Genetic Divergence of Mussels (Mollusca, Mytilidae) Based on the 28S rRNA, 18S rRNA, and H3 Nuclear Gene Sequences

On the basis of nucleotide sequences of three nuclear genes and using molecular phylogenetic and evolutionary genetic approaches, the phylogeny of the main representatives of one of the largest taxa of bivalve mollusks, the family Mytilidae, was studied, and its system and taxonomy were refined. A phylogenetic system for the family Mytilidae and closely relative taxa of the order Mytilida, which currently has no consensus among specialists on the basis of traditional characters, is presented. Using nucleotide sequences of the 28S rRNA, 18S pRNA, and histone H3 genes, this consensus was established by the study of Mytilidae. Some concerns of mussel systematics were resolved; in particular, the monophyly of the family Mytilidae Rafinesque, 1815 was established with the strongest support for the subfamily Mytilinae Rafinesque, 1815. The data obtained disprove Distel's conclusion on polyphyly of the subfamily Mytilinae Rafinesque, 1815. Isolation of the taxa in the rank of the Modiolinae G. Termier & H. Termier, 1950 and Bathymodiolinae Kenk & Wilson, 1985 subfamilies in the family Mytilidae and also the family Septiferidae Scarlato et Starobogatov, 1979 was confirmed, although the rank of the later taxon is not universally recognized and it remains to be clarified in an additional study.