マイマイサンゴムシの自然界における終宿主の初記録

抄録

Around a hundred of brachylaimid trematodes were found from the small intestine of a carrion crow (Corvus corone) in Hokkaido, Japan. Based on the result of mitochondrial DNA barcoding, the parasites were identified as Brachylaima ezohelicis Nakao, Waki and Sasaki, 2017. This is the first record of a natural definitive host for B. ezohelicis. Although most of them were at the gravid adult stage, their body sizes varied widely. This species was described by using the specimens from experimentally infected mice. When compared with the original description, the crow-derived specimens were longer in total body length and has smaller testes and a wider uterine space, probably due to better development in the suitable host. The difference provides a cautionary tale about the plasticity of morphology in trematodes. Our finding strongly suggests that birds are more suitable than mammals in serving as definitive hosts for B. ezohelicis.