The first record of the genus Isurichthys (Perciformes, Ariommatidae) in the Lower Oligocene of the Northern Caucasus

An ariommatid fish, Isurichthys breviusculus sp. nov. (Perciformes), from the Lower Maikopian (Lower Oligocene) of the northern Caucasus (Apsheronsk District) is described based on an almost complete skeleton. This is the first record of the Oligocene genus Isurichthys in the Caucasus. Direct evidence of the presence of a toothed pharyngeal sac in the oesophagus of Isurichthys is obtained for the first time. Of two known species of Isurichthys, the new species is closer to I. roumanus Baciu et Bannikov, 2004 from the Oligocene of Romania. The fossil record of Stromateoidei sensu stricto is reviewed.