Order Rodentia - Family Muridae Author Wilson, Don E. Author Reeder, DeeAnn text 2005 The Johns Hopkins University Press Baltimore Mammal Species of the World: a Taxonomic and Geographic Reference (3 rd Edition), Volume 2 1189 1531 book chapter 0-8018-8221-4 10.5281/zenodo.7316535 Tokudaia muenninki Johnson 1946 Tokudaia muenninki Johnson 1946 , Proc. Biol. Soc. Wash., 59: 170 . Type Locality: Japan , Ryukyu Isls (= Nansei Isls), N Okinawa Isl, Hentona (western coast). Vernacular Names: Okinawa Island Spiny Rat . Distribution: Known by modern specimens from N Okinawa , and late Pleistocene and Holocene samples from Okinawa and adjacent island of Le-jima ( Kawamura, 1989 ; Kowalski and Hasegawa, 1976 ). Conservation: IUCN – Critically Endangered. Discussion: Originally described as a subspecies of T. osimensis ( Johnson, 1946 a ) , but chromosomal evidence (2n = 44 for muenninki , 2n = 25 for osimensis ), as well as external and cranial morphology distinguish muenninki as a separate species ( Kaneko, 2001 ; Tsuchiya, 1981 , Tsuchiya et al., 1989 ). Based upon molar measurements, Kaneko (2001) suggested that the late Pleistocene specimens identified as T. osimensis by Kowalski and Hasegawa (1976) and Kawamura (1989 , 1991 , 1994 ) actually represent T. muenninki and T. osimensis , indicating that both species occurred on Okinawa during late Pleistocene. Kaneko cautioned, however, that the fossils must be reexamined to confirm these possible identifications. A population of Tokudaia also occurs on Tokuno-shima Isl, south of Amami-oshima and north of Okinawa . Chromosomal distinctions between osimensis (2n = 25) from Amami-oshima, muenninki (2n = 44) from Okinawa , and the population from Tokuno-shima Isl (2n = 45) were documented by Honda et al. (1978) , Tsuchiya (1981) and Tsuchiya et al. (1989) . While that data suggested the Tokuno-Shima Isl sample to represent a third species, Kaneko unfortunately could not include the population in his morphometric study because it is protected and no voucher specimens have been preserved. Significant differences between samples from Tokuno-shima and Amami-oshima in mtDNA cytochrome b sequences and restriction fragment length polymorphism in the nuclear ribosomal RNA gene also led Suzuki et al. (1999 a ) to regard the two insular populations as independent species. Molecular data from T. muenninki and morphological information from the population on Tokuno-Shima Isl must be analyzed to test the results implied by present chromosomal information .