The genus Thomsonina is a small group of Proctotrupidae, with two described species in Palaearctic region: T. boops from Europe; T. scymni from Japan. These species are parasitoids of Scymnus (Coleoptera: Coccinellidae). Genus Nothoserphus was erected on the single species N. mirabilis Brues (1940) from Taiwan (Oriental). Since then two genera, Thomsonina Hellén (1941) from Europe (Western-Palaearctic) and Watanabeia Masner (1958) from Japan (Eastern-Palaearctic), proposed and the taxonomy was revised by Townes (1981) who synonymized Thomsonina and Watanabeia, including three species groups (boops- group, afissae-group and mirabilis-group). At present one genus classification Nothoserphus, is universally accepted. But, Masner (1958) suggested that Thomsonina and Watanabeia should be separated in two distinct genera from the Nothoserphus. This is supported by the different characters and biological data. In this study, the Authors are also agree to the Masner’s proposal and first report the genus Thomsonina from South Korea based on T. scymni. Also, we provide comparison of main different characters and host data for three genera.