Phenacomys intermedius
| Western Heather Vole
(Phenacomys intermedius) | |
|---|---|
| Range | |
 | |
| Taxonomic classification | |
| Order: | Rodentia |
| Suborder: | Supramyomorpha |
| Infraorder: | Myomorphi |
| Superfamily: | Muroidea |
| Family: | Cricetidae |
| Subfamily: | Arvicolinae |
| Tribe: | Pliophenacomyini |
| Genus: | Phenacomys |
| Binomial details | |
| Phenacomys intermedius Merriam, 1889 | |
| Other resources | |
| Full taxonomic details at MDD | |
Description
From Armstrong et al. (2010): "The heather vole is a rather small vole with a tail only slightly longer than the hindfoot. The pelage is long and soft, almost shaggy, and dorsal color ranges from brown to grayish. The venter is silvery gray. The tail is bicolored, dark above and pale below, often with a sprinkling of white hairs over the dorsal surface. The feet are white to pale gray. Usually, there are stiff, orangish brown hairs in the ears."
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) | 130–153 | 26–41 | 16–18 | 13–16 | 21–40 |
| Colorado | Armstrong et al. (2010) | 130–140 | 31–34 | 16–19 | 13–17 | 30–50 |
| Minnesota | Hazard (1982) | 135–154 | 24–31 | 18–20 | 39.0–47 |
Color variation
This section shows some of the color variation present in Phenacomys intermedius. The location is provided for reference only. The individual shown does not necessarily represent the only color variant within the local population.
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Colorado, Boulder County -
juvenile, Colorado, Boulder County
Skull
From Armstrong et al. (2010): "The skull of adults is blocky with a square braincase and prominent supraorbital and lateral ridges. The palate does not end in a sharply transverse shelf as in Myodes (=Clethrionomys). The cheekteeth are rooted and without cusps, similar in general occlusal appearance to the teeth of other voles. However, the molars of the lower jaw have inner (lingual) reentrant angles that are much deeper than the outer (buccal) reentrant angles, extending more than halfway across the tooth surface. The first lower molar has a variable number (3 to 7) of closed occlusal triangles (McAllister and Hoffman 1988)."
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Lateral view of the skull of Phenacomys intermedius. -
Dorsal view of the skull of Phenacomys intermedius. -
Ventral view of the skull of Phenacomys intermedius. -
Dorsal view of the lower jaw of Phenacomys intermedius. -
The upper incisors of Phenacomys intermedius. -
Upper molars of Phenacomys intermedius. -
Lower molars of Phenacomys intermedius. Yellow arrow points to one of the many lingual re-entrant angles of lower cheek teeth, which are disproportionately large (more than halfway through the tooth; Naughton, 2012). The first lower molar (m1) has a variable number of closed triangles (3-7; Naughton, 2014). Black arrows point to the 5 closed triangles on the first lower molar (m1) in this individual.
Similar species
From Armstrong et al. (2010): "Superficially the heather vole may closely resemble some smaller individuals of the montane voles [Microtus montanus], from which is can be separated by the rooted cheekteeth with their deep inner reentrant angles."
Juveniles and subadults of Phenacomys intermedius may be confused with adults of Lemmiscus curtatus. Common habitats of Phenacomys intermedius include open coniferous forests with a shrubby understory, riparian areas with thickets, forest edges, and moist alpine and subalpine meadows. Common habitats of Lemmiscus curtatus include sagebrush and rabbitbrush mixed with bunchgrass.
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Phenacomys intermedius -
Phenacomys intermedius, subadult -
Montane Vole (Microtus montanus) -
Sagebrush Vole (Lemmiscus curtatus)
References
Armstrong DM, Fitzgerald JP, Meaney CA. 2010. Mammals of Colorado, Second Edition. Denver (CO, USA): University Press of Colorado.
Hazard EB. 1982. The mammals of Minnesota. Minneapolis (MN, USA): University of Minnesota Press.
Jameson EW, Peeters HJ. 2004. Mammals of California (No. 66). Berkeley (CA, USA): University of California Press.
Merriam CH. 1889. Description of a new genus Phenacomys and four new species of Arvicolinae. North American Fauna 2: 27-45.
McAllister JA, Hoffmann RS. 1988. Phenacomys intermedius. Mammalian Species (305): 1-8.