Abstract
Eutomostethus karimae sp. nov., the first fossil representative of the sawfly subfamily Blennocampinae, is described from the Eocene Green River Formation (Colorado, USA). Extant representatives of the genus Eutomostethus are distributed in the Palaearctic and the Oriental regions, with two species probably introduced by humans in the Nearctic Region. The presence of a fossil related to this genus in the Eocene of North America is in accordance with the different land bridges present at that time and allowing important entomofaunal exchanges between this region and Eurasia. The present discovery also corroborates the recent estimate of the divergence of the subfamily Blennocampinae at the extreme end of the Cretaceous.
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