ABSTRACT: Rich calcareous nannoplankton assemblages were ecovered from the Badenian (Middle Miocene) in Slovenske gorice (Eastern Slovenia). Paleogeographically, the investigated area belonged to the Mura Depression, a heterogenous marginal basin of the Central Paratethys. Over one hundred species of calcareous nannoplankton were found in the Badenian marls, among them two new Pontosphaera species were determined and are described in this paper. The nannoplankton assemblages, containing specimens of Pontosphaera geminipora n. sp. and Pontosphaera desuetoidea n. sp., allow their assignment to the standard nannoplankton biozone NN5. Both species are rare and occur in diverse assemblages, indicating warm and stable, relatively deep and oligotrophic depositional environments.