The maxillo-labial complex of Sparasion (Hymenoptera, Platygastroidea)

Hymenopterans have evolved a rich array of morphological diversity within the maxillo-labial complex. Although the character system has been extensively studied and its phylogenetic implications revealed in large hymenopterans, e.g. in Aculeata, it remains comparatively understudied in parasitoid wasps. Reductions of character systems due to the small body size in microhymenoptera make it difficult to establish homology and limits the interoperability of morphological data. We describe here the maxillo-labial complex of an ancestral platygastroid lineage, Sparasion, and provide an ontology-based model of the anatomical concepts related to the maxillo-labial complex (MLC) of Hymenoptera. The possible functions and putative evolutionary relevance of some anatomical structures of the MLC in Sparasion are discussed. Anatomical structures are visualized with Confocal Laser Scanning Microscopy. Copyright Ovidiu Alin Popovici et al.