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SPECIES Tokudaia osimensis

Author:Abe, 1933.
Citation:Botany and Zoology, 1: 942.
Common Name:Amami-oshima Island Spiny Rat
Type Locality:Japan, Ryukyu Isls (= Nansei Isls), Amami-oshima Isl, Mt Kiyago-kan, village of Sumiyo.
Distribution:Known only by modern samples from Amami-oshima Isl.
Status:IUCN Endangered.
Comments: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., 1999b), a phenomenon found elsewhere among murids only in species of the arvicoline Ellobius (Just et al., 1995). Suzuki et al. (1999b: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.
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