Monday 27 May 2013

An early Woodwasp from the Early Cretaceous of Brazil.

The Hymenoptera are one of the largest groups of insects, comprising Sawflies, Wasps, Ants and Bees. The earliest members of the group were Sawflies, which appeared around the beginning of the Late Triassic. Sawflies have caterpillar-like larvae that consume plant material, gaining their name from their saw-like ovipositor (egg-laying organ), which is adapted to cutting into plants, where eggs are laid. Woodwasps are considered to be the oldest group of Wasps, descended from Sawflies and ancestral to all other Wasps, and therefore Ants and Bees. They have a needle-like ovipositor, that is used to inject eggs into either a plant or animal host. Wasps, and later Ants and Bees, underwent dramatic evolutionary radiations during the Cretaceous, coinciding with the rise of the flowering plants.

In a paper published in the journal Systematic Entomology on 8 November 2011, Lars Krogmann of the Staatliches Museum für Naturkunde in Stuttgart and  and André Nel of the Muséum National d’Histoire Naturelle in Paris describe a new species of Woodwasp from the Lower Cretaceous Crato Formation of northeastern Brazil.

The new species is named Cratoenigma articulata, where Cratoenigma means 'enigma from Crato' and articulata refers to an artculation on the upper surface of the thorax. Cratoenigma articulata is an 11 mm Insect preserved in limestone. It is clearly a Woodwasp, but does not appear to belong to any known group of Woodwasps, having a mixture of features from a variety of groups. Krogmann and Nel suggest that this may imply that Cratoenigma articulata is the sister group to all other Woodwasps, and therefore all other Wasps, Ants and Bees.

Cratoenigma articulata. Scale bar is 2 mm. 

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