1. Zoological Institute, University of Copenhagen, Universitetsparken 15, DK‐2100 Copenhagen, Denmark
2. Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, 3‐1‐100 Tsukide, Kumamoto 862‐8502, Japan
3. Aitsu Marine Biological Station, Matsushima‐cho, Amakusa, Kumamoto 861‐6102, Japan