The Lower Eocene sediments in the southwestern Seyitgazi (EskiAYehir) region include shallow-water rhythmic deposition of claystones, limestones, clayey limestones, and sandy limestones. The Lower Eocene unit in the northwestern Tosya (Kastamonu) region is composed of shallow-water limestones. Both units contain a new soritid foraminiferal genus, Cyclopertorbitolites (with the type species Cyclopertorbitolites tokerae sp. nov.). Cyclopertorbitolites tokerae gen. et sp. nov. is described in the Middle Ilerdian-Lower Cuisian sediments of Seyitgazi and in the Middle Ilerdian limestones of Tosya in this study. It is characterized by the presence of regular annular chambers with rectangular or subrectangular chamberlets at the juvenile stage and a porcellaneous lamina on either side of the test.