''Microryzomys'' is a genus of

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 n ...

in the tribe

Oryzomyini Oryzomyini is a tribe of rodents in the subfamily Sigmodontinae of the family Cricetidae. It includes about 120 species in about thirty genera,Weksler et al., 2006, table 1 distributed from the eastern United States to the southernmost parts of ...

of 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 h ...

. It is closely related to '' Oreoryzomys'', '' Oligoryzomys'', and ''

Neacomys The genus ''Neacomys'', also known as bristly mice because of their spiny fur, includes several species of rodents in the tribe Oryzomyini of family Cricetidae. It is most closely related to ''Oligoryzomys'', ''Oreoryzomys'', and ''Microryzomys'' ...

''.Weksler, 2006 It contains two species, both restricted to the

Andes The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...

: '' M. altissimus'' and '' M. minutus''.

Characteristics

''Microryzomys'' species are small members of the rodent tribe

, weighing in the region of , and characterised by their long soft fur and tail longer than their head-and-body-length. They have small hind feet with six fleshy pads on the under surface, and with the fifth toe nearly as long as the middle three. The four pairs of

mammae A mammary gland is an exocrine gland in humans and other mammals that produces milk to feed young offspring. Mammals get their name from the Latin word ''mamma'', "breast". The mammary glands are arranged in organs such as the breasts in primat ...

are arranged in the typical fashion for members of the tribe. At one time, this genus was considered to be a subgenus of ''

Oryzomys ''Oryzomys'' is a genus of semiaquatic rodents in the tribe Oryzomyini living in southern North America and far northern South America. It includes eight species, two of which—the marsh rice rat (''O. palustris'') of the United States and ...

'', but Carleton and Musser (1989) raised it to full generic status on the basis of various anatomic details of skull and dentition and on certain morphological traits.

Distribution

''Microryzomys'' is found in high mountainous areas of western South America. The range of the genus extends from the Caribbean coastal ranges and the

Cordillera de Mérida The Cordillera de Mérida is a series of mountain ranges, or massif, in northwestern Venezuela. The Cordillera de Mérida is a northeastern extension of the Andes Mountains and the most important branch of the Venezuelan Andes. The ranges run sou ...

of Venezuela, through the Cordillera Occidental, Cordillera Central and Cordillera Oriental of Colombia, to the Andes ranges of Ecuador, Peru and Bolivia. This is also the range of ''M. minutus'', because ''M. altissimus'' occurs only in the higher parts of this range and is limited to Colombia, Ecuador and Peru. ''M. minutus'' mostly occurs in moist forest habitats at altitudes between , while ''M. altissimus'' inhabits moist subalpine forests and páramo grassland, at altitudes between .

References

Literature cited

*Weksler, M. 2006
Phylogenetic relationships of oryzomyine rodents (Muroidea: Sigmodontinae): separate and combined analyses of morphological and molecular data
Bulletin of the American Museum of Natural History 296:1–149. {{Taxonbar, from=Q910103 Páramo fauna Rodent genera Taxa named by Oldfield Thomas Taxonomy articles created by Polbot