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Peromyscus keeni

From WhiskerWiki

Northwestern Deermouse
(Peromyscus keeni)
Range
Taxonomic classification
Order:Rodentia
Suborder:Supramyomorpha
Infraorder:Myomorphi
Superfamily:Muroidea
Family:Cricetidae
Subfamily:Neotominae
Tribe:Peromyscini
Genus:Peromyscus
Binomial details
Peromyscus keeni (Rhoads, 1894)

Description

From Naughton (2012) for Canada: "Fur colour and body size vary considerably across the range, and this mouse is inclined toward gigantism in isolated island populations. Generally, the dorsal fur is brown, reddish-brown, or dark grey-brown with a darker brown band of colour running along the spine from the head to the rump, but some island populations are dark brown with a blackish dorsal dorsal band. Belly and chest hairs are mostly white or pale grey at their tips with dark grey roots, but some island populations have buffy to reddish-brown tips on their belly and chest fur. Some animals have a small patch of hairs under their chin that are white all the way to the root. Hairs on the upper surface of the front feet are white, but on the same part of the hind feet the fur may be white, pale silvery grey, or dark brown or even partially dark brown with white toes on a few animals. The large eyes are black, bulging, and luminous. Vibrissae are long and constantly in motion when the mouse is active. Ears are long and mostly covered with a thin layer of fine, very short, dark hairs. The long tail is sharply bicoloured, dark brown above and white below, with a tuft of stiff hairs at the tip that are 4–5 mm in length. Juveniles undergo two maturational moults before achieving their adult pelage, after which they moult once annually in late summer. Juveniles are usually dark grey above and grey to silver-grey below, while subadults are dark brown above and silver-grey to white below."

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) 140–263 70–126 19–32 12–26 15.0–52.4


Color variation

This section shows some of the color variation present in Peromyscus keeni. The location is provided for reference only. The individual shown does not necessarily represent the only color variant within the local population.

Skull

  • Dorsal view of the skull of Peromyscus keeni.
  • Lateral view of the skull of Peromyscus keeni. Lower mandible not shown.
  • Ventral view of the skull of Peromyscus keeni.
  • Upper incisors of Peromyscus keeni.
  • Dorsal view of the lower mandible of Peromyscus keeni.

Similar species

Comparison with Peromyscus sonoriensis

From Naughton (2012): "While chromosomally distinct from Deer Mice [Peromyscus maniculatus (sensu lato)], there are, unfortunately, no completely reliable physical traits that will distinguish all Keen's Mice from Deer Mice in the field... The following formula using diastema length (the gap between the back of the incisors and front edge of the molars) and tail length separates the two species in the southern part of their range, including Washington State and Vancouver Island and the surrounding islands: 4.4 x length of tail (in mm) + length of mandibular diastema (in mm). Animals with a score of ≥ 436 are Keen's Mice, while those with scores of < 436 are Deer Mice. The efficacy of this formula, when applied to inland and more northerly populations has not yet been assessed, and the formula is ineffective in identifying living animals."

References

Hogan KM, Hedin MC, Koh HS, Davis SK, Greenbaum IF. 1993. Systematic and taxonomic implications of karyotypic, electrophoretic, and mitochondrial-DNA variation in Peromyscus from the Pacific Northwest. Journal of Mammalogy 74(4): 819-831.

Naughton D. 2012. The natural history of Canadian mammals. Toronto (ON, CA): University of Toronto Press.

Rhoads SN. 1894. Descriptions of four new species and two subspecies of White-footed mice from the United States and British Columbia. Proceedings of the Academy of Natural Sciences of Philadelphia 46, 258.

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