Clethrionomys rutilus (Pallas, 1779) . Nova Spec. Quadr. Glir. Ord., p. 246.

TYPE LOCALITY: Siberia, center of Ob River delta .

DISTRIBUTION: Holarctic: in Old World, from N Scandinavia east to Chukotski Peninsula, and south to N Kazakhstan, Mongolia, Transbaikalia, NE China, Korea, and islands of Sakhalin and Hokkaido (see Corbet, 1978c; Henttonen and Peiponen, 1982); St. Lawrence Isl, Bering Sea; in New World, from Alaska east to Hudson Bay, and south to N British Columbia and extreme NE Manitoba, Canada.

SYNONYMS: alascensis, albiventer, amurensis, baikalensis, dawsoni, dorogostaiskii, glacialis, hintoni, insularis, jacutensis, jochelsoni, laticeps, latigriseus, lenaensis, mikado, mollessonae, narymensis, orca, otus, parvidens, platycephalus, rjabovi, rossicus, russatus, salairicus, tugarinovi, tundrensis, uralensis, vinogradovi, volgensis, washburni, watsoni .

COMMENTS: Conspecificity of Old and New World populations advanced by Rausch (1953) and corroborated by subsequent studies (e.g., Nadler et al., 1976, 1978; Rausch and Rausch, 1975a). European populations reviewed by Henttonen and Peiponen (1982). Variation in pattern of third upper molar and its systematic implications reported by Nakatsu (1982) for Japanese populations. North American populations revised, as C. dawsoni, by Orr (1945), and, as C. rutilus by Manning (1956). Also see account of C. gapperi .