Sorex ugyunak
| Barren Ground Shrew
(Sorex ugyunak) | |
|---|---|
| Range | |
 | |
| Taxonomic classification | |
| Order: | Eulipotyphla |
| Suborder: | Erinaceota |
| Family: | Soricidae |
| Subfamily: | Soricinae |
| Tribe: | Soricini |
| Genus: | Sorex |
| Subgenus: | Otisorex |
| Species group: | Sorex cinereus group |
| Binomial details | |
| Sorex ugyunak R. M. Anderson & Rand, 1945 | |
| Other resources | |
| Full taxonomic details at MDD | |
Sorex ugyunak has been included in Sorex cinereus, but genetic and morphological evidence supports its recognition as a distinct species (Van Zyll de Jong, 1976; Van Zyll de Jong, 1991; Hope et al., 2012).
Description
From Naughton (2012): "This small shrew is distinctively coloured. It has a light- to medium-brown stripe running from its nose, along its back to the top of its tail, while the sides, cheeks, throat, belly, and feet are whitish. There is a fairly sharp demarcation high on the sides between the dark upper and paler lower fur. The tail is bicolored like the body, darker above and whitish below. Juveniles are darker than adults, with a less sharply defined delineation between the dark and light fur. Adults have two annual moults. The exact timing of the spring moult is unknown, but it is probably complete by early June, and the autumn moult is complete by mid-October."
External measurements
Length measurements are in millimeters (mm) and weight measurements are in grams (g), unless stated otherwise. If available, the sample size (n=) is provided. If a range is not provided and n= is not given, then the listed measurement represents an average.
| Part of range | Reference | Total length | Tail length | Hindfoot length | Ear length | Mass |
|---|---|---|---|---|---|---|
| Canada | Naughton (2012) | 74–103 | 22–31 | 10.0–13.5 | 2.9–5.2 | |
| rangewide | Wilson & Ruff (editors, 1999) | 74–103 | 22–31 | 2.9–5.2 |
Skull
| Sorex ugyunak skull characters | |
|---|---|
| units in mm | |
| Skull | |
| Condylobasal length: | 13.7–15.2 (Northwest Territories; van Zyll de Jong, 1976); 14.78 (n=26; van Zyll de Jong, 1976); 15.1–16.0 (northern Alaska; Bee & Hall, 1956; use with caution) |
| Postmandibular canal: | Absent |
| Shape: | Braincase is rounded |
| Dental | |
| Upper unicuspids: | 5 |
| Unicuspid notes: | U3≥U4 |
| Tines present: | Yes |
| Tine size: | Medium |
| Tine position: | Below upper limit of pigment on upper incisors |
| Shape upper incisors: | Slightly diverging |
| Dental characters: | Tips of upper incisors are more widely separated partly because of tines |
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Dorsal view of the skull of Sorex ugyunak. -
Ventral view of the skull of Sorex ugyunak. Note that the right tympanic bone is missing. -
Lateral view of the skull of Sorex ugyunak. -
Upper unicuspids of Sorex ugyunak -
Upper incisors of Sorex ugyunak
Similar species
Sorex ugyunak is similar in appearance and may be confused with the Masked Shrew (Sorex cinereus). Externally, Sorex ugyunak can be differentiated from S. cinereus by its tricolored pelage and length of the tail. The skulls of S. ugyunak and S. cinereus are similar. However, in S. ugyunak the anterior position of infraorbital and lacrimal formina help distinguish this species from S. cinereus (Van Zyll de Jong, 1991).
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Sorex ugyunak. -
Masked Shrew (Sorex cinereus) from Denali Borough, Alaska.
References
Anderson RM, Rand AL. 1945. A new shrew from arctic North America. The Canadian Field-Naturalist 59(2): 62.
Hope AG, Speer KA, Demboski JR, Talbot SL, Cook JA. 2012. A climate for speciation: rapid spatial diversification within the Sorex cinereus complex of shrews. Molecular Phylogenetics and Evolution 64(3): 671-684.
Naughton D. 2012. The natural history of Canadian mammals. Toronto (ON, CA): University of Toronto Press.
Van Zyll de Jong CG. 1976. A comparison between woodland and tundra forms of the common shrew (Sorex cinereus). Canadian Journal of Zoology 54(6): pp.963-973.
Van Zyll de Jong CG. 1991. Speciation of the Sorex cinereus group. Pp. 65-73 in The biology of the Soricidae (J. S. Findley and T. L. Yates, eds.). Special Publication, Museum of Southwestern Biology 1:1-91.
Wilson DE, Ruff S, editors. 1999. The Smithsonian Book of North American Mammals. Washington D.C. (USA): Smithsonian Institution Scholarly Press.