Sigmodon arizonae
| Arizona Cotton Rat
(Sigmodon arizonae) | |
|---|---|
| Range | |
 | |
| Taxonomic classification | |
| Order: | Rodentia |
| Suborder: | Supramyomorpha |
| Infraorder: | Myomorphi |
| Superfamily: | Muroidea |
| Family: | Cricetidae |
| Subfamily: | Sigmodontinae |
| Tribe: | Sigmodontini |
| Genus: | Sigmodon |
| Binomial details | |
| Sigmodon arizonae Mearns, 1890 | |
| Other resources | |
| Full taxonomic details at MDD | |
The Arizona Cotton Rat (Sigmodon arizonae) is cotton rat found in Arizona, New Mexico, and in the northwestern part of Mexico. It is a desert species, occupying areas with mesquite and a small amount of grasses or in areas along canals and streams with sufficient vegetative cover (Hoffmeister, 1986).
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)."
Museum specimens
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Holotype: AMNH MO-1841, AMNH MS-2370. Sigmodon arizonae. Male. Fort Verde, Yavapai County, Arizona. Collected 18 Septemeber 1885. Dorsal view. -
Holotype: AMNH MO-1841, AMNH MS-2370. Sigmodon arizonae. Male. Fort Verde, Yavapai County, Arizona. Collected 18 Septemeber 1885. Ventral view. -
Holotype: USNM 181086. Sigmodon arizonae plenus. Adult male. Parker, La Paz County, Arizona. Collected 2 February 1913. -
Holotype: USNM 181086. Sigmodon arizonae plenus. Adult male. Parker, La Paz County, Arizona. Collected 2 February 1913.
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) |
Skull
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."
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Holotype: USNM 181086. Sigmodon arizonae plenus. Adult male. Parker, La Paz County, Arizona. Collected 2 February 1913. Dorsal view of the skull. -
Holotype: USNM 181086. Sigmodon arizonae plenus. Adult male. Parker, La Paz County, Arizona. Collected 2 February 1913. Ventral view of the skull. -
Holotype: USNM 181086. Sigmodon arizonae plenus. Adult male. Parker, La Paz County, Arizona. Collected 2 February 1913. Lateral view of the skull. -
Holotype: USNM 181086. Sigmodon arizonae plenus. Adult male. Parker, La Paz County, Arizona. Collected 2 February 1913. Dorsal view of the mandible. -
Holotype: USNM 96275. Sigmodon arizonae major. Adult male. Sierra de Choix, Sinaloa, Mexico. Collected 20 October 1898. Lateral view of the left mandible. -
Holotype: USNM 181086. Sigmodon arizonae plenus. Adult. Upper molars. -
Holotype: USNM 181086. Sigmodon arizonae plenus. Adult. Lower molars.
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)." Sigmodon hispidus and Sigmodon arizonae look superficially similar but their ranges are mostly non-overlapping.
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Arizona Cotton Rat (Sigmodon arizonae) photographed by Gordon Karre in Gilbert, Arizona. -
Tawny-bellied Cotton Rat (Sigmodon fulviventer) observed by Ricardo Arredondo T. in Coeneo, Michoacán, México. -
Yellow-nosed Cotton Rat (Sigmodon ochrognathus) observed by Randy Babb. Sigmodon ochrognathus has a conspicuous "yellow" nose. -
Hispid Cotton Rat (Sigmodon hispidus) observed by Bob Oswald in Gainesville, Florida. Sigmodon hispidus and Sigmodon arizonae look superficially similar but their ranges are mostly non-overlapping.
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. https://doi.org/10.1644/883.1
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.