A new cyclocystoid from the Lower Ordovician of Öland, Sweden

Monocycloides oelandicus gen. et sp. nov. is described from upper Arenig age beds on Öland, Sweden (Volkhov Stage, Langevoja Substage). The genus is monotypic and is the earliest known cyclocystoid echinoderm. Palaeogeographical origins of the cyclocystoids remain uncertain, but Monocycloides is regarded as a primitive sister group of the North American Ordovician Cyclocystoides.