A new species of the genus Cephalobus is described from natural areas in the south-eastern Iberian Peninsula. Cephalobus harpagonis sp. n. is characterised by female body length of 0.38-0.47 mm, lips amalgamated in pairs, labial probolae present as low ridges connecting tips of adjacent lips, ovary lacking flexures, spermatheca 11-12 μm long, postuterine sac very short (0.3-0.4 times corresponding body diam.), female tail conical or subcylindrical (22-31 μm, c = 13.2-17.1, c′ = 1.7-2.5) and ending in a tuberculate, often harpoon-like, mucro. Descriptions, measurements and illustrations, including SEM photographs, are also provided for C. persegnis and C. troglophilus from Spain. An identification key to Cephalobus species and a compendium of their measurements are also provided.