Vorontsov et al. (1977b) distinguished four species groups based upon biochemical data: the monotypic S. nehringi, S. leucodon, and S. microphthalmus groups, and the last containing S. graecus, S. polonicus, S. arenarius, and S. giganteus. The species discriminated biochemically are the same as those defined by Ognev (1963a) and Topachevskii (1969) using morphological traits and by Lyapunova et al. (1974) using chromosomal evidence. To these seven was added S. ehrenbergi. Although Savič and Nevo (1990:133) acknowledged eight extant species, they concluded that the systematics is unrealistic because "it is based primarily on classical morphology, ignoring the central phenomenon of Spalacid evolution, i.e., chromosomal speciation which suggests that more than 30 living karyotypes, or species have been described and the end is not yet in sight." Based upon new information published since 1993 or reinterpretation of older data, we add five additional species, realizing that 13 likely underestimates actual species diversity in Spalax, for Nevo et al. (1995:226) later remarked that the "40-50 karyotypes described in Spalacidae … represent presumptive good biological sibling species" and that "the morphological species concept does not hold in Spalax."

Peshev (1989a, b) illuminated interspecific differences among five species, as well as sexual dimorphism within each, using morphometric techniques. The cephalic arterial system and its phylogenetic significance was described by Bugge (1971a, 1985), and aspects of various morphological systems, particularly masseter musculature and gastrointestinal structure, summarized by Vorontsov (1979, 1982). Pasichnyk (1992) contrasted structure and function of the maxillary region in several species of Spalax, contrasting them with Ellobius, Rhombomys, Rattus, and Cricetus. Zagorodnyuk (1992b) discussed taxonomic status of names based on Ukrainian samples. Evolutionary history of Spalax extends from the early Pliocene of Europe (Kowalski, 2001; Topachevskii et al., 1998), Pleistocene of North Africa, and middle Pleistocene of SW Asia (McKenna and Bell, 1997; see reviews in Nevo et al., 2001, and Ünay, 1999).