Abstract
BACKGROUND: The monotypic genus Acanopsilus (Hymenoptera: Diapriidae), is hitherto known only from Europe, where it is widely distributed. NEW INFORMATION: The genus is here recorded for the first time from South Korea and China, which constitutes the first formal record of the species from the entire Eastern Palaearctic region. A detailed redescription and photographs of Acanopsilus heterocerus (Haliday, 1857) are provided. Also, Acanopsilus brevinervis Kieffer, 1909 is proposed as junior synonym of Anommatium ashmeadi Mayr, 1856 (syn. nov.).