New early Eocene Siricomorpha (Hymenoptera: Symphyta: Pamphiliidae, Siricidae, Cephidae) from the Okanagan Highlands, western North America

Abstract

We describe three new genera and four new species (three named) of siricomorph sawflies (Hymenoptera: Symphyta) from the Ypresian (early Eocene) Okanagan Highlands: Pamphiliidae,Ulteramus republicensisnew genus, new speciesfrom Republic, Washington, United States of America; Siricidae,Ypresiosirex orthosemosnew genus, new speciesfrom McAbee, British Columbia, Canada; and Cephidae,Cuspilongus cachecreekensisnew genus, new speciesfrom McAbee and another cephid treated as Cephinae species A from Horsefly River, British Columbia, Canada. These are the only currently established occurrences of any siricomorph family in the Ypresian. We treat the undescribed new siricoid from the Cretaceous Crato Formation of Brazil as belonging to the Pseudosiricidae, not Siricidae, and agree with various authors that the YpresianMegapterites mirabilisCockerell is an ant (Hymenoptera: Formicidae). The Miocene speciesCephites oeningensisHeer andC. fragilisHeer, assigned to the Cephidae over a century and a half ago, are also ants. Many of the host plants that siricomporphs feed upon today first appeared in the Eocene, a number of these in the Okanagan Highlands in particular. The Okanagan Highlands sites where these wasps were found also had upper microthermal mean annual temperatures as are overwhelmingly preferred by most modern siricomorphs, but were uncommon in the globally warm Ypresian, only found then in higher elevations and highest latitudes.

Mitogenome organization and evolutionary history of the subfamily Cephinae (Hymenoptera: Cephidae)

“…A recent study on the phylogeography of C. cinctus has also revealed haplogroup structuring due to host plant preference, implying a selective regime necessary to adapt to novel hosts (Lesieur et al ., ). It is interesting to note that fossil records from the Early Cretaceous and Late Eocene (Archibald & Rasnitsyn, ) also correspond to major diversification periods of Cephinae.…”

“…Cephid fossil records are known from the Early Cretaceous ( Mesocephus sibiricus Rasnitsyn) to Late Eocene ( Janus disperditus Cockerell and Electrocephalus stalendorffi Konow) (summarized by Taeger et al ., ). All Eocene records are assigned to the subfamily Cephinae, including a recent record of Cuspilongus cachecreekensis Archibald and Rasnitsyn (Archibald & Rasnitsyn, ). However, the age of cephids is estimated to be much older (Ronquist et al ., ).…”

“…However, the age of cephids is estimated to be much older (Ronquist et al ., ). Considering fossil records of Cephinae together with the rich fossil record of its likely woody host plants during the Eocene suggests a more complex history of host plant interactions (Archibald & Rasnitsyn, ) than that recently indicated (Budak et al ., ). The significant role of host shifts in speciation has been understood in recent years and investigation of the adaptive processes of phytophagous insects to their host plants has led to the development of a general hypothesis known as ecological speciation (Rundle & Nosil, ; Matsubayashi et al ., ; Forbes et al ., ).…”

Modernisation of the Hymenoptera: ants, bees, wasps, and sawflies of the early Eocene Okanagan Highlands of western North America

“…Insects share numerous closely related taxa between northern continents in the Eocene (Archibald 2005, 2009; Archibald et al . 2005, 2006, 2011b; Archibald and Makarkin 2006; Petrulevičius et al . 2007; Makarkin and Archibald 2013; Dlussky et al .…”

“…Only the coeval Tadushi Formation of Pacific coastal Russia might also represent an Ypresian insect assemblage preserved in such a cooler upland (Archibald et al . 2005; age of the Tadushi: Popov and Grebennikov 2001), although some others may have had a mixture of source communities possibly including such an environment ( e.g ., the Fur Formation: Archibald and Makarkin 2006). The Tadushi, however, contains fewer and less diverse Hymenoptera than the Okanagan Highlands despite large collections, a fact that cannot easily be explained as a taphonomic artefact, and may then represent a community with a genuinely smaller component of the order.…”