Seminemacheilus ahmeti, new species, is described from Sultan Marshes, Kızılırmak Basin, Kayseri Province, Turkey. This species is distinguished from the other members of the genus by a combination of the following characters: irregular dark brown spots on the dorsal and lateral faces of the head, longer head with blunt snout, reduced and separated orbitosphenoids, and wider and larger actinosts and connection of the coracoid to the cleithrum in pectoral girdle. It is also diagnosed from S. ispartensis and S. lendlii by seven fixed, diagnostic nucleotide substitutions in the mtDNA COI barcode region, and a K2P nearest-neighbour distance of 5.5% and 2.1%, respectively.