Phylogenetic analysis of sooty grunter and other major freshwater fishes in the suborder Percoidei based on mitochondrial DNA.

Perciformes is the largest order of fishes and vertebrates. Sooty grunter (Hephaestus fuliginosus) is an economic fish species in the Terapontidae family of Percoidei, a suborder within Perciformes. To conduct molecular-level analysis of the phylogenetic relationships between sooty grunter and major freshwater fishes in Percoidei, we analysed the entire sooty grunter mitochondrial genome sequence and obtained the mitochondrial genome information of 19 fishes from Terapontidae, Serranidae, and Centrarchidae families in Percoidei from GenBank. The complete length of the sooty grunter mitochondrial genome was 16,770 bp; it encoded 13 proteins, 2 rRNAs, 22 tRNAs, and a displacement loop (D-loop). Other than ND6 and eight tRNA genes that are encoded by the light strand, the majority of genes are encoded by the heavy strand. The sequence and distribution of sooty grunter mitochondrial-encoded genes and non-coding segment were similar to those of most vertebrates. The results of neighbour joining, maximum parsimony, and Bayesian inference analyses of the complete mitochondrial genome and six genes, including cytochrome oxidase I, cytochrome B, 12S rRNA, ND2, ND4, and ND5, were consistent. In the phylogenetic trees, fishes in Terapontidae and Centrarchidae formed monophyletic clades, whereas those in Serranidae were divided into two clades, each containing Lateolabrax and Siniperca species. Among the three freshwater fish species in Terapontidae, the freshwater Terapontidae were more closely related to jade perch than with silver perch, suggesting that freshwater Terapontidae fishes originate from marine fishes. In addition, the phylogenetic results indicated that Micropterus salmoides salmoides and Micropterus salmoides floridanus in Centrarchidae should be designated as two independent species, and Siniperca in Serranidae should be considered an independent family. The sooty grunter mitochondrial genome sequence obtained in this study could be used to conduct population genetic diversity and germplasm resource studies. Furthermore, the phylogenetic analysis results of freshwater fishes in Percoidei could provide a molecular basis for cross-breeding.