A new geophytic species of the genus Tephrocactus from northern Argentina, T. abditus, is described with the evaluation of its morphological data. The species is likely to be closely related to Tephrocactus weberi, but it markedly differs by its strictly subterranean growth, thickened and contractile tuberous roots, and short pectinate spination without central spines. The flowers are similar to those of T. weberi regarding their shape as well as range of flower colors (from yellow to red).