The species of four genera of Metopiinae (Hymenoptera: Ichneumonidae) in Britain,with new host records and descriptions of four new species

Two genera of Metopiinae are recorded for the first time from the British Isles, Ischyrocnemis Holmgren and Synosis Townes. An account is also given of a further two genera, Apolophus Townes and Stethoncus Townes, that have been recently recorded from Britain but remain little known. Apolophus and Synosis are shown to be koinobiont endoparasitoids of Lepidoptera larvae of the families Schreckensteiniidae and Yponomeutidae, respectively. Four species are described as new: Stethoncus monopicida sp. nov., Synosis caesiellae sp. nov., Synosis fieldi sp. nov., and Synosis parenthesellae sp. nov. A key to the Western Palaearctic species of Synosis is provided.