1. Laboratory of Zoology, Graduate School of Agriculture, Kyushu University, Nishi-ku Motooka 744, Fukuoka 819-0395, Japan
2. Sensing System Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tosu, Saga 841-0052, Japan
3. Kuju Agriculture Research Center, Kyushu University, Taketa-shi 4045-4, Oita 878-0201, Japan
4. Department of Morphological Biology, Fukuoka Dental College, 2-15-1 Tamura, Sawara-ku, Fukuoka 814-0193, Japan