Oryzomys palustris
| Northeastern Marsh Rice Rat
(Oryzomys palustris) | |
|---|---|
| Range | |
 | |
| Taxonomic classification | |
| Order: | Rodentia |
| Suborder: | Supramyomorpha |
| Infraorder: | Myomorphi |
| Superfamily: | Muroidea |
| Family: | Cricetidae |
| Subfamily: | Sigmodontinae |
| Tribe: | Oryzomyini |
| Genus: | Oryzomys |
| Binomial details | |
| Oryzomys palustris (Harlan, 1837) | |
| Other resources | |
| Full taxonomic details at MDD | |
The Northeastern Marsh Rice Rat (Oryzomys palustris) is a medium-sized rat that is typically found in marsh or grassland habitats.
Description
From Best & Hunt (2020): "The marsh oryzomys is a medium-sized rat. The coarse, moderately long pelage varies from grayish-brown to brown with scattered black and brown hairs on the dorsum. Pelage on the back is usually darker medially from neck to rump. Underparts and feet are white to grayish or tan. Front feet have four toes and hind feet have five toes. The tail is slender, nearly hairless, indistinctly bicolored, and about the same length as head and body combined. Eyes are dark and large, and ears are prominent. Small internal cheek pouches are present."
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 |
|---|---|---|---|---|---|---|
| Alabama | Best & Dusi (2014) | 232 (200–253) (n=25) | 114 (97–127) (n=25) | 31 (27–32) (n=25) | 15 (13–17) (n=25) | 58.2 (56.2–59.0) (n=2) |
| Carolinas, Virginia, Maryland | Webster et al. (1985) | 180–290 | 90–140 | 29–159 | ||
| Virginia | Linzey (1998) | 225–300 | 100–175 | 40–85 |
Skull
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Holotype: USNM 514995. Oryzomys palustris natator. Adult female. Cudjoe Key, Monroe County, Florida. Collected 8 February 1973. Dorsal view of the skull. -
Holotype: USNM 514995. Oryzomys palustris natator. Adult female. Cudjoe Key, Monroe County, Florida. Collected 8 February 1973. Ventral view of the skull. -
Holotype: USNM 514995. Oryzomys palustris natator. Adult female. Cudjoe Key, Monroe County, Florida. Collected 8 February 1973. Lateral view of the skull. -
Holotype: USNM 514995. Oryzomys palustris natator. Adult female. Cudjoe Key, Monroe County, Florida. Collected 8 February 1973. Dorsal view of the mandible. -
Holotype: USNM 514995. Oryzomys palustris natator. Adult female. Cudjoe Key, Monroe County, Florida. Collected 8 February 1973. Lateral view of the left mandible.
Similar species
Comparison with Oryzomys texensis
From Rose (2023): "The separation of the Texas marsh rice rat (Oryzomys texensis) from O. palustris was determined by differences at the molecular genetics level (Hanson et al. 2010) when the five subspecies of O. palustris were grouped into one clade and populations of the former subspecies texensis formed another clade. Although the skulls of O. palustris and O. texensis could be separated by such morphological features as breadth at the condyles and alveolar length of the upper and lower molar toothrows (Humphrey and Setzer 1989), few variables consistently separated these taxa."
Comparison with Rattus
From Rose (2023): "Members of the genus Rattus also are large and long-tailed but have relatively shorter, thicker, and hairless tails compared to the hairy and slim tail of O. palustris."
Comparison with Sigmodon hispidus
From Rose (2023): "The dorsum of the hispid cotton rat is brown compared with the grayish or buffy gray pelage of O. palustris. Its tail is relatively shorter and thicker than the long slender tail of O. palustris, plus it has blackish feet compared with the white feet of O. palustris. Maximum body mass of O. palustris is about 90 g compared to twice that for hispid cotton rats [Sigmodon hispidus].
References
Best TL, Dusi JL. 2014. Mammals of Alabama (Vol. 4). Tuscaloosa (AL, USA): University Alabama Press.
Best TL, Hunt JL. 2020. Mammals of the southeastern United States. Tuscaloosa (AL, USA): University Alabama Press.
Hanson JD, Indorf JL, Swier VJ, Bradley RD. 2010. Molecular divergence within the Oryzomys palustris complex: evidence for multiple species. Journal of Mammalogy 91(2):336-347.
Linzey DW. 1998. The mammals of Virginia. McDonald & Woodward Publishing.
Rose RK. 2023. Oryzomys palustris (Rodentia: Cricetidae). Mammalian Species 55(1031) p.sead006. https://doi.org/10.1093/mspecies/sead006
Webster WD, Parnell JF, Biggs WC. 1985. Mammals of the Carolinas, Virginia, and Maryland. Chapel Hill (NC, USA): University of North Carolina Press.