Sunday, March 26, 2017

[PaleoEntomology • 2017] Yijenplatycnemis huangi • Extreme Adaptations for Probable Visual Courtship Behaviour in A Cretaceous Dancing Damselfly

Yijenplatycnemis huangi
 Zheng, Nel, Jarzembowski, Chang, Zhang, Xia, Liu & Wang, 2017

Illustration by D. Zheng. DOI: 10.1038/srep44932 

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.

Figure 5: Reconstruction showing the courtship behaviour of Yijenplatycnemis huangi gen. et sp. nov. from the mid-Cretaceous tropical forest in Burma (drawn by Daran Zheng). 

Figure 1: Yijenplatycnemis huangi gen. et sp. nov.
Holotype (NIGP164757); photograph (A) and line drawing (B) of specimen (drawn by DZ). Paratype (BA16200); dorsal view (C) and anterior view (D) of specimen. 

Systematic palaeontology

Order Odonata Fabricius, 1793
Suborder Zygoptera Selys-Longchamps, 1854
Superfamily Coenagrionoidea Kirby, 1890

Family Platycnemididae Yakobson & Bianchi, 1905
Subfamily Palaeodisparoneurinae Poinar et al. 2011

Yijenplatycnemis huangi gen. et sp. nov

Etymology: The generic name is after Mr Huang Yijen, the donator of the type specimen, and the typical genus Platycnemis. The specific name is after Mr. Huang Yijen. Gender masculine.

Diagnosis: Very small damselfly, complete wing length about 11–14 mm; DC closed and quadrangular with MAb perpendicular to MAa; five postnodal and five postsubnodal crossveins present, somewhat aligned; only one postnodal crossvein present distal of Pt; midfork slightly basal of N; RP1 with strong angle below very long pterostigmal brace; area between RA and RP1 greatly widened distal of Pt; IR2 aligned with Sn; IR1 short, originating below Pt; MA long, ending on posterior wing margin below base of RP2; MP short, one or two cells long; CuA reduced to oblique vein; Pt very small, less than half length of surrounding cells; all tibiae spectacularly expanded, covered with two brown bands, in pod-like sclerite except on metatibiae where of semi-circular shape.


Daran Zheng, André Nel, Edmund A. Jarzembowski, Su-Chin Chang, Haichun Zhang, Fangyuan Xia, Haoying Liu & Bo Wang. 2017. Extreme Adaptations for Probable Visual Courtship Behaviour in A Cretaceous Dancing Damselfly.  Scientific Reports. 7, 44932. DOI: 10.1038/srep44932

Courtship behavior trapped in 100-million-year-old amber via @EurekAlert

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