Dimorphothynnus' (Hymenoptera: Thynnidae: Rhagigasterini) newly recorded from the Northern Territory, Australia

The predominantly southern Australian genus Dimorphothynnus Turner is newly recorded from the Northern Territory, and two new species, D. fulvicrus and D. nigricrus, are described. Both species are relatively small in size, and only known from male individuals. A key to males of 15 species of Dimorphothynnus is given; that is, all but two of the known species. A key to females of eight species of Dimorphothynnus is given under the assumption of species fidelity of mates. Two new combinatins are made - Rhagigaster haemorrhoidalis Gu rin is transferred to Rhytidothynnus, and R. obtusus Smith is transferred to Dimorphothynnus.