New dinoflagellate cyst species from the Middle Eocene of the Volgograd-Volga region, southwest Russia

AbstractThe Keresta Formation, located in the Volgograd-Volga region (the Volga-Caspian subregion of southwest Russia) has been dated as a Middle Eocene, Lutetian based on dinoflagellate cysts as the Enneadocysta arcuata Zone and nannofossils from the Lutetian Subzones CP13c-CP14a. Within this interval, four new species of dinoflagellate cysts were described: Spiniferella grigorovichiae sp. nov., Impagidinium tuberculatum sp. nov., Hystrichostrogylon crassitunicatum sp. nov. and Hystrichosphaeropsis tenerum sp. nov. The new species present a high correlation potential for Middle Eocene stratigraphy over the southern part of the Russian Platform. Also, the assemblage of organic-walled microphytoplankton from the Keresta Formation indicates warm water marine environments within the marginal part of the Paratethys Basin.Keywords: Dinoflagellate cystsMiddle EoceneLutetiansouthwest RussiaVolgograd-Volga regionDisclaimerAs a service to authors and researchers we are providing this version of an accepted manuscript (AM). Copyediting, typesetting, and review of the resulting proofs will be undertaken on this manuscript before final publication of the Version of Record (VoR). During production and pre-press, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal relate to these versions also.