Ordovician ostracods are described for the first time from Iran, enhancing the record of this group from the Lower Palaeozoic of the Middle East. The ostracods occur in the Shirgesht Formation, in the east central part of the country, and comprise Ogmoopsis achaemenid sp. nov., Cerninella aryana sp. nov., Ordovizona amyitisae sp. nov., cf. Aechmina? ventadorni, Vogdesella sp., and podocope taxa tentatively identified as species of Longiscula, Pullvillites, and Rectella. These taxa were hitherto unknown from this region. The ostracod-bearing interval is associated with trilobites (Neseuretinus) and brachiopods (Nicolella) that suggest a late Middle Ordovician age. Although the ostracod fauna is small, it demonstrates biogeographical links at genus-level, and possibly at species-level, with the fauna of the late Middle Ordovician Travesout Formation of western France, which also lay in a peri-Gondwanan palaeogeographical setting. It also suggests the potential use of some ostracods as stratigraphical tools for correlating Ordovician rock successions between Europe and the Middle East.

Key words: Ostracoda, Palaeocopa, Podocopa, biogeography, Ordovician, Shirgesht Formation, Iran.

Mansoureh Ghobadi Pour mghobadipour@yahoo.co.uk, Department of Geology, Faculty of Sciences, University of Agricultural Sciences and Natural Resources, Gorgan, 49138-15739, Iran; Mark Williams mri@le.ac.uk, School of Earth and Environmental Sciences, University of Portsmouth, Burnaby Building, Burnaby Road, PO1 3QL, United Kingdom; present address: Department of Geology, University of Leicester, Leicester LE1 7RH, United Kingdom; Jean Vannier jean.vannier@univ-lyon1.fr, Université Claude Bernard Lyon 1, UFR des Sciences de la Terre, UMR 5125 PEPS Paléoenvironnements et Paleobiosphčre, GEODE-2, rue Raphaël Dubois, 69622 Villeurbanne cedex, France; Tőnu Meidla tonu.meidla@ut.ee, Institute of Geology, University of Tartu, 46, Vanemuise Str, Tartu 51014, Estonia; Leonid E. Popov Leonid.Popov@nmw.ac.uk, Department of Geology, National Museum of Wales, Cardiff, Cathays Park, Cardiff, CF10 3NP Wales, United Kingdom