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Sigmodon arizonae

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Arizona Cotton Rat
(Sigmodon arizonae)
Range
Taxonomic classification
Order:Rodentia
Suborder:Supramyomorpha
Infraorder:Myomorphi
Superfamily:Muroidea
Family:Cricetidae
Subfamily:Sigmodontinae
Tribe:Sigmodontini
Genus:Sigmodon
Subgenus:Sigmodon (subgenus)
Binomial details
Sigmodon arizonae Mearns, 1890

Description

From Hoffmeister (1986): "A Sigmodon of large size; hind foot usually 32.0 mm or longer; tail usually 110 mm or longer; dorsal pelage silvery or whittish with base of hairs blackish; underside of tail nearly same color as venter; tops of feet silvery gray."

From Gwinn et al. (2011): "Sigmodon arizonae has a hispid, light brownish black dorsal pelage and light silver or whitish underparts with hairs having a blackish base. The feet are covered in grayish to dull brown-colored hair dorsally and tend to blend with the dorsal pelage. The tail is dark dorsally and grades into lighter brown or silvery on the underside. The tail has large, coarse caudal "scales" and is sparsely covered with long caudal hairs (Carleton et al. 1999; Hoffmeister 1986)."

Sigmodon arizonae photographed in Gilbert, Arizona. Image by Gordon Karre.

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
Arizona (Camp Verde) Hoffmeister (1986) males: 304–349 (n=7); females: 276–346 (n=5) males: 116–156 (n=7); females: 116–151 (n=5) males: 34–40 (n=7); females: 33–38 (n=5)
Arizona (Maricopa Co. [central]) Hoffmeister (1986) males: 240–300 (n=22); females: 198–291 (n=17) males: 92–139 (n=22); females: 85–122 (n=17) males: 32–38 (n=22); females: 28–35 (n=17) males: 19–23 (n=22); females: 18–22 (n=17)
Arizona (Pima and Santa Cruz cos.) Hoffmeister (1986) males: 222–325 (n=49); females: 212–292 (n=31) males: 94–137 (n=49); females: 92–132 (n=31) males: 29–38 (n=49); females: 30–35 (n=31) males: 18–23 (n=49); females: 18–21 (n=31)
Arizona (Yuma Co. [northern]) Hoffmeister (1986) males: 277–321 (n=4); females: 266–304 (n=4) males: 124–135 (n=4); females: 122–145 (n=4) males: 35–37 (n=4); females: 35–36 (n=4) males: 19–24 (n=4); females: 20–22 (n=4)
not reported Carleton et al. (1999) 18–24 (n=127) 83.0–300.0 (n=19)
not reported Ceballos (editor, 2014) 231–345 95–155 34–42 17–24 140–200
not reported Gwinn et al. (2011) 247.0–363.0 (n=154) 101.0–145.0 (n=154) 34.0–43.0 (n=158)


Similar species

From Gwinn et al. (2011): S. arizonae differs from "S. fulviventer (tawny-bellied cotton rat) in both cranial morphology and the absence of the tawny-colored dorsal pelage present in S. fulviventer (Baker and Shump 1978a; Hoffmeister 1986); ochrognathus (yellow-nosed cotton rat) by differing cranial morphology and the lack of yellowish fur around its nose (Baker and Shump 1978b; Hoffmeister 1986)."

Skull measurements

From Hoffmeister (1986): "skull large; distance between parietal and squamosal crests 3.2 mm or greater; length of squamosal crest usually 7.0 mm or longer; anterior spine on infraorbital plate pointed and narrow; dorsal border of occipital shield smoothly curved; palatine foramina tapered posteriorly; anteroventral border of foramen magnum angular."

References

Baker RH, Shump Jr. KA. 1978a. Sigmodon fulviventer. Mammalian Species 94:1-4.

Baker RH, Shump Jr. KA. 1978b. Sigmodon ochrognathus. Mammalian Species 97:1-2.

Carleton MD, Fisher RD, Gardner AL. 1999. Identification and distribution of cotton rats, genus Sigmodon. Proceedings of the Biological Society of Washington 112:813-856.

Ceballos G, editor. 2014. Mammals of Mexico. Baltimore (MD, USA): Johns Hopkins University Press.

Gwinn RN, Palmer GH, Koprowski JL. 2011. Sigmodon arizonae (Rodentia: Cricetidae). Mammalian Species 43(883): 149-154.

Hoffmeister DF. 1986. Mammals of Arizona. Tucson (AZ, USA): University of Arizona Press.

Mearns EA. 1890. Description of supposed new species and subspecies of mammals, from Arizona. Bulletin of the American Museum of Natural History 2, 287.

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