Palaeoscolecidan worms and a possible nematode from the Early Ordovician of South China

Several species of palaeoscolecidan worm have been found in the Tonggao Formation (earliest Floian) of Guizhou Province, China. Two new palaeoscolecidan taxa are described (Sanduscolex regularis n. gen. n. sp. and Ashetscolex nuppus n. gen. n. sp.); another palaeoscolecidan (Wronascolex sp.) is left in open nomenclature. This is the youngest known occurrence of Wronascolex. A possible large free-living nematode is described and illustrated, representing the earliest known nematode in the fossil record, and a rare example from a marine setting.