A Whole-Genome Survey and the Mitochondrial Genome of Provide Insights into Its Phylogenetic Relationships in Priacanthiformes.

, a deep-sea snake fish, is primarily found in the Indo-west Pacific region, including India, Korea, Japan, and the South China Sea. The taxonomic classification of based on morphological characteristics remains inaccurate and unclear. In this study, we utilized next-generation sequencing to generate comprehensive genomic data for . The estimated genome size of was 422.95 Mb, with a heterozygosity ratio of 1.02% and a sequence repeat ratio of 22.43%. Our analysis suggested that is diploid, and the draft genome assembly consists of 1,059,784 contigs with a contig N50 of 1942 bp. We identified a total of 444,728 simple sequence repeats in the genome of . Furthermore, we successfully assembled the complete mitochondrial genome (16,439 bp) of , which included 13 protein-coding genes, 22 tRNA genes and 2 rRNA genes. Phylogenetic analysis based on mitochondrial genomes revealed that is closely related to and , providing evidence that the family Cepolidae belongs to the order Priacanthiformes. Population size dynamics analysis indicated that experienced a bottleneck effect during the Pleistocene Glacial Epoch, likely due to the changes in glacial cycles and sea level fluctuations since ~800 Kya.