Comments On The Taxonomy And Geographic Distribution Of North American Part 3

Microtus oeconomus amakensis (Murie)

1930. _Microtus amakensis_ Murie, Jour. Mamm., 11:74, February 11, type from Amak Island, Bering Sea, Alaska.

When Murie (Jour. Mamm., 11:75, February 11, 1930) named the meadow mouse from Amak Island, Alaska, as _amakensis_, he arranged it as a separate species. One of us (Hall) and K. R. Kelson examined the type and topotypes of _amakensis_ in the Biological Surveys collection in the U. S. National Museum and compared them with series of _Microtus oeconomus operarius_, _M. o. sitkensis_, _M. o. elymocetes_, _M. o.

yakutatensis_, and _M. o. kadiacensis_. Among the specimens examined of the latter subspecies were 17 from Izambek Bay, Kodiak Peninsula, on the mainland opposite Amak Island, the type locality of _amakensis_.

The characters given by Murie (_op. cit._) serve to separate _amakensis_ from closely related neighboring kinds of meadow mice, but are of the degree and kind that, in this group of meadow mice, separate subspecies rather than species. Although actual intergrades are lacking, the animals from Amak Island are considered to be only subspecifically distinct and to belong to the _oeconomus_ complex. The name _Microtus oeconomus amakensis_ is applied to them.

Microtus longicaudus mordax (Merriam)

1891. _Arvicola_ (_Mynomes_) _mordax_ Merriam, N. Amer. Fauna, 5:61, July 30, type from Sawtooth (= Alturas) Lake, 7200 ft., east base of Sawtooth Mountains, Blaine County, Idaho.

1938. _Microtus longicaudus mordax_, Goldman, Jour. Mamm., 19:491, November 14.

Dalquest (Univ. Kansas Publ., Mus. Nat. Hist., 2:353, April 9, 1948) a.s.signed all the meadow mice of the species _Microtus longicaudus_ from approximately the eastern half of Washington State to _Microtus longicaudus halli_ Hayman and Holt and, in doing so, excluded the subspecies _Microtus longicaudus mordax_ from that state. This a.s.signment of specimens in Washington had the effect of separating the geographic range of _M. l. mordax_ into two parts. One part was in south-central British Columbia and the other part was mainly in the Rocky Mountain region of the United States. Hall and Kelson examined specimens in the Biological Surveys collection in the U. S. National Museum in an attempt to determine more precisely the ranges of the subspecies in southern Canada, Washington, and Idaho.

_Microtus longicaudus angustus_ [= _M. l. halli_] was described by one of us (Hall, Univ. California Publ. Zool., 37:13, April 10, 1931) as differing from _mordax_ in narrower braincase, higher skull near the anterior end of the frontals, darker coloration, and seemingly smaller size. After examining the material in the U. S. National Museum no reason is seen at the present time to amend this characterization, except to add that some specimens of _M. l. mordax_ are as dark as seasonably comparable specimens of _M. l. halli_.

Examination of specimens of _Microtus longicaudus_ from Washington east of the Cascade Range (those from the Blue Mountain area excepted) discloses that the skulls do not differ essentially from those of topotypes of _M. l. mordax_, but do differ, as outlined above, from near-topotypes of _M. l. halli_. There is considerable variation in color among the Washington-taken specimens of _Microtus longicaudus_.

Animals from the eastern flanks of the Cascades average darker than those taken, north of the Snake River, still farther east in Washington. Possibly Dalquest (_op. cit._) relied mainly upon this darker color in a.s.signing the specimens from eastern Washington to _M.

l. halli_. Relying princ.i.p.ally upon cranial characters, we conclude that most of the specimens are better referred to _M. l. mordax_ and that _M. l. halli_ is restricted, in Washington, to the Blue Mountains.

_Specimens examined of Microtus longicaudus mordax._--Total, 74, all in the Biological Surveys Collection, distributed as follows: Washington: _Okanogan_ _County_: mouth of Holmar Creek, W Fork Paysaten River, 4700 ft., 1; Conconully, 3; Twisp, 1; Omak Lake, 1200 ft., 3. _Stevens County_: 5 mi. N Colville, 1. _Pend Oreille County_: 9 mi. N Metalina, 2600 ft., 1; Sullivan Lake, 3000 ft., 3.

_Chelan County_: Sethekin, 1079 ft., 3; head of Lake Chelan, 900 ft., 12; Hart Lake, Railroad Creek, 3900 ft., 1; Entiat, 20 mi from mouth of Entiat River, 1680 ft., 13; Wenatchee, 4. _Douglas County_: Waterville, 1. _Jefferson County_: Cleveland, 2. _Kitt.i.tas County_: 2 mi. S Blewett Pa.s.s, 3000 ft., 6: Ellensburg, 1500 ft., 4. _Whitman County_: Colfax, 2. _Yakima County_: McAllister Meadows, Tieton River, 3000 ft., 3; Gotchen Cr., 5500 ft., near Sava Spring, Mt. Adams, 2. _Klickitat County_: 8 mi. S Glenwood, base Mt. Adams, 2. _Asotin County_: Anatone, 3300 ft., 4; Bly, 1000 ft., 2.

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.

1901. _Microtus miurus_ Osgood, N. Amer. Fauna, 21:64, September 26, type from head of Bear Creek, in mts. near Hope City, Turnagain Arm, Cook Inlet, Alaska.

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.

1950. _Microtus miurus paneaki_ Rausch, Jour. Washington Acad.

Sci., 40:135, April 21, type from Tolugak Lake (lat. 68 24' N, long. 152 10'), Brooks Range, Alaska.

MICROTUS MIURUS OREAS Osgood.

1907. _Microtus miurus oreas_ Osgood, Proc. Biol. Soc.

Washington, 20:61, April 18, type from Toklat River, Alaskan Range, Alaska.