Cambrian palaeoscolecids (Cycloneuralia) from Gondwana and reappraisal of species assigned to 'Palaeoscolex'

Abstract

The discovery of new palaeoscolecid material (Cycloneuralia) from the Emu Bay Shale Konservat-Lagerstätte of Kangaroo Island, South Australia (Cambrian Series 2, Stage 4) and from the Murero biota of NE Spain (Cambrian Series 3, Stage 5-Drumian) has prompted a reappraisal of 'Palaeoscolex' Whittard, 1953, the genus to which species from these, and other Cambrian localities, have most recently been assigned. Available data from scanning electron microscopy show the presence of 'Hadimopanella'-type sclerites covering the surface of these taxa, permitting taxonomic schemes based on microfossils and whole-body compression fossils to be reconciled. The sclerite pattern, size and shape indicate that several of the Cambrian species assigned to 'Palaeoscolex' need to be reassigned to 'Wronascolex' Ivantsov and Zhuravlev, 2005, a genus originally described from Siberia. The studied material includes 'Wronascolex antiquus' ( Glaessner, 1979) and 'Wronascolex iacoborum sp'. nov. from Kangaroo Island (Australia) and two new specimens of 'Wronascolex'? from the Iberian Ranges (Spain). SEM examination of the types of 'Palaeoscolex ratcliffei' Robison, 1969, a Cambrian species from Utah to which Murero material has been compared, suggests that this species should possibly be assigned to 'Wronascolex'. These taxa are also considered in a Cambrian palaeobiogeographic context, together with the presence of isolated Hadimopanella sclerites, showing a distribution of Wronascolex largely confined to palaeotropical environments.