Comparative studies of the complete mitochondrial genomes of four Paphia clams and reconsideration of subgenus Neotapes (Bivalvia: Veneridae)

► Mitogenome reorganization is not random but follows phylogenetic trends. ► The two trnM genes among five venerids may recently origin following duplication. ► VNTRs in the four Paphia mitogenomes have a common origin. ► Taxonomic basis of Neotapes should be “smooth surface” but not “undulated lines”.