Characterization of the Complete Mitochondrial Genome of Nibea chui: Resolving a Taxonomic Controversy and New Phylogenetic Insights into Sciaenidae.

N. chui is an economically important marine fish species distributed along the coastal waters of China, renowned for its delicate flesh texture and high-quality dried swim bladder. However, its scientific name and taxonomic relationship with N. coibor have long remained controversial, hindering accurate resource assessment and germplasm management. To address this issue, we sequenced and annotated the first complete mitochondrial genome of N. chui (GenBank accession: PZ024444). The circular mitogenome is 16,504 bp in length and contains 37 typical genes, with gene arrangement, nucleotide composition (A + T content: 52.07%), and codon usage patterns consistent with general teleost characteristics. Phylogenetic analyses based on 13 concatenated protein-coding genes revealed that N. chui and N. coibor form a maximally supported monophyletic clade (bootstrap support = 100%), with a pairwise genetic distance of 0. These mitochondrial results strongly suggest that the two nominal taxa are very closely related and may represent the same species. However, formal taxonomic synonymy cannot be established on mitochondrial evidence alone and requires further evaluation through examination of type material and comparative morphological study. Gene-specific selection pressure analyses showed that most mitochondrial protein-coding genes were subject to purifying selection, with ATP8 exhibiting the highest mean ω among genes with ω < 1, whereas ND5 and ND6 showed elevated ω values that warrant cautious interpretation. This study provides essential mitochondrial genomic resources for future research on species delimitation, phylogeny, and conservation of this important sciaenid fish.