Saturday 28 December 2013

Leaf mimicry in a Jurassic Scorpionfly.

The Scorpionflies (Mecoptera) are a group of insects related to the True Flies. They get their name from the reproductive organs of the males of some species, which resemble the tails of Scorpions. Despite this fierce appearance most species are harmless herbivores, though it is thought that fleas are highly specialised members of the group, and the True Flies, Butterflies and Moths may have evolved from the group in the Mesozoic. The group has a fossil record dating back to the Permian, and it has been suggested that the Scorpionflies were the first Insects to pollinate plants, possibly pollinating gymnospermous plants in the Jurassic before the origin of true flowering plants.

In a paper published in the Proceedings  of the National Academy of Sciences of the United States of America on 26 November 2012, a team of scientists led by Yongjie Wang of the College of Life Sciences at Capital Normal University in Beijing describe a new species of Scorpionfly from the Middle Jurassic Jiulongshan Formation from Daohugou Village in Inner Mongolia, which they suggest may have been camouflaged to resemble the leaves of a Ginkgoalean Plant uppon which the Insect lived.

The new species is named Juracimbrophlebia ginkgofolia, where 'Juracimbrophlebia' means 'Jurassic Cimbrophlebia' (a modern genus of Scorpionfly to which Juracimbrophlebia is thought to be related) and 'ginkgofolia' means 'Ginko-leaf'. Juracimbrophlebia ginkgofolia is a ~38.5 mm Hangingfly (long-legged Scorpionfly superficially resembling a Cranefly).

Specimens of Juracimbrophlebia ginkgofolia from the Middle Jurassic Jiulongshan Formation of Inner Mongolia. Scale bars are 10 mm. Wang et al. (2012).

The specimens were found alongside preserved leaves of the Ginkgo Yimaia capituliformis, with the Insect and Plant fossils proving confusing to separate, both in the field and the lab. Wang et al. suggest that this is a result of mimicry on behalf of the Scorpionfly, which would have been camouflaged among the leaves of the Ginkgo in life.

Leaves of Yimaia capituliformis  from the Middle Jurassic Jiulongshan Formation of Inner Mongolia. Scale bars are 10 mm. Wang et al. (2012).

 Wings of Juracimbrophlebia ginkgofolia (H&I) and leaves of Yimaia capituliformis (J&K), illustrating the similarities. Scale bars are 10 mm. Wang et al. (2012).

Reconstruction of Juracimbrophlebia ginkgofolia in life. Wang et al. (2012).

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