In this study, 11 species of the genus Diduga Moore, [1887] are recognized from Thailand, including a new species, Diduga siamensis Bayarsaikhan & Heppner sp. nov., and one newly recorded species, D. scalprata Bayarsaikhan, Li & Bae, 2020. Illustrations of adults and genitalia of the additionally examined species are provided, with a checklist of known species of the genus from this country.