Fossil dragonfly-type larva with lateral abdominal protrusions and implications on the early evolution of Pterygota

Summary

Aquatic larvae are known in three early branches of Pterygota: Ephemeroptera (mayflies), Plecoptera (stoneflies), and Odonata (dragonflies, damselflies). A common origin of these larvae has been suggested, yet also counterarguments have been put forward, for example, the different position of larval gills: laterally on the abdomen in Ephemeroptera, terminally in Odonata, variably in Plecoptera. We discuss recent fossil findings and report a new dragonfly-type larva from Kachin amber (Myanmar), which possesses ancestral characters such as a terminal filum, maintained in ephemeropterans, but lost in modern odonatan larvae. The new larva possesses lateral protrusions on the abdominal segments where in other lineages gills occur. Together with other fossils, such as a plecopteran retaining lateral gills on the abdomen, this indicates that lateral protrusions on the abdomen might have well been an ancestral feature, removing one important argument against the idea of an aquatic larva in the ground pattern of Pterygota.

Graphical abstract

Highlights

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  A new dragonfly-type larva was found in Kachin amber (Myanmar, 99 million years old).

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  The larva possesses a terminal filum, which is not known in modern dragonfly larvae

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  It also exhibits lateral abdominal protrusions where in other lineages gills occur

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  This find makes an aquatic larva in the ground pattern of Pterygota more likely

Abstract

Paleontology; Entomology; Evolutionary history; Paleobiology