Ordovician acritarchs from the Canning Basin, Western Australia

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Abstract
Core samples from four marine Ordovician sections in the Canning Basin, Western Australia, have yielded an acritarch assemblage of moderate abundance and diversity and of varying preservation. The bulk of the palynologically productive samples represents the Goldwyer Formation and the remainder is from the conformably succeeding or laterally contiguous Nita Formation; these units have previously been regarded as datable within the late Arenigian to Llanvirnian (or ?Llandeilian) interval; i.e., late Early to Middle Ordovician. Newly instituted acritarch taxa comprise one new genus, Dasydorus, and 16 species, viz. Ammonidium aduncum, A. furtivum, A. macilentum, Baltisphaerosum pugiatum, B. variocavatum, Buedingiisphaeridium disgregum, Cymatiosphaera notialis, Dasydorus cirritus (type species), Elektoriskos pilulifera, Gorgonisphaeridium miculum, Lophosphaeridium aequicuspidatum, L. disparipelliculum, Micrhystridium goldwyerense, Multiplicisphaeridium acaciaense, Petaloferidium comptum, and Solisphaeridium cernuum. Among the other 13 species described are two of the palynoflora's major components that are newly combined with the genus Rhopaliophora Tappan & Loeblich 1971 (emended herein). The acritarch assemblage correlates with zones O4 and O5 of a previous chitinozoanacritarch study in the same region (Combaz & Peniguel, 1972), but exhibits little similarity in detail with age-equivalent assemblages from elsewhere.