The toros or brush-tailed rats, genus Isothrix, are a group of spiny rat

Spiny rat

The spiny rats are a group of hystricognath rodents in the family Echimyidae. They are distributed from central Central America through much of South America. They were also found in the West Indies until the 19th century...

s found in tropical South America

South America

South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

, particularly in the Amazon Basin

Amazon Basin

The Amazon Basin is the part of South America drained by the Amazon River and its tributaries that drains an area of about , or roughly 40 percent of South America. The basin is located in the countries of Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru, and Venezuela...

.

Description

Toros look like large rat

Rat

Rats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, Rattus norvegicus...

s with soft fur on the body and long guard hair

Guard hair

Guard hairs are the longest, coarsest hairs in a mammal's coat, forming the topcoat . They taper to a point and protect the undercoat from the elements. They are often water repellent and stick out above the rest of the coat...

s on the scaly tail (Emmons, 2005). Head and body is 18-27.5 cm and tail is 17–30 cm (Nowak, 1999). Weight is 320-570 grams.

Natural history

These animals appear to be arboreal, based on the shape of their hind feet (Nowak, 1999). They are thought to spend the day in holes in the ground near trees.

Classification

There are currently five species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 recognized in the genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

. Callistomys pictus was previously considered a member of this genus, but most authors consider it distinct enough to warrant a separate genus (Woods and Kilpatrick, 2005). Although tentatively considered an echimyine, Emmons (2005) and other authors as have suggested that Isothrix may not be particularly closely related to other members of its subfamily. There does, however, appear to be good support for the monophyly

Monophyly

In common cladistic usage, a monophyletic group is a taxon which forms a clade, meaning that it contains all the descendants of the possibly hypothetical closest common ancestor of the members of the group. The term is synonymous with the uncommon term holophyly...

 of the three species found in this genus (Emmons, 2005).

Species

• Genus Isothrix
  • Isothrix bistriata - Yellow-crowned Brush-tailed Rat
  • Isothrix negrensis - Rio Negro Brush-tailed Rat
  • Isothrix pagurus - Plain Brush-tailed Rat
  • Isothrix sinnamariensis - Sinnamary Brush-tailed Rat
  • Isothrix barbarabrownae
    Isothrix barbarabrownae
    Isothrix barbarabrownae is a recently discovered species of rodent most closely related to the spiny rat. It was discovered in Peru, and is about the same size as a large squirrel, such as a Eurasian red squirrel. It inhabits the Peruvian cloud forest, where it forages for fruit and nuts...