ALLOZYME ELECTROPHORETIC ANALYSIS OF THE HEDISTE LIMNICOLA H-DIVERSICOLOR H-JAPONICA SPECIES COMPLEX (POLYCHAETA, NEREIDIDAE)

Three morphologically similar species of the polychaete genus Hediste [H. limnicola (Johnson, 1901), H. diversicolor (O.F. Muller, 1776), an d H. japonica (Izuka, 1908)] have been described, respectively, from t he west coast of North America, Europe, and Japan. Although these taxa are geographically isolated by oceans, the morphological criteria by which they can be separated are sufficiently variable as to make ident ification difficult. We have compared these three taxa biochemically u sing ten allozyme loci and have found that they are genetically distin ct and constitute valid species. H. japonica (collected in June 1990 f rom Kyushu, Japan) appears more closely related to H. limnicola (colle cted in July 1989 from two sites in California and two in Oregon, USA) than it is to H. diversicolor (collected in October-November 1989 fro m the Weser estuary and the Jadebusen in Germany). H. limnicola has be en recognized previously as a self-fertilizing hermaphrodite, but it i s quite polymorphic in the four populations examined and we suggest th at some cross-fertilization must occur in the field. Marked allele fre quency differences between the two H. diversicolor populations examine d, which were separated by only about 30 km, suggested that there was restricted gene flow between populations, or that there had been stron g short-term selection.