Revisiting ‘A monograph on the Polychaeta of southern Africa’: establishing taxonomic research priorities in southern Africa

Originally published in 1967, John H Day’s work ‘A monograph on the Polychaeta of southern Africa’ is still used widely to identify polychaetes. However, ongoing taxonomic revisions have revealed that several putative cosmopolitan or locally widespread taxa contained in the monograph are complexes of species with discrete distributions, globally and locally. This study therefore aimed to develop lists of taxa, including unresolved cosmopolitan and widespread indigenous species, that should be prioritised for revision to unlock their hidden diversity. A total of 609 species (56 families and 316 genera) were scored according to their time since description, global and local distribution, availability of genetic data and vouchers, alien status and economic importance, and then ranked. At least half the taxa reported locally are unresolved cosmopolitan complexes, and a quarter have wide local distributions, probably hiding cryptic diversity. Accordingly, we estimate that approximately 500 polychaete species are still undescribed in southern Africa. The four highest-scoring families (Syllidae, Nereididae, Spionidae and Eunicidae) comprise 25% of the species and 53–85% of the unresolved cosmopolitans, while multiple species are considered pests, used as bait or possible aliens. Prioritised genera (e.g. Eunice, Syllis, Nereis, Prionospio, Dipolydora) and species (e.g. Pseudonereis variegata) are usually members of prioritised families, but some species are not (e.g. Sabella cf. pavonina, Fimbriosthenelais zetlandica, Paleanotus chrysolepis, Gunnarea gaimardi, Capitella capitata). All taxon levels should therefore be considered to ensure that all species most in need of revision are identified. Ways to facilitate revisions are discussed.