Revision of Trassedia (Hymenoptera: Ceraphronidae), an Evolutionary Relict with an Unusual Distribution

Ceraphronoidea is composed of two, seemingly well-defined families, Ceraphronidae and Megaspilidae. The position of Trassedia Cancemi 1996 within the superfamily is unclear, as this genus shares characteristics of both families. For instance, Trassedia possess both the pterostigma form characteristic of Megaspilidae, and the Waterston's evaporatorium, a structure unique to Ceraphronidae. Trassedia was known only from a single specimen of T. luapi Cancemi 1996 from Madagascar. We describe nine new species: Trassedia australiensis Mikó and Masner sp. nov. (Australia), Trassedia yanegai Mikó and Trietsch sp. nov. (Thailand), Trassedia brasiliensis Masner and Mikó sp. nov. (Brazil), Trassedia nigra Masner and Mikó sp. nov. (Brazil), Trassedia nigrorufus Mikó and Masner sp. nov. (Panama), Trassedia guianensis Mikó and Masner sp. nov. (French Guiana), Trassedia angustioculus Mikó and Masner sp. nov. (French Guiana), and Trassedia pilosus Masner and Mikó sp. nov. (Costa Rica), and Trassedia gauldi Mikó and Masner sp. nov. (Costa Rica and Brazil). To illuminate the morphological concepts presented here, we provide SR-μCT and confocal laser scanning microscopy (CLSM)-based 3D reconstructions. The Waterston's organ is sexually dimorphic in Trassedia; it is unpaired in males and paired in females. We describe modifications of the metasoma apex that align with the enlarged hind tarsi, a leg phenotype peculiar to Trassedia and the unique subdivision of the first valvifer. We report the presence of the occipital depression in Trassedia and describe how this structure is involved in a secondary articulation between the head and the mesosoma. We discuss the possible function and phylogenetic relevance of the pterostigma in Ceraphronoidea. Based on its Southern Hemisphere distribution we hypothesize that Trassedia's presence predates the break-up of Gondwana.