The complete mitochondrial genome of Hemibagrus spilopterus (Teleostei: Siluriformes)

Abstract

Hemibagrus spilopterus is a tropical freshwater fish with high nutritional value. Here, we present the complete mitogenome of H. spilopterus. It was a circular molecule with 16,521 bp in length and contained 22 tRNA genes, 13 protein-coding genes, 2 rRNA genes, and a control region. The overall base composition was 31.68% A, 26.55% T, 26.77% C, and 15.01% G, with an AT content of 58.23%. The phylogenetic analysis showed that it was closely related to Hemibagrus sp. RCH and the genus Hemibagrus was not a monophyletic group.

Keywords:

• Siluriformes
• Bagridae
• Hemibagrus spilopterus
• mitogenome

The genus Hemibagrus (Teleostei: Siluriformes: Bagridae) consists of more than 40 valid species (Froese and Pauly 2019), presently, however, only six complete mitochondrial genome (mitogenome) data were available. Here, we determined the complete mitogenome sequence of Hemibagrus spilopterus, a tropical freshwater bagrid catfish with high-nutritional value and distributed in the lower Mekong River basin in Cambodia (Ng and Rainboth 1999). Samples were collected from Siem Reap in Cambodia (13.240391 N, 103.823090 E) and the specimens were deposited in the Southwest University Museum of Freshwater Fishes. The same approach as described in Zeng et al. (2012) was used to obtain the complete mitogenome of H. spilopterus. The sequences were aligned and analyzed using MEGA7 (Kumar et al. 2016). The phylogenetic analyses based on the maximum likelihood (ML) method and Bayesian inference (BI) were conducted using PhyML 3.0 (Guindon et al. 2010) and MrBayes 3.2.6 (Ronquist et al. 2012), respectively.

The complete mitogenome sequence of H. spilopterus was a circular molecule with 16,521 bp in length (GenBank accession No. JQ343983). It contained 22 tRNA genes, 13 protein-coding genes (PCGs), 2 ribosomal RNA genes, and a control region, which was identical to the other typical vertebrates (Peng et al. 2006). The overall base composition was 31.68% A, 26.55% T, 26.77% C, and 15.01% G, with an AT content of 58.23%. Some overlapping sites existed in PCGs, including the four notable overlaps between ATP8 and ATP6 (by 10 bp), ATP6 and COIII (by 1 bp), ND4L and ND4 (by 7 bp), and ND5 and ND6 (by 4 bp). Among the 13 PCGs, all genes used ATG as the start codon except COI, which used GTG. Six PCGs (ND1, COI, ATP8, ATP6, ND4L, and ND5) used TAA as stop codon; three PCGs (ND2, ND3, and ND6) used TAG as stop codon; while four PCGs (COII, COIII, ND4, and Cyt b) had incomplete stop codon T–. The length of the tRNAs ranged from 67 bp (tRNA-Cys and tRNA-Ser) to 75 bp (tRNA-Leu), which was consistent with the mitogenome of other species within the genus Hemibagrus (Zeng et al. 2012).

The results from the phylogenetic analysis strongly supported that the genus Hemibagrus is not a monophyletic group and H. spilopterus had a close relationship with Hemibagrus sp. RCH (Figure 1). In conclusion, the complete mitogenome of H. spilopterus can provide essential nucleotide data for further evolutionary analysis in family Bagridae.

Figure 1. Phylogenetic tree of H. spilopterus and the other 11 bagrid species based on maximum likelihood (ML) and Bayesian inference (BI) methods. The BI posterior probability and the ML bootstrap value are shown at the nodes.

Acknowledgments

We thank Ms. Dalin Ly (Royal University of Agriculture, Cambodia) for help in field sampling. We also thank Mr. Qing Zeng for the laboratory work.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China under [Grant no. 31872204].