Systematic revision of the oryctocephalid trilobite Protoryctocephalus arcticus Geyer & Peel, 2011 from the lower Cambrian (Stage 4) of Balang, South China

The oryctocephalid trilobites from the traditional 'lower-middle Cambrian' represent key tools for international correlation. The trilobite zones in South China around the Cambrian Series 2-Miaolingian are made using orycto-cephalids. One of the trilobite zones suggested is based on Prototyctocephalus arcticus. Prototyctocephalus from the Balang area in South China was described as Protoryctocephalus wuxunensis, also from the Cambrian Series 2 of South China. However, Prototyctocephalus from Balang shows different morphological features such as different glabellar shape, presence of a transglabellar 51 and more segments in the trunk. These features match with Protoryctocephalus arcticus from the Cambrian Series 2 of Greenland.