Complete mitochondrial genome of Cultellus attenuatus and its phylogenetic implications

The complete mitochondrial genome of Cultellus attenuates , a new aquaculture species, was sequenced and compared with mitogenomes from seven species of Heterodonta bivalve mollusk in GenBank. The mitochondrial genome of C. attenuatus is 16888 bp in length and contains 36 genes, including 12 protein-coding genes, 2 ribosomal RNAs and 22 transfer RNAs, and all genes are encoded on the same strand. In comparison with C. attenuates , the mitochondrial genes of Sinonovacula constricta from the same family were not rearranged, but those of six other species from different families were rearranged to different degrees. The largest noncoding region of C. attenuatus is 1173 bp in length and has an A + T content of 68.24%, located between nad2 and trnK. The results of phylogenetic analysis show that C. attenuates and S. constricta belonging to Cultellidae cluster into one branch while two species of Solenidae ( Solen grandis and Solen strictus ) cluster as their sister taxa. In conclusion, we used the mitochondrial genome data to demonstrate the closest relationship between C. attenuatus and S. constricta in Heterodonta. These data not only contribute to the understanding of the phylogenetic relationship of Heterodonta but also serve as a resource for the development of genetic markers in aquaculture.