The cursor grass mouse or cursorial akodont (''Akodon cursor''), is a sigmodontine

rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), 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 roden ...

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 souther ...

Description

The cursor grass mouse is a moderately sized rodent, with a head-body length of , and a tail long. Males are larger than females, weighing an average of , compared with for females. They have a typical mouse-like appearance, with short whiskers and stubby claws on the feet. They have dark to golden brown fur over most of their body, with paler greyish or yellowish underparts. Some have a whitish spot between the ears, but this is not present on all individuals. Cursor grass mice are members of the ''A. cursor''

species group In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

, and very similar in appearance to other members of the group. In particular, they cannot easily be distinguished from the closely related montane grass mouse, which inhabits neighbouring regions to the immediate south. Although the cursor grass mouse is, on average, slightly larger than the montane species, there is too much overlap for this to be a reliable guide. Instead, they can most readily be distinguished by the presence of a

gall bladder In vertebrates, the gallbladder, also known as the cholecyst, is a small hollow organ where bile is stored and concentrated before it is released into the small intestine. In humans, the pear-shaped gallbladder lies beneath the liver, althoug ...

in ''A. cursor'' (absent in the montane species), by karyotypic analysis, or by means of PCR based techniques.

Distribution and habitat

The exact geographic range of the cursor grass mouse is disputed. It is definitively known to inhabit eastern

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

from Paraiba to Paraná, where it lives in patches of tropical

Atlantic Forest The Atlantic Forest ( pt, Mata Atlântica) is a South American forest that extends along the Atlantic coast of Brazil from Rio Grande do Norte state in the northeast to Rio Grande do Sul state in the south and inland as far as Paraguay and t ...

and

restinga Restingas () are a distinct type of coastal tropical and subtropical moist broadleaf forest in eastern Brazil. They form on sandy, acidic, and nutrient-poor soils, and are characterized by medium-sized trees and shrubs adapted to the drier and nut ...

scrubland at elevations from sea level to . Some sources also report it as being found further south, in extreme southern Brazil, in eastern

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 ...

, and in northern

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, t ...

. These latter sources lack a definitive genetic analysis of the individuals identified, and it has been argued that they may represent members of other species, such as the montane grass mouse. No subspecies are recognised.

Biology and behaviour

Cursor grass mice are omnivorous. Their primary diet consists of small arthropods, especially Hymenoptera,

beetle 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 ...

s, and

spider Spiders (order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species d ...

s; this is supplemented by seeds of ''

Cecropia ''Cecropia'' is a Neotropical genus consisting of 61 recognized species with a highly distinctive lineage of dioecious trees. The genus consists of pioneer trees in the more or less humid parts of the Neotropics, with the majority of the speci ...

'' and other plants. They search for food through leaf litter and patches of dense vegetation, and are strictly terrestrial. Individuals have a

home range A home range is the area in which an animal lives and moves on a periodic basis. It is related to the concept of an animal's territory which is the area that is actively defended. The concept of a home range was introduced by W. H. Burt in 1943. H ...

of , with the ranges of males being larger than those of females. Although the size of their home ranges does not change, the population density of cursor grass mice becomes significantly higher during the rainy season, when insects are most abundant. Cursor grass mice breed throughout the year, although most births occur during the dry season between June and September. Pregnant females construct globular nests, and give birth to a litter of two to nine young, with an average of four, after a

gestation Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during preg ...

period of 23 days. This species is particularly important for public health since it has been implied as a Hantavirus reservoir. A cell line derived from a

liposarcoma Liposarcomas are the most common subtype of soft tissue sarcomas, accounting for at least 20% of all sarcomas in adults. Soft tissue sarcomas are rare neoplasms with over 150 different histological subtypes or forms. Liposarcomas arise from the ...

in a cursor grass mouse has been used by biomedical scientists in the construction of a panel for the identification of human

chromosome A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins ar ...

s in hybrid cells.

References

{{Taxonbar, from=Q306995 Akodon Mammals described in 1888 Taxa named by Herluf Winge