A ceraphronid wasp genus, Masner Mikó & Deans, gen. n., with one species, M. lubomirus Deans & Mikó, sp. n. is described from Australia and Fiji based on male specimens. This new genus challenges previous definitions of the two extant ceraphronoid families by sharing some character states with Megaspilidae (the presence of an expanded pterostigma and an occipital depression) and other character states with Ceraphronidae (the presence of uniramous anterior protibial spur, presence of a comb of the spur on the pro- and mesotibial spurs, a single mesotibial spur, an undivided synsternite, the presence of axillular setae, presence of Waterston’s evaporatorium and the fusion of the parossiculus with the gonostipes). Masner is distinguishable from all other Ceraphronoidea by the sensillar patch present on flagellomere 5 but absent from flagellomeres 6–9 and the presence of a dorsally visible depression surrounding anterior part of the petiole. The limits of Ceraphronidae and Megaspilidae are reviewed, and we provide new characters for family level diagnosis and classification. We also hypothesize that Masner is sister to the remaining Ceraphronidae.