Systematic review of Neanthes Kinberg, 1865 (Annelida: Errantia: Nereididae) from southern Africa, including a preliminary molecular phylogeny of the genus

Previous identifications and characterisations of southern African polychaete species are brief and many are based on northern hemisphere taxa. Hence, many species from family Nereididae were either misidentified or incorrectly synonymised with species from other regions, leading to an incomplete understanding of the nereidid diversity and biogeography in the region. As such, a thorough taxonomic review was conducted on museum specimens of the convoluted genus Neanthes Kinberg, 1865 present in southern Africa, with emphasis on those originally described from South Africa: Neanthes agulhana (Day, 1963), N. operta (Stimpson, 1856), N. papillosa (Day, 1963), and N. willeyi (Day, 1934). Morphological examinations based on the type material revealed that N. capensis is valid over N. willeyi, and N. agulhana is transferred to Nereis after redescribing the species; likewise, the alien status of both species in the Mediterranean Sea is questioned and rejected, respectively. The original type specimens of N. papillosa and N. operta are lost, although the former is recognised as valid based upon the original description, whereas the latter species is now considered indeterminable. Nereis polyodonta Schmarda, 1861, previously synonymised with N. operta, is reinstated and transferred to Neanthes. The current taxonomic status of the remaining Neanthes species recorded from southern Africa is pending a thorough re-evaluation. The phylogenetic status of this genus was investigated using a mitochondrial data set of Neanthes species globally, generated in this study or mined from GenBank and BOLD, in addition to other genera in Nereididae. Phylogenetic analysis suggests that Neanthes is polyphyletic; nonetheless, the majority of the relationships within the genus could not be resolved. A global scale assessment with an in-depth integrated approach in taxonomy is needed to distinguish this genus.