The Chinese longsnout catfish ( Leiocassis longirostris Günther) is one of the most economically important freshwater fish in China. As wild populations have declined sharply in recent years, it is also a valuable model for research on sexual dimorphism, comparative biology, and conservation. However, the current lack of high-quality chromosome-level genome information for the species hinders the advancement of comparative genomic analysis and evolutionary studies. Therefore, we constructed the first high-quality chromosome-level reference genome for L. longirostris. The total genome was 703.19 Mb, with 389 contigs and contig N50 length of 4.29 Mb. Using high-throughput chromosome conformation capture (Hi-C) data, the genome sequences (685.53 Mb) were scaffolded into 26 chromosomes ranging from 17.36 to 43.97 Mb, resulting in a chromosomal anchoring rate for the genome of 97.44%. In total, 23 708 protein-coding genes were identified in the genome. Phylogenetic analysis indicated that L. longirostris and its closest related species P. fulvidraco diverged approximately 26.6 million years ago. This high-quality reference genome of L. longirostris should pave the way for future genomic comparisons and evolutionary research.
长吻鮠是中国重要的淡水经济鱼类之一，近年来，由于人工捕捞、水利工程修建等影响，野生长吻鮠资源衰减，数量急剧减少。作为进行性别二态性、比较生物学和保护生物学研究的有价值的模型，目前这一物种还缺乏用于比较基因组和进化分析的高质量染色体水平的参考基因组。因此，我们构建了首个长吻鮠高质量的染色体水平参考基因组。基因组大小为703.19 Mb，包含389个contigs，contig N50长度为4.29 Mb。利用高通量染色体构象捕获(Hi-C)数据，将685.53 Mb的基因组序列锚定到26条染色体上，长度为17.36~43.97 Mb，基因组的染色体锚定率为97.44%。长吻鮠基因组中共鉴定出23708个蛋白质编码基因、239.11 Mb重复序列（占全基因组的33.99%）和6303个非编码RNA。系统发育分析表明，长吻鮠和其亲缘关系最近的黄颡鱼大约在2660万年前开始分化。该研究获得的首个长吻鮠高质量参考基因组为今后的基因组比较和进化研究奠定了基础。.
Keywords: Chromosome-level genome assembly; Comparative genomics; Hi-C; Leiocassis longirostris; Nanopore sequencing.