Burmese amber provides a unique window to the Cretaceous entomofauna, being the most prolific source of fossil insects for the period. Presently, about 61% of the Hymenoptera described from amber deposits in Myanmar are stinging wasps (Aculeata), including eight families known solely from Burmese amber. In the present work we describe the aculeate family †Trifionychidaefam. nov., as well as three new genera: †Prionaspidiongen. nov., including †Prionaspidion brevidenssp. nov. and †P. nanussp. nov.; †Trifionyxgen. nov., including †Trifionyx pilosussp. nov.; and †Trifionyximusgen. nov., including †Trifionyximus cracenssp. nov. We also reinterpret the fossil genus †Mirabythus, described based on rock impressions from the Yixian formation in China and originally attributed to Scolebythidae. †Mirabythus is moved to the new family, based mainly on the characteristic mandible; the large clypeus with a series of small denticles on the apical margin; the frons protruding over lateral portions of clypeus, directing the antennal sockets downwards below ocular level; and the presence of nine flagellomeres. Based on resemblances with fossil impressions attributed to †Bethylonymidae, we tentatively include the new family within the superfamily †Bethylonymoidea. Discovery of †Trifionychidaefam. nov. adds a novel lineage to the pool of aculeate families from the Cretaceous which did not survive to the present day.
