1. The University Museum, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0032, Japan
2. Laboratory of Wildlife Biology, Obihiro University of Agriculture and Veterinary Medicine, Obihiro 080-8555, Japan
3. The Kyoto University Museum, Kyoto University, Kyoto 606-8501, Japan
4. Department of Zoology, National Museum of Nature and Science, 4-1-1, Amakubo, Tsukuba, Ibaraki 305-0005, Japan