Revision of the Palaearctic Gasteruption assectator aggregate, with special reference to Sweden (Hymenoptera, Gasteruptiidae).

The Palaearctic species of the Gasteruption assectator aggregate (Hymenoptera, Gasteruptiidae) are revised and three species are recognised. Two species are re-instated: Gasteruption boreale (Thomson, 1883), stat. n. and G. nigritarse (Thomson, 1883), stat. n., and both are excluded from the synonymy with G. assectator (Linnaeus, 1758). The general distribution of both species is given for Europe and in detail for Sweden. A key to the valid Palaearctic species of the Gasteruption assectator aggregate is given; key characters and primary types are illustrated. Four new synonyms are listed: Foenus fumipennis Thomson, 1883, Trichofoenus breviterebrae Watanabe, 1934, and Gasteruption margotae Madl, 1987, are synonymized with Gasteruption boreale (Thomson, 1883) and Gasteruption brevicauda Kieffer, 1904, with G. undulatum (Abeille de Perrin, 1879).