Ademosynidae (Insecta: Coleoptera): A new concept for a coleopteran key taxon and its phylogenetic affinities to the extant suborders

Abstract

†Ademosynidae is a controversial extinct family of Coleoptera, first discovered in Australian Upper-Triassic deposits. The last known representative is known from the Early Jurassic of Kirghizstan. Type material from the collection of Moscow Paleontological Institute is re-described here and interpreted phylogenetically. The results show that the family as presently defined is not monophyletic, but possibly divided among two of four extant coleopteran suborders. We establish a new narrower concept of the family including the genera Ademosyne Handlirsch, 1906, Dolichosyne Ponomarenko, 1969, Gnathosyne Ponomarenko, 1969, Cephalosyne Ponomarenko, 1969, Petrosyne Ponomarenko, 1969, and Sphaerosyne Ponomarenko, 1969. This monophyletic unit is characterized by two synapomorphies of the prothorax, the absence of anterolateral pronotal angles and a rounded protruding anterior pronotal margin covering the posterior part of the head. Additional characters are large mandibles distinctly protruding anteriorly, striated elytra, an indistinct pronoto-elytral angle resulting in a stream-lined body, and a cuticular surface with coarse punctures. Based on the lack of the two prothoracic apomorphies, the Permian Archosyne Ponomarenko et al., 2014 is excluded from the family. As its placement remains very uncertain, it should be treated as Coleoptera incertae sedis. Ranis Ponomarenko, 1968 also lacks the pronotal features defining †Ademosynidae. Based on the internalized propleuron it is transferred to the megadiverse suborder Polyphaga. In its evolutionary history in the Mesozoic, †Ademosynidae reflects a general trend in Coleoptera, an increasing reinforcement of the configuration of the thoracic sclerites.