Fossil weaver ants (Hymenoptera, Formicidae, Oecophyllini) of the early Eocene Okanagan Highlands of far-western North America

Abstract

Abstract We examine the fossil weaver ants (Formicidae, Formicine, Oecophyllini) of the early Eocene Okanagan Highlands fossil localities of British Columbia, Canada and Washington, United States of America, naming Eoecophylla quilchenensisn. gen. et sp. from Quilchena (British Columbia), formally transferring Camponotites kraussei Dlussky and Rasnitsyn (Republic, Washington) to the genus Oecophylla Smith, F., and describing but not naming a worker (McAbee, British Columbia), treated as Oecophyllinisp. A. These are the oldest known Oecophyllini (Oecophylla + Eoecophylla) and Oecophylla. Forewing vein stubs of E. quilchenensis and its well-developed hind wing vein M are plesiomorphies; this M is unique within the subfamily, suggesting Oecophyllini is sister to other Formicine. The head shape of O. kraussein. comb. indicates a close relationship to Oecophylla longiceps Dlussky from Eocene Messel, Germany. The ant Titanomyrma Archibald et al. is also known from the Okanagan Highlands and Messel, consistent with Late Cretaceous/early Paleogene intercontinental dispersal. We discuss possible host plants and trophobionts of these ants. Although Okanagan Highlands localities were cooler than the Paleotropical range of modern Oecophylla, their presence there might be explained by mild winters without significant frost.