A new aglaspidid-like euarthropod from the lower Cambrian Emu Bay Shale of South Australia

Abstract

A new euarthropod from the Emu Bay Shale (Cambrian Series 2, Stage 4) on Kangaroo Island, South Australia, is a rare component of this Konservat-Lagerstätte. The two known specimens of Eozetetes gemmelli gen. et sp. nov., in combination, depict a non-biomineralized euarthropod with a relatively short cephalic shield lacking dorsal eyes and bearing a flagelliform antenna, 18 trunk segments with broad tergopleurae and paired axial nodes/carinae, and an elongate, styliform tailspine. The new species compares most closely with taxa in the putative clade Vicissicaudata, which groups Aglaspidida, Cheloniellida and Xenopoda. A ring-like terminal tergite in E. gemmelli corresponds to the caudal tergite in cheloniellids and xenopodans. Incorporating Eozetetes into recent character sets for Cambrian euarthropods supports close affinities to either Emeraldella or to aglaspidids, but several plesiomorphic character states are inconsistent with membership in Aglaspidida sensu stricto. Eozetetes is among the earliest of various Cambrian taxa informally referred to as 'aglaspidid-like euarthropods'.