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Sorex

From WhiskerWiki

Genus Sorex
Taxonomic classification
Order:Eulipotyphla
Suborder:Erinaceota
Family:Soricidae
Subfamily:Soricinae
Tribe:Soricini

Sorex is a genus of small, long-tailed shrews found in North America and Eurasia. As with all members of the subfamily Soricinae, Sorex have red-tipped teeth. The enamel of the tips of their teeth is reddish due to iron pigment, which serves to harden the enamel. Externally, they have somewhat long, pointed noses, tiny eyes and small ears that are often hidden by their fur.

Species in the United States

Species not pictured: Eastern Water Shrew (Sorex albibarbis), Arizona Shrew (Sorex arizonae), Saint Lawrence Island Shrew (Sorex jacksoni), Pribilof Island Shrew (Sorex pribilofensis).

Available taxon pages

The following subgenera are available on WhiskerWiki for this genus:


Range maps for species in the United States

Skull comparison

Accurate identification of shrews typically requires careful examination of the skull. Below is a table of skull characters that are most useful for identification.

Species Number unicuspids Postmandibular canal Unicuspid notes Tines upper incisors Tine size Tine position Shape medial edge incisors Skull shape Dental characters Condylobasal length
Sorex albibarbis 5 Absent U3<U4 Yes Small 19.1–21.7 (Beneski & Stinson, 1987); 18.4–19.2 (Álvarez-Castañeda, 2024)
Sorex arcticus 5 Present U3≥U4 Yes Small Well below upper limit of pigment on upper incisors Straight Skull relatively flat; braincase slightly rounded Unicuspids robust and appear bulbous in ventral view; tips of upper incisors are more widely separated partly because of tines 19.1–20.0 (Kirkland & Schmidt, 1996)
Sorex arizonae 5 Present U3≥U4 Yes Medium Well below upper limit of pigment on upper incisors Straight Braincase is slightly rounded (based on image from Diersing & Hoffmeister, 1977) Tips of upper incisors are more widely separated partly because of tines (Diersing & Hoffmeister, 1977) 15.7–16.53 (Diersing & Hoffmeister, 1977); 15.7–16.53 (Álvarez-Castañeda, 2024)
Sorex bendirii 5 Absent U3<U4 Yes Medium Slightly curved Braincase only slightly rounded; rostrum shallow and distinctly downcurved >19.3 (Pattie, 1973); 20.8–23.8 (Álvarez-Castañeda, 2024)
Sorex cinereus 5 Absent U3≥U4; U1–U4 are in an almost graduated series Yes Medium Well below upper limit of pigment on upper incisors Parallel or slightly diverging Rounded braincase Tips of upper incisors are more widely separated partly because of tines 14.3–16.1 (French, 1980); 14.6–16.9 (Álvarez-Castañeda, 2024)
Sorex dispar 5 Absent U3≥U4 Yes Tiny At or just below the upper limit of pigment on upper incisors Diverging Rostrum shallow; braincase bulbous; posterior border of the infraorbital foramen behind the space between the M1 and M2; mental foramen level with the space between p4 and m1 15.8–18.5 (Hall & Kelson, 1959); 16.45–18.7 (Kirkland, 1981); 15.35–18.7 (S. d. gaspensis; Kirkland, 1981); 18.4–19.2 (Álvarez-Castañeda, 2024)
Sorex eximius 5 Absent U3 and U5 are tiny and vestigial Yes Large and long Well below upper limit of pigment on upper incisors Slightly curved Skull relatively flat; braincase slightly rounded U3 and U5 are barely or not at all visible in side view, but may be seen in occlusal view 13.0–15.8 (Hall & Kelson, 1959); 15.0–16.2 (Álvarez-Castañeda, 2024)
Sorex fontinalis 5 Absent U3≥U4 Yes Small Just below the upper limit of pigment on upper incisors Diverging Skull relatively flat 14.63–15.85 (Kirkland & Levengood, 1987); 14.6–15.2 (Junge & Hoffman, 1981)
Sorex fumeus 5 Absent; occasionally present on one side U3>U4 Yes Small Just below the upper limit of pigment on upper incisors Strongly curved and diverging Braincase flattened, sometimes extremely; posterior border of the infraorbital foramen ahead of the space between the M1 and M2; mental foramen approximately level with the protoconid of m1 Width of unicuspids exceeds length 17.4–18.5 (Owen, 1984)
Sorex haydeni 5 Absent U3≥U4 Yes NA 14.2–15.1 (n=10; van Zyll de Jong, 1976); 15.0–16.1 (French, 1980); 14.1–15.9 (Álvarez-Castañeda, 2024)
Sorex hoyi 5 Absent U3 and U5 are tiny and vestigial Yes Large and long Well below upper limit of pigment on upper incisors Slightly curved Braincase is rounded U3 and U5 are barely or not at all visible in side view, but may be seen in occlusal view 13.0–15.8 (Hall & Kelson, 1959); 14.3–15.0 (Álvarez-Castañeda, 2024)
Sorex jacksoni 5 Absent U3≥U4 Yes NA 15.6–16.3 (Hall & Kelson, 1959)
