Morphological and genetic characterization of green-banded broodsacs of Leucochloridium (Leucochloridiidae: Trematoda) sporocysts detected in Succinea lauta in Hokkaido, Japan.

Green-banded broodsacs of Leucochloridium sporocysts were obtained from land snails, Succinea lauta, collected in Esashi, Esashi District, Hokkaido, Japan. The broodsacs were similar to those of L. paradoxum, which have never been found on the Japanese archipelago. Here, we compare morphological and molecular genetic characteristics of the green-banded broodsacs to those of L. paradoxum. The broodsacs described in this study and those of L. paradoxum showed three equal parts; however, band characteristics of the second parts differed. Moreover, the sequences of nuclear 18S and 28S rRNA genes of the Leucochloridium flukes were not identical with those of L. paradoxum, and the sequences of the mitochondrial cytochrome c oxidase subunit 1 gene were paraphyletic to the species. These findings suggest that the broodsacs described in this study were distinct from those of L. paradoxum. In the future, genetic analyses on adult flukes from avian hosts should be performed, upon precise identification according to morphology, in order to clarify relationships between adult flukes and sporocysts of Leucochloridium species occurring in Japan.