Genetic differences between two allopatric populations (or sibling species) of the polychaete genus Marenzelleria in Europe

Genetic variation and differentiation in introduced European populations of the spionid polychaete Marenzelleria viridis were studied by enzyme electrophoresis. Major differences exist between the North Sea and Baltic populations, although the genetic structure within each of them is largely homogeneous. Nine loci were studied, five of which are of diagnostic value. The genetic distance between the North Sea population and the Baltic population is 0.891-0.897. Genetic differences of this extent suggest that the Marenzelleria populations found in the North Sea and Baltic Sea are two different species.