Orbitolinopsis cenomaniensis n. sp., a new larger benthic foraminifera (Orbitolinidae) from the middle-?late Cenomanian of the Sarvak Formation (SW Iran, Zagros Zone): a regional marker taxon for the Persian Gulf area and Oman

Abstract

A new orbitolinid is described as Orbitolinopsis cenomaniensis n. sp. from the middle-?late Cenomanian of the Sarvak Formation, Zagros Zone, SW Iran. It is characterized by a high-conical test, a simple embryo consisting of proloculus and deuteroconch in subapical position, a rather narrow marginal zone and a prominent central zone with cupules that can present a jagged outline. The regular occurrence of one short rafter is considered a species characteristic of the species, one case that is also encountered in other dictyoconid taxa (e.g., Montseciella, Paracoskinolina, Simplorbitolina, Valserina). Single sporadic rafters have been reported from the early Albian Orbitolinopsis ajoensis Schlagintweit et al. demonstrating a distinct trend towards an increasing in morphological complexity. The Iranian find represents the first record of Orbitolinopsis from the Cenomanian. Like several other taxa of larger benthic foraminifera (agglutinating and porcelaneous), O. cenomaniensis is here considered an endemic taxon for the Arabian Plate.