Complete mitochondrial genome of sea slug Phyllidiella sp.(Phyllidiidae, Phyllidiella) from the South China sea and its phylogenetic implications

Abstract Background The complete mitochondrial genome and phylogenetic relationship of the newly recorded species of sea slug from the South China sea has not been reported. The taxonomic status of sea slug is not clear. Methods and results The whole mitochondrial genome of a newly recorded species of sea slug from the South China sea ( Phyllidiella sp) was determined by Illumina Hiseq4000 sequencing and denovo assembly. The mitochondrial genome of Phyllidiella sp was 14,677 bp in length, including 13 protein-coding genes (PCGs), 2 rRNAs, and 22 tRNAs. In the mitochondrial DNA of Phyllidiella sp the base composition of mitogenome is 30.37% for A, 37.30% for T, 15% for C, and 17.33% for G, and the content of AT was 67.67%. Beside the two kinds of tRNA-Ser, the secondary structure of all tRNAs had a typical cloverleaf structure. In comparison with Phyllidiella pustulosa and Phyllidia ocellata from the same family, the mitochondrial genes of Phyllidiella sp. was not rearranged. The phylogenetic results showed that Phyllidiella sp. and Phyllidiella pustulosa from the same genus clustered into one cluster. Moreover, the genus Phyllidiella clade was sister relationship to the Phyllidia clade. Conclusions Our findings demonstrate that Phyllidiella sp. belongs to the family Phyllidiidae, due to the morphological identification. This study provides molecular information for the phylogenetic analysis of the taxonomic status of sea slugs.