The Eocene apex of panorpoid scorpionfly family diversity

Abstract

The scorpionfly (Mecoptera) superfamily Panorpoidea underwent an Eocene radiation, replacing the extinct Mesozoic orthophlebiid grade and reaching its greatest family-level diversity: Panorpidae, Panorpodidae, Austropanorpidae, Holcorpidae, Dinopanorpidae, and a new family proposed here, the Eorpidae. Only the Panorpidae and Panorpodidae survived the Eocene and persist to the present day. This cluster of family extinctions is exceptional within Cenozoic insects. The Eorpidae includes at least one new genus and three new species described here from four localities of the early Eocene Okanagan Highlands of British Columbia, Canada, and Washington, U.S.A.:Eorpa ypsipedan. gen. n. sp. (McAbee and possibly Falkland, BC, Canada; and Republic, WA, U.S.A.),Eorpa elverumin. gen. n. sp. (Republic), andEorpa jurgenin. gen. n. sp. (Quilchena, BC). Some of the other fragmentary and poorly preserved specimens might represent further new species. We propose that the apex of Panorpoid family diversity ended by pressures from post-Eocene icehouse world climatic stress and the rise to ecological dominance of ants, some of which would have provided strong competition in scavenging for dead arthropods.