Configuration of radula sac of nine species of Nipponacmea A N. gloriosa, RM32355, Ibusuki, Kagoshima (41) B N. fuscoviridis, RM32354, Akune, Kagoshima (39) C N. boninensis, RM31817, Chichijima Is., Ogasawara (43) D N. schrenckii, RM31906, Kazamaura, Aomori (6) E N. concinna, RM32353, Nagatamachi, Nagasaki (35) F N. radula, RM32363, Akune, Kagoshima (37) G N. nigrans, RM32362, Kushimoto, Wakayama (20) H N. habei, RM32356, Tateyama, Chiba (13) I N. teramachii, RM31928, Suo-Oshima, Yamaguchi (30). Scale bars: 5 mm.