A new genus and species, Burmorussus mirabilis, is described based on two specimens from the mid-Cretaceous Burmese amber, and considered to be a specialized parasitic wasp of wood-living hosts. The new taxon is characterized by an orussid-like ocellar crown, big eyes, antennae attached well above the clypeus, and antennal grooves or ventral transverse frontal carinae absent. Additionally, all legs carry a prominent lanceolate lobe on the third tarsomere. A similar structure is found, but organized differently, in Recent Orussidae and Stephanidae, serving as part of a vibration analyser. Although sharing some characters with families Karatavitidae, Orussidae and Paroryssidae, this new taxon cannot be assigned to any of these families. We propose a new monotypic family Burmorussidae and assign it to the superfamily Orussoidea. A phylogenetic analysis confirms the monophyly of Orussoidea, which occurs a sister group to Apocrita.