Adult head structures of Lepicerus inaequalis were examined in detail and interpreted functionally and phylogenetically. The monogeneric family clearly belongs to Myxophaga. A moveable process on the left mandible is an autapomorphy of the suborder. Even though Lepiceridae is the "basal" sistergroup of the remaining three myxophagan families, it is likely the group which has accumulated most autapomorphic features, e.g. tuberculate surface structure, internalised antennal insertion, and a specific entognathous condition. Adults of Lepiceridae and other myxophagan groups possess several features which are also present in larvae (e.g., premental papillae, semimembranous mandibular lobe). This is probably related to a very similar life style and has nothing to do with "desembryonisation". Lepiceridae and other myxophagans share a complex and, likely, derived character of the feeding apparatus with many polyphagan groups (e.g., Staphyliniformia). The mandibles are equipped with large molae and setal brushes. The latter interact with hairy processes or lobes of the epi- and hypopharynx. This supports a sistergroup relationship between both suborders.
Internal and external features of the head of Ascioplaga mimeta (Coleoptera: Archostemata) were studied with micro X-ray computertomography (µCT) and nuclear magnetic resonance imaging (NMRI). These methods allowed the reconstruction of the entire internal anatomy from the only available fixed specimen. The mouthparts and their associated musculature are highly derived in many aspects. Their general configuration corresponds to that of Priacma serrata (the only other archostematan studied in comparable detail). However, the mandible-maxilla system of A. mimeta is built as a complex sorting apparatus and shows a distinct specialisation for a specific, but still unknown, food source. The phylogenetic analysis resulted in the identification of a new monophylum comprising the genera [Distocupes + (Adinolepis +Ascioplaga)]. The members of this taxon are restricted to the Australian zoogeographic region. The most prominent synapomorphies of these three genera are their derived mouthparts.