The Middle Ordovician Proventocitum procerulum radiolarian assemblage of Spitsbergen and its biostratigraphic correlation

The Proventocitum procerulum radiolarian assemblage from the Valhallfonna Formation of Spitsbergen is described for the first time in some detail from material investigated in transmitted light. A number of species are recognized in the well-preserved material, showing unexpected diversity. The age of the fauna is restricted to the early Darriwilian (Da1-2), based on comparison with precisely dated radiolarian assemblages from the Cow Head and Table Head Groups of western Newfoundland. Most species, however, are left in open nomenclature until additional material is available for SEM investigation. Inanigutta magnifica n. sp. is described as new.