An endoparasitoid Cretaceous fly (Diptera: Eremochaetidae) and the evolution of parasitoidism

Publication Type:Conference Paper
Year of Publication:2016
Authors:Zhang, Q, Zhang, J, WANG, BO
Conference Name:The 7th International Conference on Fossil Insects, Arthropods and Amber
Date Published:26/04/2016
Publisher:Siri Scientific Press
Conference Location:National Museum of Scotland, Edinburgh

Eremochaetidae (Diptera: Brachycera) is an important, but relatively small, extinct group ranging from the Late Jurassic to Early Cretaceous. So far, only eight genera with 16 species have been recorded from China, Kazakhstan, Russia and Mongolia. Here, we report on a new genus and species from Late Cretaceous Burmese amber (~99 Ma), which represents the latest occurrence of the family.The family Eremochaetidae possesses a special combination of characters: the crossvein r-m is absent, vein R4+5 (sometimes veins R2+3 and R4+5) arising from cell d, ovipositor aculeate terminally. The new species possesses large eyes occupying almost entire head, extensively holoptic in the female; ocellar tubercles well developed, fringed with setulae; antennae obviously thin and short; ocelli well developed; mesonotum compact; scutellum very short; Rs originating from R stem distal to level of M fork; cell r1 closed, with short or absent petiole; R4+5+M1 separating from anterior margin of d; discal cell hexagonal; cell cu closed with short petiole; claws and empodium extremely elongated, formed tridactylous claws; tibial spurs absent; tarsi very short; claws and empodium extremely elongated; female ovipositor subulate, aculeate terminally. The specialised needle-like ovipositor in these flies is used for injecting its eggs into hosts. The specialised characteristics of this bizarre fly can be interpreted as follows: Enlarged tridactylous claws were used for clasping their hosts, whereas the strongly reduced antennae and markedly convex large eyes suggest these flies relied on visual cues for locating and selecting their hosts. Also, given their needle-like ovipositor, these flies appear to have evolved an endoparasitoid lifestyle by the Middle Jurassic.

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