A new species of the artiopodan arthropod Acanthomeridion from the lower Cambrian Chengjiang Lagerstätte, China, and the phylogenetic significance of the genus

New material of the rare arthropod Acanthomeridion, including Acanthomeridion anacanthus sp. nov., is described from the lower Cambrian Chengjiang biota, Yunnan Province, China. The material includes a specimen with paired gut diverticulae along the length of the mid-gut that resemble structures in other artiopodan arthropods such as naraoiids. Previous phylogenetic analyses have indicated a petalopleuran/xandarellid affinity for Acanthomeridion, but our analysis resolves Acanthomeridion outside the main subclades of the Artiopoda (Aglaspidida + Trilobita, Nektaspida, Cheloniellida + Xenopoda, Conciliterga, Petalopleura (including Xandarellida)) as the most basal artiopodan.