1. Laboratory of Zoology, Graduate School of Agriculture, Kyushu University, Higashiku Hakozaki 6-10-1, Fukuoka 812-8581, Japan
2. Department of Morphological Biology, Division of Biomedical Sciences, Fukuoka Dental College, 2-15-1 Tamura, Sawara-ku, Fukuoka 814-0193, Japan
3. Department of Zoology, Okayama University of Sciences, Okayama 700-0005, Japan