A characteristically bicolored ant belonging to the Temnothorax sordidulus species-complex is described from mountainous habitats in Iberia and named T. estel sp. nov. Three additional and closely-related taxa are newly recognized as members of the complex, including the Iberian endemics T. ibericus (Menozzi, 1922) and T. platycephalus (Espadaler, 1997) and the Pyrenean T. conatensis Galkowski Lebas, 2016. The taxonomy of all four species is reviewed and discussed within the Palearctic context. Images and an identification key are provided.