Much remains to be learned about the past diversity and evolutionary history of the Clupeidae (herrings, shads and allies), owing to the frequently subtle differences between modern taxa and the moderate preservational quality of some fossils. In this study, new clupeid fossils are described from a new locality from the upper Miocene of the Serres Basin, Northern Greece. The fossils are well-preserved articulated skeletons, exhibiting features such as a small size (<150 mm in standard length), slender body, two pairs of bullae, at least six parietal–postparietal striae, two supramaxillae, five branchiostegal rays, 10 supraneurals, 40–42 vertebrae, eight or nine pelvic fin rays, 17 rays in the dorsal and 16–19 rays in the anal fin, last two fin rays of the anal fin not elongate, and belly fully scuted. The new fossils cannot be attributed to any modern genus, though they most closely resemble the monotypic genus Hilsa, which today inhabits the Indo-Western Pacific. Detailed comparisons with all fossil clupeid taxa from the Cenozoic indicate that the new fossils constitute a new species, which is tentatively attributed to the fossil genus Pseudohilsa, as Pseudohilsa nikosi Kevrekidis, Arratia, and Reichenbacher sp. nov. Clupeids reportedly similar to the modern-day tropical Hilsa have been previously described from the Pliocene of the Black Sea and the middle Miocene of the Caspian Sea. This is, however, the first time that a possible fossil Hilsa relative has been described from the Mediterranean.

Key words: Teleostei, Pseudohilsa , Kelee shad, osteology, Miocene, Paratethys, Tethys, Serres Basin, Aegean Sea.

Charalampos Kevrekidis [ch.kevrekidis@campus.lmu.de ] and Bettina Reichenbacher [b.reichenbacher@lrz.unimuenchen. de ], Ludwig-Maximilians-Universität München, Department für Geo- und Umweltwissenschaften, Paläontologie & Geobiologie, GeoBio-Center, Richard-Wagner-Str. 10, 80333, Munich, Germany. Gloria Arratia [garratia@ku.edu], Biodiversity Institute and Department of Systematic and Evolutionary Biology, The University of Kansas, Dyche Hall, Lawrence, Kansas, 66045, USA. Nikos Bacharidis [nbaharidis@gmail.com], Epidavrou 90, Pylaia, 54454, Thessaloniki, Greece.