|Distribution:||S Finland and Baltic region (Miljutin, 1997, 1998; Timm et al., 1998), eastwards through S Urals (Gileva et al., 1996) and Novosibirsk suburbs in W Siberia (Yakimenko and Kryukov, 1997) to SW margin of Lake Baikal, south through the Caucasus (Baskevich, 1996b) and probably NW Iran, and across the Ukraine in the north and Turkey in the south (Kryštufek and Vohralík, 2001) to E Slovakia (Mošanský, 1994), E and S Romania (Zima et al., 1981), Bulgaria, Greece, Macedonia and S Serbia and Montenegro (Petrov, 1992), and E Albania; accidentally introduced to the Arctic Svalbard Archipelago (Fredga et al., 1990; Yoccoz et al., 1993; as epiroticus). Meyer et al. (1996) provide the best map.|
Subgenus Microtus, arvalis species group (Pavlinov and Rossolimo, 1987, 1998; Pavlinov et al., 1995a; Zagorodnyuk, 1990). Populations referable to this E European species (2n = 54, FN = 56), first separated from M. arvalis by Meyer et al. (1972), have been listed or discussed as subarvalis (Corbet, 1978c), epiroticus (Petrov and Ruzic, 1982), or rossiaemeridionalis (Sokolov and Bashenina, 1994). Nomenclatural usage reviewed by Fredga (1995); Masing (1999) consolidated reports over the last 30 years spread under those epithets. The senior status of levis remains provisional.
Microtus rossiaemeridionalis is accepted by most researchers (Gromov and Erbajeva, 1995; Mitchell-Jones et al., 1999; Zagorodnyuk, 1991a), following the assertions of Malygin and Yatsenko (1986), but others still prefer subarvalis (Mazurok et al., 1995) or epiroticus (Vohralík and Sofianidou, 1992a). Vohralík and Sofianidou (1992a:364), while accepting Malygin and Yatsenko’s conclusions, noted that "a finite solution concerning the correct name of this vole cannot be made until the vole forms described earlier from northern Iran (above all M. mystacinus) will be revised. That is why we prefer to use the commonly used name M. epiroticus in the meantime." Zagorodnyuk (1991b) illustrated and described cranial traits useful for distinguishing rossiaemeridionalis from M. arvalis, and Masing (1999) applied Zagorodnyuk’s characters and new ones to distinguish large series of "rossiaemeridionalis" (2n = 54) and M. arvalis (2n = 46) with known karyotypes. He also confirmed that the type series of Miller’s (1908) M. levis (included in M. arvalis by Ellerman and Morrison-Scott, 1951) exhibited features typical of "rossiaemeridionalis" but not M. arvalis. Masing’s (1999) identity is convincing and liberates vole researchers from "the mouthful name M. rossiaemeridionalis" (Fredga, 1995:95). Whether levis is the oldest valid name awaits identity of mystacinus (de Filippi, 1865; see Ellerman and Morrison-Scott, 1951:698) from the Elburz Mtns in N Iran, as Vohralík and Sofianidou (1992a) had cautioned. Lay (1967) firmly associated the holotype and cotypes of mystacinus with M. arvalis, not M. socialis which occurs in the same region, but rossiaemeridionalis had not yet been appreciated as distinct. Reexamination of the holotype of mystacinus is needed.
Abundant cytological and morphological comparisons with the obscurus form of M. arvalis underscore the specific distinctness of M. levis (Gavrila et al., 1986; Gilvea et al., 1996; Kral et al., 1981; Kratochvíl, 1982b; Meyer et al., 1972; Naumova et al., 1990; Zagorodnyuk, 1991a, b; Zima et al., 1991), as do analyses of allozymes (Mezhzherin et al., 1993) and cytochrome b sequences (Conroy and Cook, 2000a). High-resolution G-banding relates M. levis most closely to M. transcaspicus within the M. arvalis species group (Mazurok et al., 1996b), an affinity supported by phylogenetic analyses of chromosomal, morphological, and hybridization data (Meyer et al., 1996). Regional chromosomal variation reported for W Siberia (Yakimenko and Kryukov, 1997), the Caucasus (Baskevich, 1996b), and Urals (Gileva et al., 1996); chromosomal and subchromosomal mapping documented by Mazurok et al. (1995). Albumin evolution using microcomplement fixation compared with M. thomasi (Nikoletopoulos et al., 1992). Arvicoline examplar used to quantify gene expression patterns, development, and topography in the evolution of mammalian teeth (Jernvall et al., 2000). Microtus arvalis and M. levis broadly overlap in distribution (Meyer et al., 1996:129; Zagorodnyuk, 1991b:30) and occur sympatrically in a few regions (Meyer et al., 1996; Tikhonov et al., 1998). Gromov and Erbajeva (1995) included caspicus as a subspecies of M. arvalis, but Malygin and Luis (1996) demonstrated its identity with M. levis.