Representatives of the Genus Viveja Bugrova (Foraminifera) from the Upper Cretaceous of Siberia and Peri-Tethys

This paper presents the results of analysis of the morphological and size-quantitative features of similar species of benthic foraminifers, Viveja globigeriniformis (Neckaja, 1948) and Viveja excavatus (Brotzen, 1936), which have a high biostratigraphic and paleogeographic significance within the Boreal-Atlantic and Arctic basins. Based on the analysis, we have confirmed the generic affiliation and validity of the species and established the variation limit of diagnostically important features. We have also determined the stratigraphic distribution of the species in the representative sections of Western Siberia and the Cis-Urals region. It has been revealed that the widest distribution of Viveja excavatus is typical of the Arctic regions of Western Siberia and that of Viveja globigeriniformis for the southern part of Western Siberia and the Cis-Urals region.