Extreme adaptations for probable visual courtship behaviour in a Cretaceous dancing damselfly

Daran Zheng,Haichun Zhang,Fangyuan Xia,André Nel,Su-Chin Chang,Edmund A Jarzembowski,Haoying Liu,Bo Wang

doi:10.1038/srep44932

Abstract

Courtship behaviours, frequent among modern insects, have left extremely rare fossil traces. None are known previously for fossil odonatans. Fossil traces of such behaviours are better known among the vertebrates, e.g. the hypertelic antlers of the Pleistocene giant deer Megaloceros giganteus. Here we describe spectacular extremely expanded, pod-like tibiae in males of a platycnemidid damselfly from mid-Cretaceous Burmese amber. Such structures in modern damselflies, help to fend off other suitors as well as attract mating females, increasing the chances of successful mating. Modern Platycnemidinae and Chlorocyphidae convergently acquired similar but less developed structures. The new findings provide suggestive evidence of damselfly courtship behaviour as far back as the mid-Cretaceous. These data show an unexpected morphological disparity in dancing damselfly leg structure, and shed new light on mechanisms of sexual selection involving intra- and intersex reproductive competition during the Cretaceous.

Highlights

Courtship behaviour is quite frequent among in extant insects[1,2]
Direct evidence of courtship behaviour in fossils is extremely rare: male mecopterans have exaggerated body parts used for sexual display[14] and the male Karataus Rasnitsyn[15] (Middle Jurassic, Hymenoptera) has swollen hind femora used for courtship display or to assist attachment to the female[15,16]
We describe a new damselfly with expanded tibiae uniquely probably used for courtship from mid-Cretaceous Burmese amber

Summary

Introduction

Courtship behaviour is quite frequent among in extant insects[1,2]. In odonates, the male must persuade the female to mate in tandem and the female should be willing to engage her genitalia with the male’s3. Most courtship, mating and parenting (social-sexual) behaviour cannot be preserved and fossil reports are few and ambiguous[7]. Some cases of insect mating behaviour are better preserved in amber compared with rare records in sedimentary rocks[8,9,10]. Direct evidence of courtship behaviour in fossils is extremely rare: male mecopterans have exaggerated body parts used for sexual display[14] and the male Karataus Rasnitsyn[15] (Middle Jurassic, Hymenoptera) has swollen hind femora used for courtship display or to assist attachment to the female[15,16]. We describe a new damselfly with expanded tibiae uniquely probably used for courtship from mid-Cretaceous Burmese amber. The new find reveals ancient courtship, insect interaction and sexual selection from as far back as the mid-Cretaceous

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Conclusion