The Complete Mitochondrial Genome and Phylogenetic Position of the Pacific Spiny Dogfish Squalus suckleyi...

The Pacific spiny dogfish, Squalus suckleyi (Girard, 1854), is a benthopelagic small shark widely distributed across the North Pacific, caught in both commercial and bycatch fisheries throughout its range. Here we report the first mitochondrial genome of Squalus suckleyi, assembled from PacBio high-fidelity sequencing reads. The mitogenome (GenBank accession PZ086324) is 16,738 base pairs long and comprises the typical set of 37 mitochondrial genes found in vertebrates, including 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes and a control region. The overall nucleotide composition is AT-biased (A + T content of 61.17%), consistent with other elasmobranchs. Maximum-likelihood phylogenetic analysis based on the 13 protein-coding genes recovered S. suckleyi as sister to S. acanthias with maximum ultrafast bootstrap support. Pairwise non-synonymous to synonymous substitution rate ratios between S. suckleyi and S. acanthias ranged from 0 to 0.051 across all protein-coding genes, suggesting strong purifying selection on mitochondrial function in this recently diverged species pair. This mitogenome provides a high-quality genomic resource to support phylogeographic, evolutionary and management-oriented studies of Squalus suckleyi and more broadly the Squaliformes.