Sorex minutissimus
| Eurasian Least Shrew
(Sorex minutissimus) | |
|---|---|
| Range | |
 | |
| Taxonomic classification | |
| Order: | Eulipotyphla |
| Suborder: | Erinaceota |
| Family: | Soricidae |
| Subfamily: | Soricinae |
| Tribe: | Soricini |
| Genus: | Sorex |
| Subgenus: | Sorex (subgenus) |
| Species group: | Sorex araneus group |
| Binomial details | |
| Sorex minutissimus E. A. W. Zimmermann, 1780 | |
| Other resources | |
| Full taxonomic details at MDD | |
Sorex minutissimus is wide-ranging species, known to occur from Europe to the Yukon Territory in Canada. Hope et al. (2010) determined that Sorex yukonicus and Siberian Sorex minutissimus are conspecific (belonging to the same species). This page focuses on the distribution and important characters for identifying Sorex minutissimus in North America.
Description
From Dokuchaev (1997) describing Sorex minutissimus yukonicus: "The pelage is slightly tricolored with the dorsum being nearest fuscous, the flanks near hair gray, and the ventrum pale smoke gray (Ridgway, 1912). The tail is bicolored with the dorsal side being the same color as the dorsum, and the ventral side more white than the ventrum."
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 |
|---|---|---|---|---|---|---|
| Alaska (subspecies yukonicus) | Dokuchaev (1997) | head and body: 45.0–48.0 (n=5) | 23.0–27.0 (n=5) | 8.0–9.0 (n=5) | 1.5–1.7 (n=5) |
Skull
Postmandibular canal present. Five upper unicuspids are clearly visible in side view. The third unicuspid is slightly larger than the fourth.
| Sorex minutissimus skull characters | |
|---|---|
| units in mm | |
| Skull | |
| Condylobasal length: | 12.0–14.3 (Yudin, 1971) |
| Postmandibular canal: | Present |
| Dental | |
| Upper unicuspids: | 5 |
| Unicuspid notes: | U3>U4 |
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First specimen of Sorex minutissimus (MSB:Mamm:277743) from Canada showing (A) dorsal, (B) ventral, and (C) lateral views of the skull, as published in Cook et al. (2016). Scale bars = 5 mm.
Taxonomic notes
From Hope et al. (2010): "We found low genetic divergence between S. minutissimus and S. yukonicus across continents. However, major phylogeographic breaks were found for Eurasian and Maritime Northeast Asia populations. Neither species is reciprocally monophyletic for any of the loci examined. Coalescence times for all pairwise population comparisons within both species fall within the Wisconsinan–Weichselian glacial (<130 thousand years ago), and significant population expansion estimates date to the Holocene suggesting that divergence between these taxa is minimal and may not warrant recognition of 2 distinct species. Phylogeographic relationships and sequence divergence estimates place populations of North American S. yukonicus and Siberian S. minutissimus as most closely related, and together they are sister to European S. minutissimus. We conclude that populations east and west of the Bering Strait represent a single Holarctic species, S. minutissimus."
References
Cook JA, McLean BS, Jackson DJ, Colella JP, Greiman SE, Tkach VV, ... Dunnum JL. 2016. First record of the Holarctic least shrew (Sorex minutissimus) and associated helminths from Canada: new light on northern Pleistocene refugia. Canadian Journal of Zoology 94(5): 367-372.
Dokuchaev NE. 1997. A new species of shrew (Soricidae, Insectivora) from Alaska. Journal of Mammalogy 78(3):811-817.
Hope AG, Waltari E, Dokuchaev NE, Abramov S, Dupal T, Tsvetkova A, Henttonen H, MacDonald SO, Cook JA. 2010. High-latitude diversification within Eurasian least shrews and Alaska tiny shrews (Soricidae). Journal of Mammalogy 91(5): pp.1041-1057.
Ridgway R. 1912. Color standards and color nomenclature. R. Ridgway, Washington, D.C., 43 pp.
Yudin BS. 1971. [Insectivorous mammals of Siberia.] Nauka, Acad. Sci. USSR, Siberian Branch, Novosibirsk, 171 pp.
Zimmermann EAW. 1780. Geographische Geschichte des Menschen, und der allgemein verbreiteten vierfüßigen Thiere / von E. A. W. Zimmermann, Professor der Mathematik und Naturlehre am Kollegio Karolino zu Braunschweig ; 2. Band: Enthält ein vollständiges Verzeichniß aller bekannten Quadrupeden. Weygand, 385.