Bonse, Susanne; Schmidt, Hartmut; Eibye-jacobsen, Danny; Westheide, Wilfried. (1996). Eulalia viridis (Polychaeta: Phyllodocidae) is a complex of two species in northern Europe: Results from biochemical and morphological analyses. Cahiers de Biologie Marine. 37(1), 33-48.
Given that relatively simple electrophoretic methods have repeatedly proven their usefulness in sorting out difficult species complexes, it seemed a promising approach to apply them to various local populations of E. viridis in order to test whether this species name is in fact being used for more than a single species. Specimens were collected from geographically separated local populations in the Channel region (Saint-Efflam, Granville) and the North Sea (Newcastle, Norderney, Helgoland, Helsingor and Tjarno). Particular enzymes and general protein patterns of individual animals were compared by means of isoelectric focusing (IEF), and the animals were examined for morphological differences. Distinct differences between the IEF band patterns of specimens from the western and eastern sites were indeed observed, and these were found to be correlated with differences in the morphology and size of the dorsal cirri and the size of the proboscideal papillae. Therefore, it became necessary to subdivide the material into two species, E. viridis for that found in Sweden, Denmark and Germany and E. clavigera for that from France and England.