The Complete Mitogenome of the Lophius litulon (Lophioidei: Lophiidae) and Phylogenetic Implications

A specimen of L. litulon was collected from the coastal waters of Qingdao, China (35°35′N, 119°30′E) in 2021 and identified morphologically. The fish were stored at –80 °C and the muscle tissues were obtained from the Fishery Ecology and Biodiversity Laboratory (FEBL) of Zhejiang Ocean University (http://www.zjou.edu.cn/, Zhoushan, China). The specimen was kept by Tianyan Yang (hellojelly1130@163.com) under voucher number 20200206005. The complete mitochondrial DNA sequence of L. litulon was determined by the next-generation sequencing platform. MitoFinder was used for mitogenome assembly (Allio et al., 2020). The assembled mitogenome was annotated using MITOS2 (Donath et al., 2019).

The complete mitochondrial genome of L. litulon (GenBank Number: OL627348) was 16,430 bp in length, including 13 protein-coding genes, 22 transfer RNAs and two ribosomal RNA genes. The overall base composition was 26.96% for A, 30.13% for C, 17.58% for G and 25.33% for T, with a slight A+T bias of 52.29%. Gene arrangement was in accordance with the usual structure of vertebrate mitogenomes. All protein coding genes were encoded on the H-strand with the exception of ND6, and eight tRNA genes were transcribed from the L-strand.

A phylogenetic tree was reconstructed using the mitogenome of L. litulon produced in this study and six others available mitogenomes of family Lophiidae with Antennatus coccineus of family Antennariidae as the outgroup (Fig. 1). The 13 protein-coding genes of the eight mitogenomes were extracted by PhyloSuite 1.2.2. (Zhang et al., 2020) and aligned by MAFFT (Katoh and Standley, 2013). The aligned sequences were concatenated, and a maximum-likelihood analysis was conducted with IQTREE (Nguyen et al., 2015). The results suggested that sequences of Lophiomus setigerus (AP004413) and L. litulon (KJ020931) may be identifications. The four species of genus Lophius formed a monophyletic group first and clustered with genus Lophiodes and next with Sladenis, indicating a closer relationship between genus Lophius and Lophiodes.

The tree was inferred using IQ-TREE under the best-fit model GTR+F+I+G4 chosen according to BIC for 1,000 ultrafast bootstraps (Minh et al., 2013), as well as the Shimodaira Hasegawa like approximate likelihood-ratio test (Guindon et al., 2010).

We sincerely thank the reviewers for their constructive comments. We would like to thank Qi Liu for assistance in sample collection and data analysis.

This work was supported by the National Natural Science Foundation of China under Grant [41776171]; The Doctoral Research Foundation of Shandong Jiaotong University under Grant [BS201902051]; and The Province Key Research and Development Program of Zhejiang under Grant [2021C02047].

The genome sequence data of L. litulon that support the findings of this study are openly available in GenBank of NCBI at [https://www.ncbi.nlm.nih.gov] (https://www.ncbi.nlm.nih.gov/) under the accession number OL627348. The associated BioProject, SRA, and Bio-Sample numbers are PRJNA795006, SRR17477882, and SAMN24669163, respectively.

The fish was collected by trawling by local fishermen for commercial purposes. It was already dead when collected. No of the authors was involved in the collection of the fish. IRB approval was not needed because that no handing of live animals was involved.

The field studies did not involve any endangered or protected species. L. litulon is not protected by Chinese law. No fishing licence was required for the collection of samples from all locations. It is a commercial harvested species in China. The fish were collected by trawling by local fishermen for commercial purposes and were already dead when collected. None of the authors were involved in the collection of the fish. Animal Ethics Committee approval was not needed because no handing of live animals was involved.

The authors have declared no conflict of interest.