show Abstracthide AbstractThe Tokunoshima spiny rat, Tokudaia tokunoshimensis, has highly unique sex chromosomes and a sex-determining mechanism. The sex chromosome constitution of this species is XO/XO, which is due to the absence of the Y chromosome similar to its closely related Amami spiny rat, T. osimensis. This species also lacks the SRY gene, which acts as the sex-determining gene in eutherian mammals. Therefore, we conducted whole genome sequencing and de novo assembly analysis for two aims: first, to utilize the information for the research of sex-determining mechanism and evolution of the Y chromosome, and second, to reserve the information as an important resource.