Not out of Africa: Spirobranchus kraussii (Baird, 1865) is not a global fouling and invasive serpulid of Indo-Pacific origin.
A common intertidal belt-forming serpulid Spirobranchus kraussii (Baird, 1865) was originally described from South Africa and subsequently reported from tropical and subtropical localities, mainly in the Indo-Pacific and Mediterranean Sea. It generally is assumed that the wide distribution of the nominal species is a result of human-mediated translocations. Here we provide a detailed illustrated re-description of S. kraussii based on the historical types and material freshly collected in South Africa from the type locality (Western Cape Province) and Eastern part of the country (KwaZulu-Natal Province). The description is accompanied by DNA sequence data (cyt b and 18S). Phylogenetic analysis of DNA sequences of specimens collected in South Africa, as well as farther afield in Australia, Japan, Hawaii, and Kuwait reveal several genetically distinct regionally distributed lineages. Closer comparative examination of morphological characters and environmental requirements reported in populations around the world has provided further evidence to reject the accepted status of this species as widespread in the Indo-Pacific. We conclude that Spirobranchus kraussii is a warm temperate/subtropical intertidal species restricted to South African coasts. It belongs to a globally distributed complex including some tropical fouling and invasive species. Further study into taxonomy and invasion ecology of this complex, especially in the Mediterranean, is needed.