Two new parasitoid wasp species of the Australasian genus Orussobaius (Hymenoptera: Orussidae)

Two new species of the rarely collected Australasian parasitoid wasp genus Orussobaius Benson, 1938 are described and considered in a phylogenetic context. Orussobaius nielspederi Blank & Vilhelmsen, n.sp. from Yamdena, Tanimbar Islands is characterized by extensive metallic sheen on the dorsal part of the abdomen in the females. Orussobaius bicolor Vilhelmsen & Blank, n.sp. from Queensland, Australia has distinct contrasting body colouration, with head, thorax and abdominal tergum 1 black and the remainder of the abdomen reddish brown; the fore wings are hyaline. The two new species have been included in a data set for the rest of the Orussidae. Regardless of the analytical settings, the topology for Orussobaius retrieved is always (O. caligneus + O. mesembrinus) + (O. bicolor + (O. minutus + O. wilsoni + (O. badius + O. minutissimus)+ (O. nielspederi + O. paniculus))). O. nielspederi is the third species of Orussobaius that has been recorded outside mainland Australia, where seven out of the nine known species in the genus have been found. Apparently, the genus has not been able to disperse outside the land masses connected by the Sahul Shelf as it has not been recorded outside the Australasian Region.