Subgenus Microtus. Formerly placed in subgenus Terricola, subterraneus species group (Chaline et al., 1988; Pavlinov and Rossolimo, 1998; Pavlinov et al., 1995a). A distinctive species reviewed by Niethammer (1982l) and Zagorodnyuk and Zima (1992); karyotype with 2n = 32, lower than any species of Terricola (Zima and Kral, 1984a). Zagorodnyuk (1989) systematically reviewed species in the subgenus Terricola and described zykovi, now recognized as the subspecies occurring in the E Carpathians (Mitchell-Jones et al., 1999). Presence in those mountains originally based on morphology until Zagorodnyuk and Zima (1992) added chromosomal evidence to conclusively identify M. tatricus. Zagorodnyuk et al. (1992) also documented M. tatricus and M. subterraneus in the E Carpathian Mtns in the Ukraine, corrected misidentifications as M. agrestis or M. arvalis, and described diagnostic morphological traits.

Zagorodnyuk and Zima (1992) proposed that the pitymyan rhombus in M. tatricus, a cardinal dental trait for assigning it to the subgenus Terricola, was acquired independently and considered the species to be related to those in subgenus Microtus. Haring et al. (2000:237) corroborated such a relationship, using DNA sequence analyses that disclosed M. tatricus "as a distinct lineage that split off prior to the radiation of the multiplex complex, perhaps shortly after the separation of the M. subterraneus lineage." Zagorodnyuk and Zima (1992) propounded a biogeographic scenario to explain the Pleistocene differentiation of M. tatricus and its isolation in the Carpathians. Martínková and Dudich (2003) consolidated all distribution records and discussed the strong insularity of the species’ distribution.