Part 9

Fiber spatulatus Osgood, N. Amer. Fauna, 19:36, October 6, 1900. (Type from Lake Marsh, Yukon, Canada.)

Ondatra zibethica spatulata Miller, N. Amer. Land Mamm. 1911, p. 231, December 31, 1912.

Specimens examined.--Total 2, as follows: Alaska: N side Salcha River, 600 ft., 25 mi. S and 20 mi. E Fairbanks, 1; E side Deadman Lake, 1800 ft., 15 mi. NE Northway, 1.

Remarks.--One muskrat was shot in an old beaver pond on the north side of the Salcha River. A skull from a carcass, that had been left by a trapper the previous winter, was obtained at Deadman Lake.

Phenacomys intermedius mackenzii Preble

Lemming Mouse

Phenacomys mackenzii Preble, Proc. Biol. Soc. Washington, 15:182, August 6, 1902. (Type from Fort Smith, Slave River, Mackenzie, Canada.)

Phenacomys intermedius mackenzii Crowe, Bull. Amer. Mus. Nat. Hist, 80:403, February 4, 1943.

Specimen examined.--One from Yukon Territory: SE end Dezadeash Lake.

Remarks.--A subadult taken only a few miles from the Alaskan border in Yukon Territory constitutes an extension of the known range of this species to the northwest. The mouse is evidently rare or irregular in its distribution since Alcorn did considerable trapping in the area from which only one was taken.

Microtus pennsylvanicus

Pennsylvania Meadow Mouse

The Pennsylvania meadow mouse is an abundant mammal along the Alaska Highway. Alcorn obtained specimens at most of his trapping stations, frequently in company with Microtus oeconomus at the more northern localities. A preferred habitat was grassy areas and willow clumps along streams or at the edges of lakes. The best catches were made along well-used runways, especially where there were piles of cut grass. These runways were used also by Clethrionomys and other small animals. Specimens of M. pennsylvanicus were frequently taken in the daytime; one was taken on June 29 as it was swimming at the edge of a small lake near the junction of the Liard River and Irons Creek in British Columbia.

Lacking sufficient comparative material in the past, most workers have considered that M. pennsylvanicus ranges without appreciable geographic variation throughout most of northwestern Canada and Alaska, where it has been referred to the subspecies, M. p. drummondii. Dale (1940), in studying collections made in British Columbia and southeastern Alaska, found evidence of geographic variation and recognized two new subspecies; thus he not only pointed out geographically variable characters but reduced the size of the range ascribed to M. p. drummondii. A later work by Rand (1943) considered the northwestern populations of M. pennsylvanicus as being too variable to show distinctive groupings. The large collection made by Alcorn offers evidence that other separable subspecies with constant characters are present. Study of this material indicates the presence of two unnamed subspecies, which are named and described as follows:

Microtus pennsylvanicus alcorni new subspecies

Type.--Female, adult, skin with skull, No. 21552, Univ. Kansas, Mus. Nat. Hist., 6 mi. SW Kluane, 2550 feet elevation, Yukon Territory, Canada; 24 August 1947; obtained by J. R. Alcorn; original No. 5240.

Range.--Extreme southwestern Yukon Territory and adjacent parts of Alaska as far south as Haines, as far north as Northway, and as far west along the Alaskan coast as Anchorage and Tyonek.

Diagnosis.--Size large (see measurements); color of upper parts near (l) Brussels Brown; skull noticeably ridged; zygomatic arches heavy, rounded and relatively short; rostrum heavy; auditory bullae not greatly expanded; maxillary teeth relatively heavy and low-crowned.

Comparisons.--From M. p. drummondii (specimens from vicinity of Whitehorse, Y. T., Trutch, B. C., and Kinuso, Alberta), M. p. alcorni differs as follows: Averaging larger in all measurements taken except lengths of tail and hind foot, which are the same; color of upper parts slightly paler and more gray and less brown; underparts paler; zygomatic arches heavier, rounder and shorter; skull proportionately more massive, except the auditory bullae which are less inflated; maxillary teeth heavier and lower-crowned.

