Captopodus poschmanni gen. et sp. nov. a new stem-group arthropod from the Lower Devonian Hunsrück Slate (Germany)

A new arthropod from the Lower Devonian Hunsrück Slate is described on the basis of four specimens. The body of Captopodus poschmanni comprises a head, a trunk with an anal portion. The high number of trunk appendages (≥66 segments) is unusual. The function of one pair of cupola-like structures of the head shield is unclear. The presence of large grasping appendages in the head superficially resembles the ‘short great appendages’ of other euarthropods and grasping appendages of thylacocephalans. The phylogenetic position of the arthropod cannot be determined in detail, though several morphological aspects indicate a phylogenetic position as a stem lineage representative of the Euarthropoda, the morphology of the trunk appendages seem to indicate a more advanced phylogenetic position. This new taxon underlines the exceptional diversity of arthropods within the Hunsrück Slate in comparison to other Devonian fossil sites and highlights the significance of the Hunsrück Slate for the evolution of early arthropods.

► A new arthropod from the Lower Devonian Hunsrück Slate is described.
► The arthropod description contributes to the knowledge of arthropod diversity.
► The description of Captopodus poschmanni underlines the significance of the Hunsrück Lagerstätte.
► The presence of grasping appendages shows that a certain way of life in arthropods was widespread in the Palaeozoic.