The complete mitochondrial genome of the Japanese seahorse, Hipppocampus mohnikei (Syngnathiformes: Syngnathidae) and its phylogenetic implications

The entire genus Hipppocampus were listed on Appendix II of the CITES and Hipppocampus mohnikei was listed as Vulnerable in 1994. So far, morphology-based taxonomic methods have shown to be problematic and the exact species boundaries of many seahorses are obscure. In the present study, the complete mitochondrial genome of H. mohnikei was described. The total length is 16,513 bp in length, including 13 protein-coding genes (PCGs), two rRNA genes, 22 tRNA genes, one origin of replication on the light-strand (OL) and a putative control region. The overall base composition is 32.1% (A), 30.0% (T), 23.0% (C) and 15.0% (G) with a slight AT bias (62.0%). All of the PCGs use the initiation codon ATG except COI uses GTG. Most of them have TAA as the stop codon, except COII, COIII, ND3, ND4 and Cytb use an incomplete stop codon T. Additionally, the phylogenetic relationship of all Syngnathidae species available in the GenBank database was constructed, which will contribute to phylogenetic studies of Syngnathidae and further conservation strategies for seahorses.