From M. p. rubidus (specimens from Atlin, B. C.), M. p. alcorni differs as follows: Averaging larger in all cranial measurements taken except length of the maxillary tooth-row which is the same; color of upperparts more gray and less brown; underparts darker; skull longer with longer nasals and heavier zygomatic arches; skull of adult more heavily ridged.

From M. p. admiraltiae (specimens from Admiralty Island), M. p. alcorni differs as follows: Averaging larger in all measurements taken; color of upper parts more gray and less brown, underparts darker.

Remarks.--Microtus p. alcorni is a well-defined subspecies differing markedly from adjacent subspecies by a larger and heavier skull and broader, more rounded and heavier zygomatic arches. Characters examined in the specimens available are constant. Specimens from Haines are slightly darker than those from Kluane. An adult (No. 21534, UKMNH) from Northway has slightly more inflated auditory bullae than those from Kluane. An adult from Tyonek (No. 986, UKMNH) has richer brown upper parts. Measurements of this specimen resemble closely those of animals from Kluane, although the rostrum is noticably heavier.

Several adults were available from many of the localities of occurrence of M. p. alcorni. At the locality 9 miles west and 4 miles north of Haines, there were four which were considered to be old adults. These four had larger measurements than others considered to be fully adult. In addition, the skulls were larger and more rugged. There were occasionally old adults in other series. For the sake of uniformity, I have not considered these aforementioned old adults in the comparative studies of younger adults. This subspecies is named in honor of J(oseph). R(aymond). Alcorn, the collector.

Measurements.--Average and extreme measurements of six adults of both sexes of M. p. alcorni from the type locality are as follows: Total length, 162 (149-172); length of tail, 43 (39-45); condylobasal length, 26.3 (25.6-26.3); basal length, 25.2 (24.2-25.9); length of nasals, 7.3 (6.9-7.5); zygomatic breadth, 15.3 (14.9-15.6); breadth across auditory bullae, 12.8 (12.4-13.2); alveolar length of upper molariform tooth-row, 6.4 (6.1-6.7). Seven adults of both sexes from 9 miles west and 4 miles north of Haines have the following measurements: 158 (148-165); 45 (41-50); 26.1 (25.5-26.8); 24.8 (24.4-25.7); 7.3 (7.0-7.6); 14.9 (14.3-15.1); 12.2 (11.8-13.0); 6.2 (5.9-6.3).

Specimens examined.--Total 65, distributed by localities of capture as follows and deposited in the University of Kansas Museum of Natural History: Alaska: E side Deadman Lake, 1800 ft., 15 mi. SE Northway, 7; 1 mi. NE Anchorage, 100 ft., 1; Tyonek, Cook's Inlet, 1; E side Chilkat River, 100 ft., 9 mi. W and 4 mi. N Haines, 37. Yukon Territory: 6 mi. SW Kluane, 2250 ft., 14; SW end Dezadeash Lake, 2; 11/2 mi. S and 3 mi. E Dalton Post, 2500 ft., 3. Specimens reported by Osgood (1904:35) have not been seen by me but may be of this subspecies, and are tentatively referred to it. These are from the following localities in Alaska: Lake Clark near Keejik, near the mouth of the Chulitna River, and Kakhtul River near the junction with the Malchatna.

Microtus pennsylvanicus tananaensis new subspecies

Type.--Female, adult, skin with skull, No. 21509, Univ. Kansas, Mus. Nat. Hist., Yerrick Creek, 21 mi. W and 4 mi. N Tok Junction, Alaska; 20 July 1947; obtained by J. R. Alcorn; original No. 5023.

Range.--East-central Alaska as far south as Tok Junction, as far west as Mt. McKinley, as far north as Fairbanks and as far east as Eagle.