Morphological discrimination of the Ryukyu spiny rat (genus Tokudaia) between the islands of Okinawa and Amami Oshima, in the Ryukyu Islands, southern Japan
Morphological discrimination of the Ryukyu spiny rat (genus Tokudaia) between the islands of Okinawa and Amami Oshima, in the Ryukyu Islands, southern Japan
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日本南部琉球群岛冲绳岛和奄美大岛之间琉球刺鼠（德大鼠属）的形态区分
DOI：
10.3106/mammalstudy.26.17
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发表时间：
2001
期刊：
影响因子：
1
通讯作者：
Y. Kaneko
中科院分区：
文献类型：
--
作者：
Y. Kaneko
对来自日本南部琉球群岛（即南西群岛）奄美大岛和冲绳岛的 38 个博物馆标本进行了检查和测量，该标本属于 Tokudaia Kuroda 属，1943 年（啮齿目，鼠科）。根据三颗上臼齿的磨损情况，将每个样本分为五个年龄组（I-V）之一。冲绳刺鼠在第 III 和第 IV 组中平均具有比奄美大岛鼠更长、更宽的头骨和更长的臼齿列。然而，两个岛屿的头骨后部和中央部分的长度和宽度都没有不同。与相同大小的头部和身体长度（H&BL）或门牙-第三上磨牙长度（I-M3）相比，冲绳多刺鼠比奄美大岛多刺鼠具有更长的I-M3或更窄的颧弓。冲绳多刺鼠的第一上磨牙较宽（wM1≥1.9mm），而奄美大岛鼠的第一上磨牙wM1≤1.8mm。冲绳刺鼠的颅骨腭孔比奄美大岛鼠的颅骨腭孔位置更靠后。这些发现最终表明，奄美大岛和冲绳两个岛屿上的刺鼠种群除了具有不同的核型外，还具有明显不同的形态特征，因此它们应被视为不同的物种。奄美大岛的刺鼠应命名为 Tokudaia osimensis (Abe, 1933)，而冲绳的刺鼠应命名为 Tokudaia muenninki (Johnson, 1946)。
Thirty-eight museum specimens of the Ryukyu spiny rat, belonging to the genus Tokudaia Kuroda, 1943 (Rodentia, Muridae), from the islands of Amami Oshima and Okinawa, in the Ryukyu Islands (=the Nansei Islands), southern Japan, were examined and measured. Each specimen was classified into one of five age groups (I-V) determined by the wear of the three upper molars. The spiny rat of Okinawa has on average within age groups III and IV a statistically longer and wider skull and a longer molar row than that of Amami Oshima. However, neither the posterior nor the central parts of the skull length and width differ between the two islands. Against the same size of head and body length (H&BL) or incisor - the third upper molar length (I-M3), the spiny rat of Okinawa has longer I-M3 or narrower zygomatic arches than the spiny rat of Amami Oshima. The Okinawan spiny rat has a wider first upper molar (wM1≥1.9 mm), whereas that of Amami Oshima is wM1≤1.8 mm. The Okinawan spiny rat has the palatine foramen of the skull situated more posteriorly than that of Amami Oshima. These findings indicate conclusively that the spiny rat populations on the two islands of Amami Oshima and Okinawa have distinctly different morphological characteristics, in addition to having different karyotypes, and as such they should be regarded as distinct species. The spiny rat of Amami Oshima should be named as Tokudaia osimensis (Abe, 1933) while that of Okinawa should be known as Tokudaia muenninki (Johnson, 1946).