Unravelling a taxonomic puzzle: reinstating the South African Scolelepis capensis as distinct from Scolelepis squamata (Annelida: Spionidae)

Abstract

Scolelepis (Scolelepis) squamata (O. F. Müller, 1806) is a marine annelid previously considered cosmopolitan, but now recognized to be restricted to European waters. However, multiple species have recently been removed from synonymy with S. squamata, confirming that this species is not globally widespread. This study incorporated morphological and molecular data to show that Scolelepis (Scolelepis) capensis (McIntosh, 1924) from South Africa should be removed from synonymy with the nominal species. Phylogenetic analyses based on mitochondrial (COI), and nuclear (18S and 28S) markers show that S. capensis and S. squamata sensu stricto fall into separate clades. Scolelepis capensis is morphologically similar to S. squamata and S. agilis from the Atlantic coast of North America, but can be distinguished mainly by the shape and number of hooded hooks in the noto- and neuropodia, and the chaetigers where they first appear. This study contributes to ongoing taxonomic revisions of unresolved and pseudocosmopolitan polychaete species in South Africa, thus increasing our knowledge of local biodiversity. Further studies are necessary to evaluate the taxonomic status of S. capensis throughout southern Africa.