fauna.