Nektaspid arthropods from the lower Cambrian Emu Bay Shale Lagerstätte, South Australia, with a reassessment of lamellipedian relationships

Abstract

The lower Cambrian Emu Bay Shale on Kangaroo Island, South Australia, contains the only known Cambrian Burgess Shale-type biota in Australia. Two new lamellipedian arthropods, 'Emucaris fava' gen. et sp. nov. and Kangacaris zhangi gen. et sp. nov., from the Emu Bay Shale Lagerstätte are described as monotypic genera that are resolved cladistically as a monophyletic group that is sister to Naraoiidae + Liwiidae and classified within the Nektaspida as a new family Emucarididae. Shared derived characters of Emucarididae involve a bipartite, elongate hypostome and elongation of the pygidium relative to the cephalic shield and very short thorax. A monophyletic Liwiidae is composed of 'Liwia' and the Ordovician 'Tariccoia' + 'Soomaspis' but excludes 'Buenaspis', and even the membership of 'Buenaspis' in Nektaspida is contradicted amongst the shortest cladograms. New morphological interpretations favour affinities of 'Kwanyinaspis' with Conciliterga rather than with Aglaspidida, and 'Phytophilaspis' with Petalopleura.