1. Graduate School of Human Development and Environment, Kobe University, Tsurukabuto 3-11, Nada, Kobe 657-8501, Japan
2. Department of Zoology, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan
3. National Museum of Nature and Science, Tsukuba, Ibaraki 305-0005, Japan
4. Department of Forest Science, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo 113-8657, Japan