The montane fish-eating rat (''Neusticomys monticolus'') is a species of

semiaquatic In biology, semiaquatic can refer to various types of animals that spend part of their time in water, or plants that naturally grow partially submerged in water. Examples are given below. Semiaquatic animals Semiaquatic animals include: * Verte ...

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 ...

in the family

Cricetidae The Cricetidae are a family of rodents in the large and complex superfamily Muroidea. It includes true hamsters, voles, lemmings, muskrats, and New World rats and mice. At almost 608 species, it is the second-largest family of mammals, and has m ...

. It inhabits the

Andes Mountains The Andes, Andes Mountains or Andean Mountains (; ) are the List of mountain ranges#Mountain ranges by length, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range i ...

Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...

and

Ecuador Ecuador ( ; ; Quechua: ''Ikwayur''; Shuar: ''Ecuador'' or ''Ekuatur''), officially the Republic of Ecuador ( es, República del Ecuador, which literally translates as "Republic of the Equator"; Quechua: ''Ikwadur Ripuwlika''; Shuar: ''Eku ...

Description

Montane fish-eating rats are moderately sized rodents, with a head-body length of , a tail long, and a body weight averaging . Unlike all other fish-eating rats of the genus ''

Neusticomys ''Neusticomys'' is a genus of semiaquatic, animalivorous South American rodents in the family Cricetidae. The term ''Neusticomys'' derives from the two ancient greek words (), meaning "able to swim", and (), meaning "mouse, rat". ''N. monticol ...

'', it has dull greyish-black fur, consisting of a thick, velvety underfur and occasional dark

guard hair Guard hair or overhair is the outer layer of hair of most mammals, which overlay the fur. Guard hairs are long and coarse and protect the rest of the pelage (fur) from abrasion and frequently from moisture. They are visible on the surface of the fu ...

s. The fur is uniform over most of the body, and, unlike in many other rats, remains thick over the tail. However, the toes of all four feet are white, and some individuals have white spots on the upper body, the tip of the tail, or on the chest region. The ears are unusually large for a member of its

tribe The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide usage of the term in English language, English is in the discipline of anthropology. This definition is contested, in p ...

, and are visible above the thick fur. Like other ichthyomyine rodents, montane fish-eating rats have feet adapted for swimming in water. However, the adaptations are less extreme in this species than in most others; for example, the feet are narrower, and the fringe of stiff hairs around the toes is less well developed. A short web, not quite reaching the first joint, connects the second and third and the third and fourth toes. Females have six teats, one pair each on the chest, abdominal, and inguinal regions.

Distribution and habitat

Montane fish-eating rats are found only in the mountains of northern

and western

, where they inhabit fast moving streams flowing through

cloud forest A cloud forest, also called a water forest, primas forest, or tropical montane cloud forest (TMCF), is a generally tropical or subtropical, evergreen, montane, moist forest characterized by a persistent, frequent or seasonal low-level cloud c ...

s. They are found at elevations between . There are no recognised subspecies.

Diet and behaviour

Montane fish-eating rats are either

crepuscular In zoology, a crepuscular animal is one that is active primarily during the twilight period, being matutinal, vespertine, or both. This is distinguished from diurnal and nocturnal behavior, where an animal is active during the hours of daylig ...

nocturnal Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite. Nocturnal creatures generally have highly developed sens ...

. Despite their common name, they have never been observed to eat fish. Instead, the stomach contents of the few specimens examined consist solely of freshwater invertebrates, such as scirtid

water beetle A water beetle is a generalized name for any beetle that is adapted to living in water at any point in its life cycle. Most water beetles can only live in fresh water, with a few Marine (ocean), marine species that live in the intertidal zone or l ...

crane flies Crane fly is a common name referring to any member of the insect family Tipulidae. Cylindrotominae, Limoniinae, and Pediciinae have been ranked as subfamilies of Tipulidae by most authors, though occasionally elevated to family rank. In the most ...

mayflies Mayflies (also known as shadflies or fishflies in Canada and the upper Midwestern United States, as Canadian soldiers in the American Great Lakes region, and as up-winged flies in the United Kingdom) are aquatic insects belonging to the orde ...

stoneflies Plecoptera is an order of insects, commonly known as stoneflies. Some 3,500 species are described worldwide, with new species still being discovered. Stoneflies are found worldwide, except Antarctica. Stoneflies are believed to be one of the mo ...

, and

caddisflies The caddisflies, or order Trichoptera, are a group of insects with aquatic larvae and terrestrial adults. There are approximately 14,500 described species, most of which can be divided into the suborders Integripalpia and Annulipalpia on the b ...

. Little else is known of their habits and biology, because only 47 specimens have ever been collected. One of these specimens, collected in May, early in the wet season, was pregnant, but it is unknown whether or not there is a true breeding season.

References

*Musser, G. G. and M. D. Carleton. 2005. Superfamily Muroidea. pp. 894–1531 ''in'' Mammal Species of the World a Taxonomic and Geographic Reference. D. E. Wilson and D. M. Reeder eds. Johns Hopkins University Press, Baltimore. {{Taxonbar, from=Q1770077 Neusticomys Mammals of Colombia Mammals of the Andes Mammals described in 1921 Taxonomy articles created by Polbot