Discussion on Orbitoides concavatus Rahaghi 1976, Praeomphalocyclus concavatus Meriç and Çoruh 1991, Postomphalocyclus meriçi İnan 1992 and Pseudomphalocyclus blumenthali Meriç 1980

In the Upper Maastrichtian, orbitoidal benthic foraminifera are very abundant in carbonate sequence of the Tethys realm. The Tarbur Formation, in 5 Km southwest of Semirom with abundant orbitoidal benthic foraminifera to Late Maastrichtian age and 462 m thickness composed of carbonate and terrigenous rocks. In the present paper, author has reviewed new data related to species; Orbitoides concavatus Rahaghi 1976, Praeomphalocyclus concavatus Meriç and Çoruh 1991, Postomphalocyclus meriçi İnan 1992 and Pseudomphalocyclus blumenthali Meriç 1980. Among many known orbitoidal foraminifera, the Tarbur Formation yielded a new species, here in tentatively assigned to the genus Praeomphalocyclus Meriç and Çoruh. The species was first described and properly illustrated by Rahaghi, under the name of Orbitoides concavatus n. sp. Based on the morphometric data in this study and other studies in the Tethys area done by other researchers; both Orbitoides concavatus Rahaghi 1976 and Praeomphalocyclus concavatus Meriç and Çoruh 1991 are nomen nudum. Also Postomphalocyclus meriçi İnan 1992 is considered synonymous with Pseudomphalocyclus blumenthali Meriç 1980 in here. Pseudomphalocyclus blumenthali appears to be quite common in the Tarbur Formation has been reported by researchers in Turkey, Syria, Iraq, Iran, Saudi Arabia, Qatar, Oman, Yemen and Somalia. This species indicate shallow marine environments and may be restricted to the Late Maastrichtian.