Molecular identification OF THE taxonomic status of Sinonovacula rivularis and genus Sinonovacula using mitochondrial COⅠ and 16S rRNA fragments

Partial sequences of mitochondrial gene COⅠ and 16S rRNA from five bivalve species (Sinonovacula rivularis, Sinonovacula constricta, Cultellus attenuatus, Cultellus scalprum and Solen grandis) were sequenced and analyzed. In the context of the sequences of other species of Solenoidae and Tellinoidea from GenBank, genetic distances were calculated. Phylogenetic trees (Neighbor-Joining) were constructed to determine the taxonomic position of Sinonovacula rivularis and genus Sinonovacula. The results showed that the A+T content in COⅠ or 16S rRNA fragments was far more than that of G+C. Sequence difference and genetic distance between S. rivularis and S. constricta in COⅠ and 16S rRNA reached a level of interspecies difference, and thus S. rivularis was confirmed to be a separated species of genus Sinonovacula. The topological structures of phylogenetic trees constructed on the basis of COⅠ and 16S rRNA fragments with Mya arenaria or Ostrea denselamellosa as the outgroup revealed that Sinonovacula, which was a genus of Pharella, should be incorporated into Solenoidae, but not Tellinoidea.