Claws reinvented

"Previously, such chelae were known from only three insect groups. This fossil therefore represents the fourth known case of these structures evolving independently in insects," explains Privatdozentin Carolin Haug, zoologist at LMU's Faculty of Biology.

Working with her team and in collaboration with researchers from the University of Rostock and the University of Oulu in Finland, Haug used micro-computed tomography to examine the fossil and visualize all structures of its anatomy in 3D.

A quantitative morphological analysis of the shapes of more than 2,000 chelae and similar grasping structures from various extinct and living species showed that the chelae of the fossil true bug differ markedly from the corresponding structures in other insect species. In fact, similarly structured chelae occur in somewhat more distantly related arthropods such as decapods (crabs, lobsters, shrimps, etc.) and tanaids.

Water bugs in K-pop pose

Because of this distinctive feature, the researchers placed the fossil in a new genus of its own and gave it the scientific name Carcinonepa libererrantes. The genus name combines the Latinized Greek word for "crab" (carcino-) with nepa, a reference to the group of true water bugs known as Nepomorpha.