The complete mitochondrial genome of the short snouted seahorse Hippocampus hippocampus Linnaeus 1758 (Syngnathiformes: Syngnathidae) and its phylogenetic implications

The short-snouted seahorse Hippocampus hippocampus Linnaeus 1758 is a native European seahorse within the Family Syngnathidae. To facilitate its conservation genetic studies, the complete mitochondrial genome of H. hippocampus was determined and analyzed. The circular genome of the H. hippocampus is 16,529 bp in length, with a overall nucleotide composition of 32.03, 24.06, 15.05 and 28.86% for A, C, G and T, respectively, indicating an obvious AT rich feature (60.89%). Similar to other Hippocampus species, it contains 13 protein-coding genes (PCGs), 22 tRNA genes, two rRNA genes, one origin of replication on the light-strand and one control region. The 13 PCGs encode 3798 amino acids in total, most of which use the initiation codon ATG except COI gene starts with GTG. For the stop codon, six genes use an an incomplete stop codon T, while the other seven genes apply TAA or TAG as the stop codon. The lengths of 12S and 16S rRNA are 937 and 1695 bp, respectively. Phylogenetic tree analysis based on the complete mitochondrial genome showed that H. hippocampus is closely related to the lined seahorse H. erectus. This work provides basic genetic data of H. hippocampus which will be helpful for further researches on genetic diversity and species identification.