This species is distinguished from its congeners by the following set of characters: canaliculate scales on the lateral line 38-44 (mean = 40.9, Md = 41 n = 36); scales above the lateral line 5-6 (mean = 5.8, Md = 6 n = 36); scales below the lateral line 3-4 (mean = 3.1, Md = 3 n = 36); caudal peduncle low (SL/BLD<10); body depth high in comparison to caudal peduncle depth (BD/BLD > 2); pharyngeal teeth 5/5; dentary with coronoid process wide; skull narrow with HL/ID>3. Genetic distances from the other Achondrostoma species inferred from the MT-CYTB gene sequence were: about 7.7 % with respect to A. salmantinum, 4.1 % with respect to A. occidentale, about 6-6.3 % with respect to A. oligolepis, 6.8-6.9 % with A. arcasii (here defined as the Ebro and adjacent Mediterranean rivers), and 6.6 % with Central-Eastern Duero. It has 13 autapomorphies in the mitochondrial cytochrome b gene, one of which is a transversion (Ref. 128766).