The Argentine swamp rat (''Scapteromys aquaticus'') is a semiaquatic

rodent Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are na ...

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

from

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

. It is found in northeastern

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

and

Paraguay Paraguay (; ), officially the Republic of Paraguay ( es, República del Paraguay, links=no; gn, Tavakuairetã Paraguái, links=si), is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to th ...

, where it lives in freshwater marshes and along the southern coast of the Río de la Plata estuary, as well as in woodland. It is characterized by having stiff hairs on its otherwise naked tail, which are believed to help the animal swim. ''S. aquaticus'' is similar in build to members of the genus ''

Rattus ''Rattus'' is a genus of muroid rodents, all typically called rats. However, the term rat can also be applied to rodent species outside of this genus. Species and description The best-known ''Rattus'' species are the black rat (''R. rattus'') ...

''. “ thas a relatively larger head, a stouter body, larger feet, and a relatively longer tail.” The pelage along its back is “long and glossy” varying from brown to dark brown. It can have a grayish wash in some individuals. “The sides have a yellowish cast.” The pelage in the abdominal region is typically an off white color. The forefeet are large for use in swimming and digging. All digits, including the pollex are equipped with a claw. Its

karyotype A karyotype is the general appearance of the complete set of metaphase chromosomes in the cells of a species or in an individual organism, mainly including their sizes, numbers, and shapes. Karyotyping is the process by which a karyotype is disce ...

has 2n = 32.

Conservation

According to the IUCN Red List of Threatened Species in 2008 the Argentine swamp rat was classified as

least concern A least-concern species is a species that has been categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. T ...

because of “its wide distribution, presumed large

population Population typically refers to the number of people in a single area, whether it be a city or town, region, country, continent, or the world. Governments typically quantify the size of the resident population within their jurisdiction using a ...

, and because it is unlikely to be declining at nearly the rate required to qualify for listing in a

threatened Threatened species are any species (including animals, plants and fungi) which are vulnerable to endangerment in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of ''critical depensat ...

category.”

Habitat

These rodents are found in low, flooded grasslands, salt marshes and any area with standing water. They are good swimmers and employ the aid of their “swimming fringe” and have also been observed diving.

Distribution

Argentine swamp rats are found scattered through the Rio de la Plata basin and other areas in east-central Argentina, south coastal Brazil, southern Paraguay, and Uruguay.

Biology and behavior

Argentine swamp rats eat mostly

beetles Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...

and

earthworms An earthworm is a terrestrial invertebrate that belongs to the phylum Annelida. They exhibit a tube-within-a-tube body plan; they are externally segmented with corresponding internal segmentation; and they usually have setae on all segments. Th ...

. They are active during both day and night. Females were found, on average, with between three and five young and breeding males were found year-round. There is no evidence that they dig

burrow An Eastern chipmunk at the entrance of its burrow A burrow is a hole or tunnel excavated into the ground by an animal to construct a space suitable for habitation or temporary refuge, or as a byproduct of locomotion. Burrows provide a form of sh ...

s. Researchers have discovered young in shallow depressions in the ground covered by matted grass.

References

* {{DEFAULTSORT:Argentine swamp rat Mammals of Argentina Scapteromys Mammals described in 1920 Taxa named by Oldfield Thomas