The paper gives the first record of a parasitoid (Hyposoter notatus Gravenhorst [Hymenoptera, Ichneumonidae, Campopleginae]) living on the interesting (very local) Iberian endemic species Plebejus pylaon hespericus (Rambur, 1839). Data about the biology of the parasitoid and photos of the parasitoid-host interaction are included. The study of the available bibliography and of several personal communications, indicates that this ichneumonid wasp is also the first parasitoid known to live on the "pylaon" group (Fischer-Waldheim, 1832) in Europe and in the Near East (probably for the whole of Eurasia). Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Land zones; Palaearctic region; Eurasia; Europe Plebejus pylaon group (Lycaenidae); Hymenopteran parasites; Hyposoter notatus; Annotated new record; Spain Plebejus pylaon hespericus (Lycaenidae); Hymenopteran parasites; Hyposoter notatus; Annotated new record; Spain; Granada; New parasite record Hyposoter notatus (Ichneumonidae); Lepidopteran hosts; Plebejus pylaon hespericus; Annotated new record; Spain; Granada; New host record none