Alveolinids at the Middle-Upper Eocene boundary in northeastern Italy (Veneto, Colli Berici, Vicenza)

The Middle and Upper Eocene successions of the Colli Berici (Veneto, northeastern Italy) have been studied since the beginning of the nineteenth century in order to describe the large, benthic foraminiferal-rich assemblages. The Bartonian-Priabonian exposures in the southeastern part of the Colli Berici (Mossano) have been the proposed "parastratotype" for the Priabonian stage. The classic Mossano section and two additional sections outcropping in this area, all spanning the Calcari Nummulitici (Middle Eocene)-Marne di Priabona (Late Eocene) formations, provided us with new biostratigraphic data about two alveolinid species. Borelis vonderschmitti (Schweighauser) has so far been recorded in the Colli Berici (type locality Cava Zengele) within the Bartonian part of the Calcari Nummulitici formation, and possibly in the Priabonian of Italy and Slovenia. This taxon is herein described from Mossano, and the associated larger foraminifera (Nummulites biedai) confidently establish the age of these beds as Late Bartonian (SBZ 18), enabling the stratigraphic distribution of B. vonderschmitti to be extended to the base of SBZ 18. A new species of Glomalveolina Hottinger 1960, G. ungaroi n. sp. is formally described herein; this taxon differs from the other Middle Eocene representatives of this genus by having a lower elongation index and a larger proloculus. It is so far known only from the Late Bartonian of the Colli Berici, and represents one of the smallest alveolinids following the peak diversity of the Lutetian. Both species occur in shallow water calcarenites, and are the only representatives of the Alveolinidae in Upper Bartonian carbonate units of the Colli Berici