A new porcelaneous larger benthic foraminifer, Reticulotaberina jahrumiana new genus and new species, from the latest middle Eocene shallow-water carbonate platform deposits of SW Iran (Jahrum Formation, Zagros Mountains) is described. Its structure is characterized by the development of a thin alveolar layer (exoskeleton) in the marginal area of the chamber lumen and by septula and interseptal pillars (endoskeleton) in the central area. The septula build a network, whereas the interseptal pillars rise from its intersections. The intercameral foramina are concentrically arranged and are intercalated with septula. R. jahrumiana n. sp. displays a strong dimorphism: A-form has a planispiral-uncoiling subcylindrical morphology, whereas the B-form presents a flared shape with oval or compressed outline. The new taxon is included in the Praerhapydioninidae family and is so far known from the south-west of Iran. The age is late Bartonian.