Ryukyu spiny rat

{{Short description|Species of rodent}}

{{speciesbox

| name = Ryukyu spiny rat

| status = EN | status_system = IUCN3.1

| status_ref={{cite iucn |author=Ishii, N. |date=2016 |title=Tokudaia osimensis |volume=2016 |page=e.T21973A22409638 |doi=10.2305/IUCN.UK.2016-1.RLTS.T21973A22409638.en |access-date=15 November 2021}}

| genus = Tokudaia

| species = osimensis

| authority = (Y. Abe, 1934)

| range_map = Tokudaia osimensis distribution.png

| synonyms =

}}

The Ryukyu spiny rat (Tokudaia osimensis) is a species of rodent in the family Muridae.{{MSW3 Muroidea | id = 13001850 | page = 1513}} Endemic to Amami Ōshima island in the Amami Islands of the Ryukyu archipelago of Japan, its natural habitat is subtropical moist broadleaf forest. The karyotype has an odd diploid number, 2n = 25. Like its relative T. tokunoshimensis, it has lost its Y chromosome and SRY gene.{{cite news|last=KAYOKO GEJI|title=Y chromosome losing all genes, but men won't become extinct|url=http://ajw.asahi.com/article/behind_news/social_affairs/AJ201208230009|access-date=11 January 2014|newspaper=The Asahi Shimbun|date=August 23, 2012|url-status=dead|archive-url=https://web.archive.org/web/20140111165735/http://ajw.asahi.com/article/behind_news/social_affairs/AJ201208230009|archive-date=11 January 2014}}

The species is threatened by habitat destruction and fragmentation, predation by feral cats and dogs and introduced mongooses, and competition with introduced black rats.