Record of Two New Host Species, Tridentiger brevispinis and Gymnogobius urotaenia, for the Glochidia of the Freshwater Unionid Mussel Anodonta 'woodiana'

摘要

The freshwater unionid mussel Anodonta "woodiana" (a species group encompassing A. japonica and A. lauta) inhabits ponds, lakes, and rivers (Masuda & Uchiyama, 2004; Kondo et al., 2006). These are used as a spawning ground by bitterlings. In recent years, these habitats have declined in number and in places have disappeared, particularly in Kanagawa Prefecture in the Kanto area of central Japan. However, a mussel colony was discovered in a pond formed on the bank of the Sagami River in Kanagawa Prefecture (Itoh et al., unpublished data). The glochidia larvae of unionid mussels parasitize living fish. Glochidia metamorphose into juveniles after the end of their parasitic stage and become a part of the bottom life (Fukuhara et al., 1990). The breedingseason and host selectivity of A. "woodiana" have already been reported. Rhinogobius spp., Zacco spp. and mosquito fish, Gambusia affinis are known hosts of glochidia (Dudgeon & Morton, 1984; Fukuhara & Nagata, 1988; Kondo, 1987; Kondo, 1989; Kondo et al., 1996). In this study, we report the detection of two new host species (Tridentiger brevispinis and Gymnogobius urotaenid) for the glochidia of A. "woodiana".