Microtus miurus muriei (Nelson)
1931. Microtus muriei Nelson, Jour. Mamm., 12:311, August 24, type from Kutuk River (tributary of Alatna River), Endicott Mts., Alaska.
Rausch (Jour. Washington Acad. Sci., 40:135, April 21, 1950) proposed the name Microtus miurus paneaki, with type locality at Tolugak Lake (lat. 68° 24′ N, long. 152° 10′ W), Brooks Range, Alaska, for a meadow mouse of the subgenus Stenocranius. This place is only approximately forty miles east and north of the type locality of the earlier named Microtus muriei, also a member of the subgenus Stenocranius. Large series of specimens of this subgenus, from the Arctic Slope of Alaska, are in the Museum of Natural History of the University of Kansas. Study of these indicates that the differences, which Rausch (op. cit.:136) described as distinguishing his M. m. paneaki from M. muriei, result from differences in age of the specimens, and possibly in part from differences in seasonal condition of pelage. For example, Rausch thought that M. m. paneaki was larger than M. muriei but our specimens reveal that such is not the case. The measurements given below of the type specimen of M. muriei (after Nelson, original description) and measurements (in parentheses) of an immature female (43807 K. U.) of Microtus miurus muriei from Chandler Lake, 68° 12′, 152° 45′, 2900 ft., Alaska, show close correspondence in size. Total length, 119 (122); tail vertebrae, 24 (24); hind foot, 20 (20); condylobasal length, 24.3 (24.5); zygomatic breadth, 10.7 (11.0); greatest width of braincase, 9.0 (9.0); length of nasals, 6.5 (6.0); basal width of rostrum, 4.0 (4.3). In the light of all of the evidence now available, it seems best to treat Microtus miurus paneaki Rausch as a synonym of Microtus muriei Nelson.
Quay (Jour. Mamm., 32:95, February 15, 1951) identified fifty-eight specimens from the Seward Peninsula of Alaska as Microtus miurus oreas Osgood. Through the courtesy of Dr. Charles P. Lyman, fifteen of Quay's specimens in the Museum of Comparative Zoology at Harvard College have been examined by one of us (Hall). These specimens are as follows: Lava Lake (43378, 43379, 43381, 43382, 43386, 43467 and 43478); Mt. Boyan (43384, 43385, 43463 and 43477); Anvil Hill [= Peak], Cooper Gulch (43377, 43464 and 43473); ——? Lake, 43383. Although we are not prepared to say that these specimens are M. m. muriei, they seem to resemble M. m. muriei as closely as they do any other named form and we here refer them to that subspecies.
The facts are that a critical taxonomic study of the American specimens of the subgenus Stenocranius is required in order to ascertain the geographic variation. One of us (Hall) has examined the holotypes of the kinds named from Alaska, and the material listed by R. Baker (Univ. Kansas Publ. Mus. Nat. Hist., 5:109) of the two kinds named from Canada. The degree and nature of the variation shown by these specimens lead us to the conclusion that all are of a single species. If the American mouse is specifically distinct from any of the previously named Asiatic species—at this writing we lack material to decide this question—the named kinds from the mainland of the New World may stand as follows:
Microtus miurus andersoni Rand.
1945. Microtus andersoni Rand, Bull. Nat. Mus. Canada, 99:42, prior to June 20, type from near headwaters of Little Keel River, 5500 ft., 82 mi. W Mackenzie River on Canol Road, Mackenzie.
Microtus miurus cantator Anderson.
1947. Microtus cantator Anderson, Bull. Nat. Mus. Canada, 102:161, January 24, type from mountain top near Tepee Lake, 61° 35′ N, 140° 22′ W, N slope Elias Range, Yukon Terr.
Microtus miurus miurus Osgood.