Pseudoniphargus callaicus n. sp. is described from a well in the vicinity of the coast in northwestern Galicia, Spain. The type materials of Ps. mateusorum Stock, longispinum Stock, and brevipedunculatus Stock are reexamined and their resemblances discussed. The new species, Ps. callaicus, appears to belong together with Ps. mateusorum and brevipedunculatus to a weakly defined Lusitanian-Azorian group. This group is more closely related to the north Spanish and Bermudian species, and to Ps. gibraltaricus from southern Spain, than to its remaining congeners. An updated checklist and key of the Iberian Pseudoniphargus species is included in this paper.