The Complete Mitochondrial Genome of Stichopus naso (Aspidochirotida: Stichopodidae: Stichopus) and Its Phylogenetic Position.

Abstract

The mitochondrial genome is widely used to study the molecular evolution of and perform phylogenetic analyses on animals. In this study, the complete mitochondrial genome (mitogenome) of Stichopus naso was sequenced. The mitogenome was 16,239 bp in length and contained 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), and 2 ribosomal RNA genes (rRNAs). The genome composition showed positive AT-skew (0.023) and negative GC-skew (−0.158). The order of the mitochondrial genes was consistent with those from the Stichopus and Isostichopus species, whereas it was different from those of other species of Aspidochirotida. The phylogenetic analysis, based on the nucleotide sequences of 13 PCGs through the methods of Bayesian inference (BI) and maximum likelihood (ML), indicated that S. naso has close relationships with S. horrens and S. monotuberculatus, and belongs to a member of Stichopodidae. Our study provides a reference mitogenome for further molecular evolution studies and phylogenetic research on sea cucumbers.