First record of the natural first intermediate host of Lutztrema attenuatum (Dujardin, 1845), a cosmopolitan trematode of passerine birds

Abstract

The dicrocoeliid trematode Lutztrema attenuatum (Dujardin, 1845) has been reported from its definitive hosts, passerine birds worldwide, whereas its larvae have never been detected in natural fields. In this study, 41 adults of Lu. attenuatum were obtained from dead specimens of Turdus pallidus Gmelin, 1789 and T. eunomus Temminck, 1831, and the partial sequence of the mitochondrial COI gene and nuclear 28S rDNA were determined from one of the specimens as DNA barcodes. Furthermore, during a land snail survey in Tokyo, Japan on 11 August 2021, dicrocoeliid sporocysts and cercariae were detected from the achatinid Allopeas satsumense (Pilsbry, 1906). The partial COI sequence of the sporocysts showed a p-distance value of less than 1.4% to that of the adult Lu. attenuatum. The sporocyst was identified molecularly as Lu. attenuatum based on an empirical intraspecific genetic variation in dicrocoeliids, and thus A. satsumense found to be its first intermediate host. We also provided DNA barcodes to an adult specimen of Lyperosomum sp. (Dicrocoeliidae) detected from the same dead specimen of T. pallidus.