There are many taxonomic problems in polychaete species names and solving confusing or inadequate taxonomic procedures is both time-demanding and extremely important. Our objective in this contribution was to analyse what is the current taxonomic situation for Nereis falsa de Quatrefages, 1866; it was based upon Nereis pulsatoria? Rathke, 1837 from the Black Sea, and it is currently regarded as having a very wide distribution. The species has been collected from different benthic substrates and even can be found on floating objects or marine turtles. Nereis falsa has been recorded from the Mediterranean Sea, the Eastern Atlantic along Africa, the Western Atlantic (Gulf of Mexico, Caribbean Sea, Brazil), and the Indian Ocean. However, despite the fact N. falsa was proposed as a species from the Black Sea, it has not yet been found there. How can we explain that a species is able to attain a very wide distribution and yet be missing from its type locality? After a careful study of previous publications and with our understanding of the systematics of nereidid polychaetes, we clarify the current situation by examining several related species and pointed out some nomenclatural issues. Our analysis indicates there is more than one species included under the same name, and in this contribution we propose some means to promote discussion and actions, and suggest some basic research for solving this issue
