First fossil of the extant flat wasp genus Dissomphalus Ashmead, 1893 (Hymenoptera: Bethylidae: Pristocerinae)

Dissomphalus schubnelli n. sp., first fossil of the extant pristocerine genus Dissomphalus Ashmead, 1893, is described from the Earliest Eocene amber of Oise (France). This genus comprises 424 extant species distributed worldwide (except Antarctica). Dissomphalus schubnelli n. sp. is the third described Pristocerinae Mocsáry, 1881 from Oise amber, showing that this subfamily was probably already very diverse at that time.