Arvicolini. Although systematists agree that Lasiopodomys belongs in this tribe, they have disputed its generic status. G. M. Allen (1940) treated Lasiopodomys as a full synonym of Phaiomys, included in Microtus as a subgenus. Others have relegated it to a separate subgenus of Microtus (Corbet, 1978c; Corbet and Hill, 1991; Ellerman and Morrison-Scott, 1951). Hinton (1926a) enumerated the many features that isolate Lasiopodomys: very short pinnae; elongate front claws; claw rather than nail on thumb; plantar surfaces densely furred; three labial salient angles on a simple M3, not four on a relatively elaborate molar; anterolabial margin of M3 concave, not angular; cusps elongate, not triangular; and m1 cap with only lingual secondary wing, not labial and lingual wings (Gromov and Polyakov, 1977, offered additional traits). Both neontologists and paleontologists have broadly acknowledged Hintonís treatment (Ellerman, 1941; Gromov and Erbajeva, 1995; Gromov and Polyakov, 1977; Pavlinov and Rossolimo, 1987, 1998; Pavlinov et al., 1995a; Repenning, 1992; Repenning et al., 1990; Smorkacheva et al., 1990; Zagorodnyuk, 1990; Zheng and Li, 1990). In an allozymic analysis of Palaearctic voles, Mezhzherin et al. (1993) documented membership of L. brandtii in the same clade as Microtus fortis and M. gregalis. Except for their study, the allocation of Lasiopodomys to Microtus has not issued from a data-rich and taxonomically broad phylogenetic study; until such evidence prescribes otherwise, Lasiopodomys should be retained as a genus following Hinton (1926a).
Gromov and Polyakov (1977) presciently described the two extant species as remnants of an ancient group that was more abundant in the past, a view consistent with that of Repenning (1992). Based on M3 and m1 patterns, he allocated several extinct species to Lasiopodomys, dating from the early Pleistocene in Eurasia (1.5-1.2 million years ago), Beringia (1.6-1.3 million years ago), and North America west of the Rockies (1.2 million years ago), and from the late Pleistocene (850,000 years ago) in North America east of the Rockies (also Zheng and Li, 1990). Repenning (1992) placed the evolution of Lasiopodomys from Allophaiomys in Eurasia (about 1.5 million years ago), and both genera reached North America at different times (see also Chaline, 1999, for discussion of Allophaiomys); in neither region did Lasiopodomys give rise to any Microtus. Other authorities do not share Repenningís notions about the pivotal evolutionary significance of the Lasiopodomys morphotype, and instead recognize only a great range of variation in Allophaiomys, from which most members of Arvicolini were derived (see Agusti, 1991; Chaline et al., 1999; R. A. Martin, 1987, 1989b, 1995).