The First Complete Mitochondrial Genome of the Flathead Cociella crocodilus (Scorpaeniformes: Platycephalidae) and the Phylogenetic Relationships within Scorpaeniformes Based on Whole Mitogenomes

Abstract

Complete mitochondrial genomes (mitogenomes) are important molecular markers for understanding the phylogenetics of various species. Although recent studies on the mitogenomes of the Scorpaeniformes species have been greatly advanced, information regarding molecular studies and the taxonomic localization of Platycephalidae is still sparse. To further analyze the phylogeny of Platycephalidae, we sequenced the complete mitogenome of Cociella crocodilus of the Platycephalidae family within Scorpaeniformes for the first time. The mitogenome was 17,314 bp in length, contained two ribosomal RNA genes (rRNAs), 22 transfer RNA genes (tRNAs), 13 protein-coding genes (PCGs), and two typical noncoding control regions (the control region (CR) and origin of the light strand (OL)). All PCGs used standard initiation codons ATG, apart from cox1. The majority of the tRNA genes could be folded into cloverleaf secondary structures, whereas the secondary structure of tRNASer (AGN) lacked a dihydrouridine (DHU) stem. The CR contained several conserved sequence blocks (CSBs) and eight tandem repeats. In addition, the phylogenetic relationship based on the concatenated nucleotides sequences of 13 PCGs indicated that the Platycephalidae species are relatively basal in the phylogenetic relationships of Scorpaeniformes. Our results may not only advance the origin and the evolution of Scorpaeniformes, but also provide information for the genetic evolution and taxonomy of the teleostean species.

Keywords: Cociella crocodilus; mitochondrial genome; phylogenetic analysis; platycephalidae; scorpaeniformes.

Figure 1

Relative synonymous codon usage (RSCU) of the C. crocodilus mitogenome.

Figure 2

The AT skew and GC skew in the PCGs of the C. crocodilus mitogenome.

Figure 3

Phylogenetic tree based on the nucleotide sequences of the 13 PCGs, using Bayesian inference (BI) and maximum likelihood (ML) methods, among Scorpaeniformes species. Perciformes fishes (P. novemaculeata (NC_024850.1) and S. knerii (NC_015987.1)) were used as outgroups. Numbers above the branches refer to Bayesian posterior probability values (blue numbers) and ML bootstrap values (red numbers).