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 osimensis (Abe 1933) [Rattus] jerdoni Abe 1933 , Botany and Zoology, Vol. 1: 942 . Type Locality: Japan , Ryukyu Isls (= Nansei Isls), Amami-oshima Isl, Mt Kiyago-kan, village of Sumiyo. Vernacular Names: Amami-oshima Island Spiny Rat . Distribution: Known only by modern samples from Amami-oshima Isl. Conservation: IUCN – Endangered. Discussion: Abe, 1934, J. Sci. Hiroshima Univ., ser. B, div. 1, 3:107, is the usual date and citation for osimensis (see Corbet and Hill, 1992 and Musser and Carleton, 1993 ), but the name was proposed a year earlier in a different journal according to Kaneko (2001) ; also see Kaneko and Maeda (2002) .The unique chromosomal complement of this species (2n = 25, with no X in the female or visible Y in the male) first documented by Honda et al. (1977) and corroborated by Kimiyuki et al. (1989) . Testes devopment depends upon inheritance of the Sry gene encoded on the Y chromosome, but T. osimensis lacks this gene ( Suzuki et al., 1999 b ), a phenomenon found elsewhere among murids only in species of the arvicoline Ellobius ( Just et al., 1995 ) . Suzuki et al. (1999 b :590) noted that to describe the mechanism of sex determination in these species "will require a more precise genetic analysis... and will bring us new information on sex determination mechanisms, evolution, and plasticity." Reviewed by Kaneko (1994) , who also provided a beautiful color photograph of the live rat.