Caught in the Act – 165 Million Years Later.

As scientists continue to gain a better understanding of the fossil record, an increasingly complete picture of ancient life is being formed. Although the world looked very different millions of years ago, it’s interesting to note that some organisms have remained rather similar despite sensational changes within their environments. One group of organisms that has remained successful throughout millions of years is the insects.

Although insect palaeontologists have a confident idea of what insect diversity was like millions of years ago, it is truly difficult to discern behaviour from fossil specimens. This is why a 165-myo fossil of mating froghoppers found in the Jiulongshan Formation in north-eastern China has garnered significant attention. Li et al. (2013) have recently published a detailed record of the fossilized anatomy of a copulating pair.  The team is unsure if the fossil indicates a ‘front-to-front’ or ‘side-by-side’ mating position. If the species were indeed ‘side-by-side’, they would be mating in the same way that froghoppers do today. The evidence seems to suggest that the pair mated from either side of a grass blade or stem to allow copulation in a ‘front-to-front’ position, although this could be an effect of taphonomy.

The detail in the fossil shows a clear depiction of  the male reproductive organ (the aedeagus) inserting into the female copulatory structure (bursa copulatrix). Despite the potential differences in reproductive behaviour, the anatomy of the genitalia is incredibly similar to extant species. This 135-myo male even has the same number of segments in the aedeagus! This suggests that besides a possible change in position, froghopper sex has remained the same for the last 165-odd million years.

Photographs of the froghopper fossils with accompanying diagrams. Scale bars = 1 mm. From Li et al., 2013; doi:10.1371/journal.pone.0078188.g001

If you’re not familiar with these lovely creatures, froghoppers (Hemiptera: Cercopoidea) are a diverse superfamily of insects that use their straw-like mouthparts to suck nutrients from plant tissue. If you’ve spent any amount of time outdoors, chances are you’ve been in contact with these curious insects. The adults are small, quick, and often exhibit striking, aposematic colouration. The juveniles conceal themselves by secreting a foaming mass of plant sap and air bubbles. This structure serves as protection from predation and desiccation. Due to this defensive behaviour, froghoppers are also commonly known as ‘spittlebugs’. Several species of froghoppers are economically significant agricultural pests.

Froghopper nymph adjacent to protective spittle mass (Photo by Yerpo: Wikimedia Commons)

The authors described this particular species, giving it the name ‘Anthoscytina perpetua‘. The species name draws from the Latin word perpet meaning ‘eternal love‘. Certainly an appropriate choice for a pair engaged in such a paleontological-coitus-marathon! This fascinating discovery represents the earliest record of copulating insects found to date. It suggests that the anatomy of froghopper genitalia has remained static since brachiosaurs roamed the lands, although it would appear that they’ve since changed sex positions at least once. As they say, variety is the spice of life!

References:
Li, S., Shih, C., Wang, C., Pang, H. & Ren, D (2013) Forever Love: The Hitherto Earliest Record of Copulating Insects from the Middle Jurassic of China. PLoS ONE 8, e78188.