The study of (): species-specific detection and phylogenetic relationship of , (Froelich, 1802).

is known as a significant intestinal trematode in various species of animals and humans. It presents complexities in terms of both the morphological and molecular biological data. This is the first study of the application of gene () as a target for studying the phylogeny and designing species-specific primer of . Adult trematodes were harvested from experimentally infected hamsters at 18 days of post-infection. Each worm was identified based on their morphological appearance. The novel primers were designed from other species to initially amplify region in . All sequence data of in five provinces of Central Thailand were used as the target for designing the species-specific primer for . The results revealed that gene can separate into two sister groups by geographical distribution, comprising the eastern and western area groups. Moreover, it also separates from other species, including two sibling species; and . In addition, we developed the high performance species-specific primer of . It can detect DNA from a single egg, as well as cercaria, metacercaria and adult stages of this trematode with no cross-reactions to other trematodes and their hosts. Therefore, this research is a positive initial step for the future study of . The future studies based on this gene should be continued with all species in revolutum complex to overcome the problems of systemic classification that arise in this complex group.