Cephalic anatomy and three-dimensional reconstruction of the head of Catops ventricosus (Weise, 1877) (Coleoptera: Leiodidae: Cholevinae)

Adult head structures are well known in the coleopteran suborders Archostemata and Adephaga, whereas the available information is very fragmentary in the megadiverse Polyphaga, including the successful superfamily Staphylinoidea. In the present study, the cephalic morphology of the cholevine species Catops ventricosus is described in detail and documented. The results were compared to conditions occurring in other polyphagan lineages, especially staphylinoid and scarabaeoid representatives. Specific external features documented in Catops and potential autapomorphies of Leiodidae include a five-segmented antennal club with a reduced eighth antennomere and the presence of periarticular grooves filled with sensilla on antennomeres 7, 9, and 10. The firm connection of the head and pronotum is possibly an apomorphy of Cholevinae. The monophyly of Cholevinae excluding Eucatopini and Oritocatopini is supported by the apical maxillary palpomere as long as or shorter than the subapical one, and the presence of cryptic pore plates on the surface of these palpomeres—a feature described and documented here for the first time. The internal cephalic structures of Catops are mostly plesiomorphic, as for instance the complete tentorium. The pattern of the muscles is similar to what is found in other staphylinoid taxa. The unusual maxillary muscle “Mx” is likely a groundplan apomorphy of the clade Staphyliniformia + Scarabaeoidea. M. hypopharyngomandibularis (M13) was identified in Catops and is ancestral for Coleoptera, even though it is often missing. The same applies to M. tentoriohypopharyngalis (M42).The PhD study of CAC as well as his research internship at the Friedrich-Schiller-Universität was funded by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) (2012/19002-0 and 2014/22088-0). PG was also supported by FAPESP (2013/06314-7) and MY by the DAAD, which is also gratefully acknowledged. The stay of IR in the Phyletisches Museum in Jena was funded by a Salvador de Madariaga grant (PRX14/00583).Peer reviewe