Extreme adaptations for aquatic ectoparasitism in a Jurassic fly larva

The reconstruction of ancient insect ectoparasitism is challenging, mostly because of the extreme scarcity of fossils with obvious ectoparasitic features such as sucking-piercing mouthparts and specialized attachment organs. Here we describe a bizarre fly larva (Diptera), Qiyia jurassica gen. et sp. nov., from the Jurassic of China, that represents a stem group of the tabanomorph family Athericidae. Q. jurassica exhibits adaptations to an aquatic habitat. More importantly, it preserves an unusual combination of features including a thoracic sucker with six radial ridges, unique in insects, piercing-sucking mouthparts for fluid feeding, and crocheted ventral prolegs with upward directed bristles for anchoring and movement while submerged. We demonstrate that Q. jurassica was an aquatic ectoparasitic insect, probably feeding on the blood of salamanders. The finding reveals an extreme morphological specialization of fly larvae, and broadens our understanding of the diversity of ectoparasitism in Mesozoic insects.The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication. This paper was supported by the following grant(s): Alexander von Humboldt Foundation CHN 1149090 STP to Bo Wang. National Basic Research Program of China 2012CB821900 to Jun Chen. National Natural Science Foundation of China (NSFC) FundRef identification ID: http://dx.doi.org/10.13039/501100001809 41272013, 41372014, J1210006 to Jun Chen. Natural Scientific Foundation of Shandong Province ZR2013DQ017 to Jun Chen. National Science Foundation (NSF) FundRef identification ID: http://dx.doi.org/10.13039/100000001 DEB-0542909 to Michael S Engel. Chinese Academy of Sciences (CAS) FundRef identification ID: http://dx.doi.org/10.13039/501100002367 CAS 2011T2Z04 to Edmund A Jarzembowski