Abstract

The taxonomic identity of mussels in the southern hemisphere is still unclear, and the Mytilus that inhabit on the Pacific coast of South America has been considered by different authors as M. chilensis, M. edulis, M. edulis chilensis and M. galloprovincialis. To clarify the taxonomic identity of these mussels four samples from the northern limit of the distribution of Mytilus were taken as well as European control samples of M. edulis and M. galloprovincialis for comparison. Thirty allozyme loci were studied and 9 loci (Aco-1, Ap-1, Est-D, Gpi, Idh-1, Lap-1, Mpi, Me-2 and Odh) were partially diagnostic between the European M. edulis and M. galloprovincialis control samples, as previously reported. Chilean samples showed for four of the above partially diagnostic loci intermediate frequencies for typical alleles of M. edulis and M. galloprovincialis between those of the control samples, but they were closer to those of M. edulis for Ap-1 and Mpi and to those of M. galloprovincialis for Aco-1 and Est-D. The locus Lap-1 showed allele frequencies similar to those of M. edulis, whereas the most frequent allele of the loci Gpi, Idh-1 and Odh was that typical of M. galloprovincialis but at a higher frequency. Moreover, the partially diagnostic loci Me-2 and Lap-2, Pgm-2 and Pp showed important differences with regard to the control populations. Genetic distances, dendrograms and multidimentional scaling as well as principal component analysis on allele frequencies and factorial correspondence analysis on individual genotypes showed that South American samples were genetically closer to European M. galloprovincialis than to M. edulis but having particular and characteristic allele frequencies.