Aquatic rat

Anotomys leander is the only member of its genus, which belongs the tribe Ichthyomyini, subfamily Sigmodontinae and family Cricetidae.[3][2] The ichthyomyines are semiaquatic carnivorous rodents that are found in South America from Mexico to Peru.[5]

A. leander has a very small range, the smallest range of the ichthyomyines.[6] Very few specimens have been captured so the full extent of its habitat and range is not completely known; the range is estimated at 40 km² (15 sq mi).[1] The species is found in northern Ecuador along the Andes mountains; however, it has also been found at a single locality in Colombia. Individuals have only been found at elevations of 2,800 to 4,000 m (9,200 to 13,100 ft).[4] Their habitat is primarily wetlands that have streams, but also includes grassy paramo and mossy elfin forest edge.[1] Every known specimen has been found near running water.

The aquatic rat possess several distinctive characteristics, many of which can also be found in closely related ichthyomyines. The length of the tail is greater than the length of the body, and they have very large hind feet. They also have reduced or absent pinnae covered by a tuft of white fur.[4] These characteristics are believed to aid in aquatic hunting and movement. For hunting the rodents rely on their vibrissae (whiskers) to help locate prey along the streams edge. The vibrissae contain a very sensitive and developed trigeminal nerve that runs along the infraorbital foramen.[4]

The species is listed as endangered and is threatened by pollution and habitat loss.[1] Their small range makes them vulnerable to habitat loss. Because they rely on a partially aquatic habitat, water pollution, such as oil spills, also poses a serious threat.[1]