A new fossil Aphanius species from the Upper Miocene of Armenia (Eastern Paratethys).

A new fossil fish species, Aphanius yerevanicus (Cyprinodontiformes, Cyprinodontidae), is described based on a well preserved, articulated skeleton from the early Upper Miocene of Yerevan, Armenia (Eastern Paratethys). The fish-bearing sediments contain a fossil assemblage indicative of a euryhaline environment. The new species differs from previously described fossil Aphanius species by the possession of caudal ribs articulating with the first haemal spine, a remarkably low number of abdominal vertebrae and the morphology of the tricuspid jaw teeth. Co-occurence of Aphanius yerevanicus with Prolebias mutilus Bogachev, 1936 at Yerevan suggests that sympatric occurrence of several members of the Cyprinodontiformes has continued successfully throughout the Miocene in euryhaline environments where competition between these forms and other fishes were low because of the unstable salinity.