Abstract
Parasitoid wasps of the family Ichneumonidae are one of the most diverse and species-rich groups of organisms with a worldwide distribution. We here describe seven new ichneumonid fossil species and two new genera from a remarkable insect fossil site, the Eocene Messel Pit in Germany (~47Ma). The unique fossil preservation allows us to place five out of the seven new species unequivocally in extant subfamilies and genera. For the first time, lobed claws which are a clear synapomorphy for the subfamily Pimplinae, are observed in a fossil, making the newly described Scambus fossilobus sp. nov. the oldest unequivocal representative of the group. We also describe a fossil of Labeninae (Trigonator macrocheirus gen. et sp. nov.), an ichneumonid subfamily that was until now believed to be an exclusively Gondwanan element. Furthermore, the newly described Rhyssella vera sp. nov., Xanthopimpla messelensis sp. nov., and X. praeclara sp. nov. provide evidence that these extant genera date back as far as the Early/Middle Eocene. In contrast to the clear placement of most of the newly described species, we were unable to place Polyhelictes bipolarus gen. et sp. nov. and Mesornatus markovici gen. et sp. nov. in an ichneumonid subfamily, mostly due to the high levels of homoplasy found in this group. These findings on the one hand demonstrate the need for a more rigorous approach in the taxonomic placement of fossil ichneumonids, and on the other hand provide more precise minimum ages for several ichneumonid genera and subfamilies.
Highlights
The parasitoid wasp family Ichneumonidae is one of the largest groups of organisms, with more than 24,000 species described up to date [1] and at least 60,000 estimated [2,3]
The oldest fossils of Ichneumonidae date back to the Early Cretaceous. These include representatives of the extinct subfamilies Palaeoichneumoninae Kopylov and Tanychorinae Rasnitsyn [5,8,9,10]. These two subfamilies are replaced in the fossil record of the Late Cretaceous by the recently described Novichneumoninae Li et al [11] and by the morphologically rather heterogeneous subfamily Labenopimplinae Kopylov, which was suggested as a potential ancestor of the extant subfamily Labeninae Ashmead or, less likely, Pimplinae Wesmael [12]
The only known Cretaceous fossil that is currently placed in an extant subfamily, Albertocryptus dossenus McKellar et al [13] from Canadian amber, is considered to be a labenine
Summary
The parasitoid wasp family Ichneumonidae is one of the largest groups of organisms, with more than 24,000 species described up to date [1] and at least 60,000 estimated [2,3]. The oldest fossils of Ichneumonidae date back to the Early Cretaceous These include representatives of the extinct subfamilies Palaeoichneumoninae Kopylov and Tanychorinae Rasnitsyn (the placement of the latter within the family is controversial) [5,8,9,10]. These two subfamilies are replaced in the fossil record of the Late Cretaceous by the recently described Novichneumoninae Li et al [11] and by the morphologically rather heterogeneous subfamily Labenopimplinae Kopylov, which was suggested as a potential ancestor of the extant subfamily Labeninae Ashmead or, less likely, Pimplinae Wesmael [12]. This fossil is clearly an ichneumonid, but its placement within the subfamily Labeninae is questionable according to the authors of the original description [13]
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