Iberolacerta (cyreni) martinezricai has a karyotype of 2n = 36, all acrocentric macrochromosomes. Nucleolar Organizer Regions (NORs) are interstitially situated on a medium small (MS-type) chromosome, a derived character shared with I. cyreni, which differs in details of W-sex chromosome: W is heteromorphic and heterochromatic in I. cyreni, while it is homomorphic and euchromatic in I. (c.) martinezricai. Osteologically, it is characterized by the presence of a triangular-shaped expansion of the squamosal towards the supratemporal fenestra, and by the presence of seven (instead of six) posterior short ribbed presacral vertebrae. These odd characters probably became fixed in this relic taxon by imbreeding. Its differences and affinities are discussed, proposing a specific status for this taxon.