<p>The freshwater mussel larvae (Unionida) undergo a parasitic stage, requiring attachment to other organisms, primarily fish. Some unionid species have been reported to parasitize both fish and amphibians. Studies on unionid parasitism involving amphibians are limited compared to those focusing on fish hosts. Particularly, the relationship between unionids and newts (Salamandridae) has not been extensively investigated. This study aimed to determine whether pond mussels (<i>Sinanodonta</i> sp.) can utilize Japanese newts (<i>Cynops pyrrhogaster</i>) as larval hosts through laboratory experiments. Freshwater gobies (<i>Rhinogobius</i> spp.) were also used as controls. The newts and gobies were artificially parasitized by the pond mussel larvae in a tank. The caged newts and gobies were maintained for 12&#xa0;d and the numbers of dropped larvae and metamorphosed juvenile mussels were counted daily. In the goby experiment, 38 larvae and 22 juvenile mussels were observed, resulting in a metamorphosis rate of 37%. In the newt experiment, 34 larvae and 36 juvenile mussels were observed, with a metamorphosis rate of 51%. No statistically significant difference was observed in metamorphosis rates between gobies and newts. These results demonstrated that the pond mussel larvae can successfully use the Japanese newt as a host, in addition to the freshwater goby, which is already recognized as a suitable host. This is the first documented study, outside North America, of unionid larvae parasitizing a salamandrid newt.</p>