ABSTRACT We present a high‐quality, chromosome‐level reference genome for the endangered, endemic long‐armed scarab beetle Cheirotonus formosanus from Taiwan. Using PacBio HiFi and Hi‐C data, the nuclear assembly spans 600.9 Mb with N 50 of 69.5 Mb (largest scaffold 93.2 Mb). BUSCO completeness is 99.3% for the assembly and 97.7% for the genome annotation. The circularized mitochondrial genome (20,286 bp: GC content 30.74%) contains the canonical 37 genes, and HiFi long reads resolve tandem repeats in the control region that are intractable with short read platforms. A chromosome‐quotient approach with male (PacBio HiFi) and female (Illumina) reads assigned nine autosomal scaffolds, one X‐linked, and a putative Y‐linked scaffold (1.1 Mb). Historical demographic inferred independently from male and female genomes reveal identical trajectories. These results show a moderate effective population size ( N e ) through most of the last ~500 thousand years ago (kya) and increase beginning ~115 kya with a peak around ~50 kya, followed by a decline toward the Last Glacial Period and relative stability in the Holocene. Recent demographic inference and analysis of runs of homozygosity (ROH) indicate that while N e has remained low, the genomic landscape is dominated by short homozygous segments ( 5 Mbp) suggests that current inbreeding levels result from long‐term historical restriction rather than recent consanguineous mating. Together, these resources and workflows enable sex‐chromosome characterization, comparative mitochondrial genomics, and cross‐timescale demographic inference in C. formosanus and provide reusable pipelines for beetle genomics and conservation.
Chien et al. (Wed,) studied this question.