Part 4

Range.--Known only from two localities on Revillagigedo Island, Alaska.

Diagnosis.--A short-tailed, dark-colored member of the gapperi group. Dorsal stripe wide, between Chestnut and Bay (capitalized color terms after Ridgway: Color Standards and Color Nomenclature. Washington, D. C., 1912), with slight mixture of black-tipped hairs; sides and venter heavily washed with Ochraceous-Tawny. Skull flattened; rostrum proportionately short and wide; auditory bullae relatively uninflated.

Comparisons.--From topotypes of Clethrionomys gapperi wrangeli, C. g. solus differs as follows: dorsal stripe wider and slightly brighter; sides brighter; venter more heavily washed with Ochraceous-Tawny (heavy wash in all 13 C. g. solus examined; in C. g. wrangeli no wash in 11, slight wash in 16, and heavy wash in only one); nasals, alveolar extent of upper cheek-teeth and incisive foramina shorter; skull shallower when measured with tympanic bullae included; rostrum averages slightly broader.

From C. g. phaeus of the adjacent mainland, C. g. solus differs in: dorsal stripe slightly darker; ventral wash more prominent; tail shorter; skull smaller in all parts measured except that nasals are approximately the same length, auditory bullae notably smaller and teeth notably narrower.

Measurements.--External and cranial measurements of adults are shown in table 1.

Remarks.--Bailey (Proc. Biol. Soc. Washington, 11:120, May 13, 1897) referred 17 specimens from Loring to his newly named species, E. wrangeli [= Clethrionomys gapperi wrangeli] but based his description on specimens from Wrangell Island. He pointed out (loc. cit.) that all of the specimens from Loring had the "bellies strongly washed with buffy-ochraceous, while more than half of those from Wrangell have whitish bellies."

Specimens examined.--Total, 13, all in the Biological Surveys Collection, U. S. National Museum, from the following localities: Alaska: Revillagigedo Island: Loring, 10; mouth of Fish Creek, Ketchikan, 3.

Clethrionomys gapperi stikinensis, new subspecies

Type.--Male, adult, skin and skull, No. 30735, Museum of Vertebrate Zoology, University of California; from Stikine River at Great Glacier, British Columbia; obtained on August 13, 1919, by J. Dixon; original number 7691.

Range.--Known only from the lower Stikine River Valley of British Columbia and the Cleveland Peninsula of Alaska.

Diagnosis.--A medium-sized, dark-colored member of the gapperi group. Dorsal stripe wide, near Auburn with mixture of black-tipped hairs; sides and venter washed with Ochraceous-Tawny. Skull small; cheek-teeth narrow; auditory bullae relatively uninflated.

Comparisons.--From topotypes of Clethrionomys gapperi wrangeli, C. g. stikinensis differs as follows: dorsal stripe slightly wider and brighter; sides slightly duller (lacking the olivaceous wash of C. g. wrangeli); all cranial measurements taken averaging smaller except height of skull, which is approximately the same; alveolar length of upper tooth-row and length of incisive foramina notably shorter; auditory bullae less inflated; cheek-teeth much narrower.

From topotypes of C. g. phaeus, C. g. stikinensis differs as follows: dorsal stripe and sides darker; auditory bullae less inflated; cheek-teeth narrower; skull smaller in most measurements taken (see table 1).

From topotypes of C. g. solus, C. g. stikinensis differs as follows: dorsal stripe lighter (more tawny underwash); ventral wash of buffy much paler (especially noticeable around mouth and on throat); zygomatic and lambdoidal breadths greater; skull deeper; auditory bullae more inflated; cheek-teeth slightly heavier.

TABLE 1. External and cranial measurements of Clethrionomys.

N | | | | | | | | | | | u | | | | | | | | | | | m | | | | | | | | | | L | b | | | | | | | | | | e | e | | | | | | | | | | n | r s | | | | | | | | | | g | e | | | | | | | | | | t | o x | | | | | | | | | | h | f | | | | C | | | | | | | o | | | | o | | | | | | o | i r | | | | n | | | | | | f | n | | | | d | | L | | A | B | | d s | | | | y | Z | a | | l | r | i | i p | | | | l | y | m | L | v | e | n | v e | | | | o | g | b | e | e u| a | c | H i c | | | | b | o | d | n | o p| d | i | e d i | | | | a | m | o | g | l p| t | s | i u m | T | | | s | a | i | t | a e| h | i | g a e | o | | | i | t | d | h | r r| | v | h l n | t | | | l | i | a | | | o | e | t s | a | | H | a | c | l | o | l t| f | | m | l | | i | r | | | f | e o| | f | o o e | | | n | | b | b | | n o| r | o | f f a | l | | d | l | r | r | n | g t| o | r | s | e | | | e | e | e | a | t h| s | a | s e u | n | T | f | n | a | a | s | h | t | m | k a r | g | a | o | g | d | d | a | r| r | i | u c e | t | i | o | t | t | t | l | o o| u | n | l h d | h | l | t | h | h | h | s | f w| m | a | l

