The complete mitogenome of Phymorhynchus sp. (Neogastropoda, Conoidea, Raphitomidae) provides insights into the deep‐sea adaptive evolution of Conoidea

The deep‐sea environment is characterized by darkness, hypoxia, and high hydrostatic pressure. Mitochondria play a vital role in energy metabolism; thus, they may endure the selection process during the adaptive evolution of deep‐sea organisms. In the present study, the mitogenome of Phymorhynchus sp. from the Haima methane seep was completely assembled and characterized. This mitogenome is 16,681 bp in length and contains 13 protein‐coding genes, 2 rRNAs, and 22 tRNAs. The gene order and orientation were identical to those of most sequenced conoidean gastropods. Some special elements, such as tandem repeat sequences and AT‐rich sequences, which are involved in the regulation of the replication and transcription of the mitogenome, were observed in the control region. Phylogenetic analysis revealed that Conoidea is divided into two separate clades with high nodal support. Positive selection analysis revealed evidence of adaptive changes in the mitogenomes of deep‐sea conoidean gastropods. Eight residues located in atp6, cox1, cytb, nad1, nad4, and nad5 were determined to have undergone positive selection. This study explores the adaptive evolution of deep‐sea conoidean gastropods and provides valuable clues at the mitochondrial level regarding the exceptional adaptive ability of organisms in deep‐sea environments.