Stratigraphic and geographic distribution of Eocene-Miocene Radiolaria from the Southwest Pacific

The known stratigraphic and geographic ranges of 50 recently erected species and five recently erected genera of Radiolaria, originally described from the New Zealand area (from the Mahurangi Limestone and Puriri Formation in Northland, and the Oamaru Diatomite in the South Island), are documented. The data is significantly updated from that presented in the original descriptions, and includes information from several DSDP/ODP localities that were not investigated in the original studies. All taxa considered as belonging in the recently erected genera are listed, and full synonymies cover all forms considered as belonging to the recently erected taxa. During the reinvestigation of samples from DSDP Hole 280A three new species were noted and are described herein. The new species are Dictyoprora nigriniae, Plannapus? aitai (Artostrobiiadae), and Lithomelissa? sakaii (Plagoniidae). Problems with some age indicator taxa are discussed, namely the possible diachroneity of the last occurrence of Lychnocanium amphitrite, and the extent of the age overlap between Stichocorys delmontensis and Calocycletta (Calocyclopsis) serrata. A distinct biogeographic boundary to Radiolaria exists between the Mahurangi Limestone (Latest Eocene to earliest Miocene), and the Late Eocene to Oligocene sections of the other South Pacific localities investigated. This necessitated the use of two different radiolarian zonal schemes for establishing the age ranges of the new taxa. The boundary seems to be attributable to differing latitudes of deposition and associated water circulation patterns.