The complete mitochondrial genome of Echiniscus testudo (Heterotardigrada: Echiniscidae)

The complete mitchondrial genome of Echiniscus testudo, a cosmopolitan heterotardigrade collected in Japan, has been sequenced using a single molecule real-time (SMRT) sequencing long read after whole genome amplification from a single individual. The genome has a total length of 15,817 bp, consisting of 13 protein-coding genes, 20 tRNA, 2 rRNA genes, and an AT-rich control region. The nucleotide composition was extremely AT-rich, with 78.41% AT. Being in a different class of the phylum Tardigrada, there is a large sequence divergence from the previously reported mitochondrial genome of the eutardigrade Ramazzottius varieornatus, but the gene order of protein-coding genes are mostly conserved. This is the first report of a complete mitochondrial genome of a heterotardigrade.