Subfamily Palaeoxeninae from the Middle Jurassic Jiulongshan Formation of China (Coleoptera, Eucnemidae)

The eucnemid Palaeoxenus clavatus sp. nov. is described from the Middle Jurassic Jiulongshan Formation of Inner Mongolia, China. This is the second record of eucnemids from the Jiulongshan Formation and the first record of the subfamily Palaeoxeninae Muona from the Jurassic. This discovery confirms that all basal lignicolous Eucnemidae subfamilies, Schizophilinae, Pseudomeninae, Anischiinae and Palaeoxeninae, had evolved in the Jurassic before the angiosperm radiation. Palaeoxeninae being the sister-group of the clade (Melasinae, Eucneminae, Macraulacinae), the “Derived Eucnemidae”, DE for short, this new record proves that the DE clade originated in the Jurassic as well. On the basis of fossil evidence, the modern Eucnemidae diversity appears to be connected with the angiosperm radiation in Upper Cretaceous to Paleocene. However, this diversification was facilitated by the larval special adaptations for extraoral feeding inside gymnosperm wood, a feature already present in the Jurassic.Peer reviewe