Clethrionomys gapperi solus, Loring

Male type |133|33 |20 | 22.3 | 12.5 |10.9 |6.8 |5.1 |3.4 |5.3 | 9.0 Male 5 av. |131|34 |20 | 22 | 12.7 |10.8 |6.8 |5.3 |3.5 |5.1 | 9.1 min.|128|33 |19 | 21.8 | 12.5 |10.5 |6.7 |5.1 |3.3 |5.0 | 8.9 max.|133|36 |20 | 22.3 | 13.0 |11.2 |7.1 |5.5 |3.6 |5.3 | 9.5 Female 5 av. |128|34 |19 | 21.3 | 12.5 |10.5 |6.5 |5.4 |3.5 |4.9 | 9.2 min.|124|31 |19 | 20.9 | 12.3 |10.3 |6.0 |5.2 |3.3 |4.8 | 8.9 max.|140|36 |20 | 21.7 | 12.7 |10.7 |7.0 |5.6 |3.6 |5.0 | 9.5

Clethrionomys gapperi stikinensis, Stikine River at Great Glacier

Male type |145|39 |20 | 23.2 | 13.9 |11.4 |7.3 |5.0 |3.1 |5.5 | 9.5 Male 4 av. |136|35 |20 | 22.2 | 13.0 |11.1 |6.8 |5.2 |3.4 |5.2 | 9.4 min.|132|33 |19 | 21.5 | 12.3 |10.7 |6.5 |5.0 |3.1 |5.1 | 9.1 max.|145|39 |20 | 23.2 | 13.9 |11.4 |7.3 |5.6 |3.5 |5.5 | 9.7 Female 7 av. |134|33 |19 | 21.8 | 12.7^6*|10.9 |7.0 |5.4 |3.4 |5.1 | 9.5 min.|125|30 |19 | 21.5 | 12.5 |10.5 |6.7 |5.3 |3.2 |5.0 | 9.2 max.|147|35 |20 | 22.2 | 12.9 |11. |7.1 |5.6 |3.7 |5.3 | 9.8

Clethrionomys gapperi wrangeli, Wrangell

Male 9 av. |139|36 |19 | 23.4^8| 13.3 |11.4^8 |7.3 | .6 | .6 | .6 | 9.6^8 min.|130|31 |18 | 22.9 | 13.0 |10.9 |7.1 |5.5 |3.3 |5.4 | 9.2 max.|151|43 |20 | 23.9 | 13.7 |11.8 |7.6 |5.8 |4.0 |5.8 |10.1 Female 16 av.|134|34 |18^15| 23.2 | 13.3 |11.2^13|7.3 |5.8 |3.5 |5.5 | 9.4 min.|123|28 |17 | 22.4 | 12.6 |10.7 |6.9 |5.5 |3.2 |5.2 | 9.0 max.|156|45 |20 | 24.1 | 14.1 |11.8 |8.0 |6.1 |3.7 |5.9 | 9.7

Clethrionomys gapperi phaeus, Chickamin River

Male 5 av. |148|47 |20 | 23.0^4| 13.7^4|11.3^4 |7.5^4|5.3^4|3.5^4|5.3^4| 9.7^3 min.|138|38 |20 | 22.3 | 13.0 |11.1 |7.1 |5.3 |3.4 |4.9 | 9.3 max.|159|51 |21 | 23.8 | 14.6 |11.8 |7.7 |5.6 |3.8 |5.6 |10.0 Female 4 av. |153|49 |20 | 23.1^3| 13.4 |11.2^3 |7.6^3|5.2 |3.7 |5.3 | 9.6^3 min.|140|44 |20 | 22.4 | 12.8 |10.8 |7.3 |5.0 |3.4 |5.1 | 9.2 max.|164|56 |20 | 24.2 | 13.6 |11.4 |7.7 |5.3 |3.9 |5.5 | 9.8

*Superior numbers denote the number of individuals averaged.

Measurements.--External and cranial measurements of adults are given in table 1.

Remarks.--Morphologically C. g. stikinensis shows greater resemblance to C. g. solus of Revillagigedo Island, than to the geographically adjacent subspecies C. g. wrangeli and C. g. phaeus. Possibly the original stock of C. g. solus was rafted to Revillagigedo Island from the Cleveland Peninsula.

Specimens examined.--Total, 29, all in the Museum of Vertebrate Zoology, University of California, distributed as follows: British Columbia: Stikine River at Great Glacier, 22; Stikine River at Flood Glacier, 3. Alaska: Bradfield Canal, 1; Helm Bay, 2.