The morphological ontogeny of Cerachipteria iturrondobeitiai sp. nov. from northern Spain is described and illustrated. The adult of this species has wide, long prodorsal lamellae, protruding beyond the rostrum, as in other genera of Achipteriidae. However, the lamellae are separated as in other species of Cerachipteria Grandjean, 1935. In C. iturrondobeitiai, the translamella can be present, incomplete or absent, whereas most congeners lacks the translamella, except for C. jugata Mihelčič, 1956, in which it is well-formed. The ovipositor of C. iturrondobeitiai is unusual because it bears seven pairs of coronal setae, instead of three pairs in other species of Achipteriidae. The adult of C. iturrondobeitiai is similar to C. digita Grandjean, 1935, but differs from it mainly by the location of porose areas A2 and A3 and seta lm on the notogaster and the shape of the bothridial seta. The juveniles of C. iturrondobeitiai are plicate, with most prodorsal setae minute, as in other species of Achipteriidae, and the larva lacks seta h₃. In C. iturrondobeitiai, the gastronotal setae of c-series are also minute, whereas in other species these setae are longer and thicker, or at least c₁. The leg claws of this species are smooth. The ontogeny of C. iturrondobeitiai is compared with some other species of Achipteriidae, and the adult is compared with congeners.