New occurrence of the Burgess Shale arthropod Sidneyia in the Early Cambrian Chengjiang Lagerstätte (South China), and revision of the arthropod Urokodia

A single specimen of Sidneyia Walcott, 1911, from the Early Cambrian Chengjiang Lagerstätte in the Maotianshan section, Yunnan Province, is the first occurrence of the genus outside Laurentia. The specimen shows the basic characteristics of Sidneyia: the body is composed of a cephalon with long (sag.) doublure, a thorax of nine articulating somites, an abdomen of two or three somites and a telson with lateral flaps. The cephalon, however, is semi-elliptical in dorsal view and the telson elongate, differing from the rectangular cephalon and the triangular telson of the type species Sidneyia inexpectans. Accordingly, a new species, Sidneyia sinica, is erected. In addition, a near-complete specimen of Urokodia aequalis from the Chengjiang fauna, in the Haoyicun section, Yunnan Province, provides new information on the trunk and tail shield morphology, necessitating a revision of its diagnosis.