Sorex bendirii
| Marsh Shrew
(Sorex bendirii) | |
|---|---|
| Range | |
 | |
| Taxonomic classification | |
| Order: | Eulipotyphla |
| Suborder: | Erinaceota |
| Family: | Soricidae |
| Subfamily: | Soricinae |
| Tribe: | Soricini |
| Genus: | Sorex |
| Subgenus: | Otisorex |
| Species group: | Sorex palustris group |
| Binomial details | |
| Sorex bendirii (Merriam, 1884) | |
| Other resources | |
| Full taxonomic details at MDD | |
Description
From Pattie (1973): "The only large, velvety, luscious-black shrew within its range, with underparts usually as dark as, or nearly so, as the upper parts and with a slight fringe of stiff hairs on the hind toes. On the Olympic Peninsula of Washington the underparts may be whitish."
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 |
|---|---|---|---|---|---|---|
| California | Jameson & Peeters (2004) | 145–170 | 60–80 | 18–21 | 7–9 | 16 |
| Canada | Naughton (2012) | 137–176 | 61–81 | 17–21 | 7–9 | 10.0–17.2 |
| Oregon (east slope of Cascade Range) | Verts & Carraway (1998) | 155 (n=1) | 71 (n=1) | 20 (n=1) | ||
| Oregon (west of Cascade Range) | Verts & Carraway (1998) | 143–181 | 59–81 | 19–23 | 11.2–23.9 | |
| rangewide | Wilson & Ruff (editors, 1999) | 128–174 | 58–80 | 7.5–21 | ||
Washington (except Olympic penninsula), Oregon (eastern half of range), California (except for northwest corner)
|
Pattie (1973) | 156 (n=15) | 70 (n=15) | 19.2 (n=15) | 8 (n=15) | 14.5 (n=15) |
| Washington (Olympic penninsula) | Pattie (1973) | 156 (n=22) | 67 (n=22) | 19.9 (n=22) | 7.8 (n=22) | 16.1 (n=22) |
Skull
| Sorex bendirii skull characters | |
|---|---|
| units in mm | |
| Skull | |
| Condylobasal length: | >19.3 (Pattie, 1973); 20.8–23.8 (Álvarez-Castañeda, 2024) |
| Postmandibular canal: | Absent |
| Shape: | Braincase only slightly rounded; rostrum shallow and distinctly downcurved |
| Dental | |
| Upper unicuspids: | 5 |
| Unicuspid notes: | U3<U4 |
| Tines present: | Yes |
| Tine size: | Medium |
| Shape upper incisors: | Slightly curved |
Diagnosis from Jameson & Peeters (2004): "Inner side of lower jaw without postmandibular canal; inner (median) surface of unicuspid teeth with pigmented ridge; third upper unicuspid smaller than fourth; first and second unicuspids equal or nearly equal; upper incisor with median tine or lobe."
From Verts & Carraway (1998): "Among Oregon shrews, S. bendirii is unique in having two posterolingually directed ridges on the occlusal surface of p4 and in having an anteroposterior length of c1 greater than that of p4 (Carraway, 1995)."
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Upper incisors of Sorex bendirii -
Unicuspids of Sorex bendirii, scale is 1 mm. Note that this is the skull of an older individual and the teeth are worn.
Similar species
This is a large uniformly black shrew (except for on the Olympic peninsula where the venter may be whitish) that is not easily confused with most of the other shrews in its range, which are much smaller and many of which are brown. The only species that it might be confused with is the Western Water Shrew (Sorex navigator), which is also a large, dark shrew (Pattie, 1973). S. navigator differs from S. bendirii in having a white venter and throat and hind feet that are bordered by a noticeable fringe of stiff hairs (Pattie, 1973). In S. bendirii, the tines on the medial edges of the upper incisors are more robust than in S. navigator.
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Ranges of Sorex bendirii and Sorex navigator. -
Upper incisors of Sorex bendirii. -
Upper incisors of Sorex navigator. Borrowed from Nagorsen et al. (2017).
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Unicuspids of Sorex bendirii, scale is 1 mm. Note that this is the skull of an older individual and the teeth are worn. -
Unicuspids of Sorex navigator, scale is 1 mm.
References
Carraway LN. 1995. A key to Recent Soricidae of the western United States and Canada based primarily on dentaries. University of Kansas.
Jameson EW, Peeters HJ. 2004. Mammals of California (No. 66). Berkeley (CA, USA): University of California Press.
Pattie D. 1973. Sorex bendirii. Mammalian Species (27): 1-2.
Merriam CH. 1884-08-28. Description of a new genus and species of the Sorecidae. (Atophyrax bendirii, with a plate). Transactions of the Linnean Society of New York 2:215-225.
Naughton D. 2012. The natural history of Canadian mammals. Toronto (ON, CA): University of Toronto Press.
Nagorsen DW, Panter N, Hope AG. 2017. Are the western water shrew (Sorex navigator) and American water shrew (Sorex palustris) morphologically distinct?. Canadian Journal of Zoology 95(10): 727-736.
Verts BJ, Carraway LN. 1998. Land mammals of Oregon. Berkeley (CA, USA): University of California Press.
Wilson DE, Ruff S, editors. 1999. The Smithsonian Book of North American Mammals. Washington D.C. (USA): Smithsonian Institution Scholarly Press.