Forever Love: The Hitherto Earliest Record of Copulating Insects from the Middle Jurassic of China

Shu Li,Chen Wang,Hong Pang,Dong Ren,Fabio S Nascimento,Chungkun Shih

doi:10.1371/journal.pone.0078188

Abstract

BackgroundMating behaviors have been widely studied for extant insects. However, cases of mating individuals are particularly rare in the fossil record of insects, and most of them involved preservation in amber while only in rare cases found in compression fossils. This considerably limits our knowledge of mating position and genitalia orientation during the Mesozoic, and hinders our understanding of the evolution of mating behaviors in this major component of modern ecosystems.Principal FindingHere we report a pair of copulating froghoppers, Anthoscytina perpetua sp. nov., referable to the Procercopidae, from the Middle Jurassic of northeastern China. They exhibit belly-to-belly mating position as preserved, with male's aedeagus inserting into the female's bursa copulatrix. Abdominal segments 8 to 9 of male are disarticulated suggesting these segments were twisted and flexed during mating. Due to potential taphonomic effect, we cannot rule out that they might have taken side-by-side position, as in extant froghoppers. Genitalia of male and female, based on paratypes, show symmetric structures.Conclusions/SignificanceOur findings, consistent with those of extant froghoppers, indicate froghoppers' genitalic symmetry and mating position have remained static for over 165 million years.

Highlights

Mating behaviors for extant insects have been studied and documented, for example, for froghoppers[1], scorpionflies[2] and planthoppers[3]
Boucot and Poinar[4] listed 33 instances of fossilized mating insects, such as fireflies, mosquitoes, planthoppers, leafhoppers, water striders, bees and ants, 27 of which are preserved in amber, others on compression fossils
We report a pair of well-preserved copulating froghoppers, Anthoscytina perpetua sp. nov., referable to the Procercopidae, from Jiulongshan Formation at the Daohugou Village in northeastern China

Summary

Introduction

Mating behaviors for extant insects have been studied and documented, for example, for froghoppers[1], scorpionflies[2] and planthoppers[3]. The nymphs of froghoppers are called spittlebugs because they cover themselves with foaming spittle, composed of tiny air bubbles trapped in secretions from their Malpighian tubules, which provides protection from predation, parasitism and desiccation[6] This discovery of the earliest record of copulating insects hitherto sheds light on the evolution of mating behavior in this group of insects. Cases of mating individuals are rare in the fossil record of insects, and most of them involved preservation in amber while only in rare cases found in compression fossils This considerably limits our knowledge of mating position and genitalia orientation during the Mesozoic, and hinders our understanding of the evolution of mating behaviors in this major component of modern ecosystems. Genitalia of male and female, based on paratypes, show symmetric structures

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