Sorex longirostris 5 Absent U3<U4; U3 and U4 sometimes subequal Yes Small At or just below pigment line Strongly diverging Braincase is rounded 13.8–15.6, except S. l. fisheri 15.4–16.4 (French, 1980)
Sorex lyelli 5 Absent U3≥U4 Yes NA 15.2–15.4 (Hall & Kelson, 1959)
Sorex merriami 5 Present U3>U4; U2 is largest No NA Converging Braincase relatively flat Tips of upper incisors are close together since teeth converge distally 15.7–17.1 (Armstrong & Jones, 1971), 16–18 (Armstrong, 2010); 15.1–16.9 (Álvarez-Castañeda, 2024)
Sorex minutissimus 5 Present U3>U4 NA 12.0–14.3 (Yudin, 1971)
Sorex monticolus 5 Absent U3<U4 Yes Small-medium Below upper limit of pigment on upper incisors Diverging Braincase is rounded 16.1–17.7 (Hennings & Hoffman, 1977); 16.1–19.2 (Junge & Hoffman, 1981) ; 16.2–16.7 (Álvarez-Castañeda, 2024)
Sorex nanus 5 Absent U3<U4 Yes Medium Below upper limit of pigment on upper incisors Diverging Braincase narrow and appears flattened when viewed from the side A diagnostic dental measurement is the distance from the posterior border of the alveolus of the fifth unicuspid to the anterior margin of the alveolus of the incisor ranges between 1.8 and 2.4 mm. 13.8–14.8 (Hoffman & Owen, 1980)
Sorex navigator 5 Absent U3<U4; U2>U1 Yes; although lacking in some individuals Tiny Well below upper limit of pigment on upper incisors Diverging 19.1–21.7 (Beneski & Stinson, 1987); up to 22 (Armstrong, 2010)
Sorex obscurus 5 Absent U3<U4 Yes Small-medium Below upper limit of pigment on upper incisors Diverging Skull somewhat slightly flattened 16.1–17.7 (Hennings & Hoffman, 1977); 16.1–19.2 (Junge & Hoffman, 1981)
Sorex ornatus 5 Absent U3<U4 Yes Medium Below upper limit of pigment on upper incisors Diverging Relatively flat and broad and depressed interorbitally Upper toothrow not crowded, with distinct triangular space between postero-medial edge of the fifth unicuspid and antero-medial edge of premolar; tips of upper incisors are more widely separated partl… 14.7–17.1 (Owen & Hoffman, 1983); 15.6–17.1 (Álvarez-Castañeda, 2024)
Sorex pacificus 5 Absent U3<U4 No; but may have a median ridge NA Slightly diverging (based on illustration in Carraway, 1985) In ventral view, the unicuspids are wider than long 19.0–22.8 (Junge & Hoffman, 1981); 21.4–23.0 (Álvarez-Castañeda, 2024)
Sorex palustris 5 Absent U3<U4 Yes Small Below upper limit of pigment on upper incisors Diverging Rostrum straight or downcurved only slightly; braincase broad and flattened 19.1–21.7 (Beneski & Stinson, 1987)
Sorex preblei 5 Absent U3>U4; U1–U4 are in an almost graduated series Yes Long~~acutely pointed Below upper limit of pigment on upper incisors Diverging Skull relatively flat 13.8–14.6 (Hoffman et al., 1969); less than or equal to 14.8 (Carraway, 1998); 13.8–15.1 (Álvarez-Castañeda, 2024)
Sorex pribilofensis 5 Absent U3>U4 NA 15.4–16.0 (Hall & Kelson, 1959)
Sorex rohweri 5 Present U3<U4 Yes Tiny At or above the upper pigment edge Diverging; slightly curved Tines are are weak and often difficult to discern; pigmentation is pale or lacking (Woodman & Fisher, 2016) 14.7–16.6 (Woodman & Fisher 2016)
Sorex sonomae 5 Absent U3<U4; U5 usually rectangular No NA Parallel Braincase is rounded Unicuspids appear somewhat bulbous; fifth unicuspid is usually rectangular and is separated from the fourth premolar by a gap (Verts & Carrawy, 1998) S. s. sonomae: 19.34–23.22 (Carraway, 1989); S. s. tenelliodus: 16.5–20.21 (Carraway, 1989)
Sorex tenellus 5 Absent U3<U4 Yes Tiny Below upper limit of pigment on upper incisors Diverging Braincase is slightly rounded (based on images) 14.5–15.3 (Hoffman & Owen, 1980)
Sorex trowbridgii 5 Present U3<U4 Yes Small-medium Below upper limit of pigment on upper incisors Diverging and curved Braincase is rounded 16.8–18.8 (see George, 1989 for citations); 16.8–17.5 (Álvarez-Castañeda, 2024)
Sorex tundrensis 5 Present U3>U4 Yes Medium Well below upper limit of pigment on upper incisors Parallel or slightly diverging Braincase is slightly rounded 17.0–18.5 (Junge & Hoffman, 1981)
Sorex ugyunak 5 Absent U3≥U4 Yes Medium Below upper limit of pigment on upper incisors Slightly diverging Braincase is rounded Tips of upper incisors are more widely separated partly because of tines 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)
Sorex vagrans 5 Absent; occasionally present on one side U3<U4 Yes Small At or above the upper edge of pigment; commonly there is a white or pale-colored area between the tine and body of the tooth Diverging Braincase is rounded 15.5–17.5 (Gillihan & Foresman, 2004)

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