Subgenus Terricola, subterraneus species group (Pavlinov and Rossolimo, 1998; Pavlinov et al., 1995a; Zagorodnyuk, 1990). Included in Pitymys subterraneus by Ellerman and Morrison-Scott (1951) or in P. majori by Corbet (1978c). However, Kratochvíl and Kral (1974), Baskevich et al. (1984), Achverdjan et al. (1992), and Baskevich (1997) provided evidence that supports daghestanicus as a separate species, a stature broadly endorsed (Gromov and Erbajeva, 1995; Pavlinov and Rossolimo, 1987, 1998; Pavlinov et al., 1995a). Closely related to M. subterraneus and M. majori (Baskevich, 1997; Macholán et al., 2001; Mezhzherin et al., 1995). Zima and Kral (1984a) reviewed chromosomal information. Bashkevich (1997) contributed other karyotypic and spermatozoal analyses and identified morphological traits potentially useful for discriminating M. daghestanicus and M. majori in sympatry.
Within M. daghestanicus, although all geographic samples possess FN = 58, those from Armenia and Azerbaijan exhibit 11 karyomorphs ranging from 2n = 38 to 54 and those from the N Caucasus uniformly have 2n = 54 (Achverdjan et al., 1992). Achverdjan et al. (1992) contrasted this pattern with M. majori (2n = 54, FN = 60) from the Caucasus and M. schelkovnikovi (2n = 54, FN = 62) from SE Azerbaijan, speculating that pine vole (subgenus Terricola) evolution in the Caucasus either resulted in species with the same 2n but different fundamental numbers (M. majori and M. schelkovnikovi) or produced the same FN but variable diploid counts (M. daghestanicus). The taxon nasarovi has been included in M. majori (Corbet, 1978c) or listed as a separate species (Pavlinov and Rossolimo, 1987; Pavlinov et al., 1995a; Zagorodnyuk, 1990). Its chromosome complement (2n = 38 or 42, FN = 58) falls within the range of karyomorphs described for M. daghestanicus, prompting Achverdjan et al. (1992) and Gromov and Erbajeva (1995) to include it as a subjective synonym.