A new interpretation of the enigmatic fossil arthropod Anhelkocephalon handlirschi Bill, 1914 – important insights in the morphology of Cyclida

Anhelkocephalon handlirschiBill, 1914 has been described as a representative of Isopoda (woodlice and relatives). Fossils of A. handlirschi come from the Grès à Voltzia Formation in western France, close to the German border. The Grès à Voltzia Formation (Voltziensandstein) is Triassic in age; lithostratigraphically, it belongs to the Buntsandstein Group. Based on the morphology of the type material and one additional specimen, we interpret A. handlirschi not as a representative of Isopoda, but as a representative of Cyclida. Cyclida is an extinct group of Euarthropoda, the representatives of which have a circular to oval outline of the body (in dorsal view). One of the herein studied specimens has aspects of appendage morphology preserved, which, in general, is a rare case for cyclidans. The herein studied specimens also add new features to the knowledge about the morphology of Cyclida, such as a net-like pattern on the dorsal body side.