Diversity and morphology of Eocene and Oligocene Mordellidae (Coleoptera)

Characteristics of the locomotor apparatus (excluding wings) and other diagnostic features of Mordellidae preserved in Eocene Baltic and Rovno amber are investigated. Main features of Eocene Mordellidae are compared with those of their extant relatives using mainly light microscopy and micro-CT scans. The entire record of Eocene and Oligocene fossils of this family is reviewed, revealing a great number of discrepancies in diagnoses of species of Eocene and Oligocene Mordellidae at the generic level, which makes a reliable discussion of their biogeography and relationship with extant species impossible. To overcome this situation, four new collective group names (i.e., without a type species designation) are established: Baltimorda nov., Baltistena nov., Rovnostena nov., and Petrimordella nov. Seven new species of Mordellistenini from Baltic amber are described, diagnosed and illustrated: Baltistena ultima sp. nov., B. aurata sp. nov., B. longistrigata sp. nov., B. hoffeinsorum sp. nov., B. concava sp. nov., B. brevispina sp. nov., and B. atronigra sp. nov. The number of Mordellistenini recorded from Baltic amber is doubled from seven to fourteen. The subgenus Palaeostena Kubisz, 2003, with the type species Falsomordellistena eocenica Kubisz, 2003, is elevated to a genus.