Echimyidae Author Don E. Wilson Author Thomas E. Lacher, Jr Author Russell A. Mittermeier text 2016 2016-07-31 Lynx Edicions Barcelona Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I 552 604 book chapter 67690 10.5281/zenodo.6623649 5be7e52f-9b9c-4c03-99ed-f346bbcde1d0 978-84-941892-3-4 6623649 55. Orinoco Brush-tailed Rat Isothrix orinoci French: Rat-épineux de I'Orénoque / German: Orinoco-Borstenschwanzratte / Spanish: Rata de cola de cepillo del Orinoco Taxonomy. Loncheres bistriatus orinoci Thomas, 1899 , “Maipure, upper Orinoco,” Vichada, Colombia. Isothrix orinoct was long regarded as a subspecies of I. bistriata , but L. H. Emmons in 2005 elevated it to species status. Monotypic. Distribution. Amazon Basin of the upper Orinoco and Casiquiare rivers of extreme E Colombia and S Venezuela; it might occur in adjacent N Brazil. Descriptive notes. Head-body 207-257 mm, tail 168-278 mm. No specific data are available for body weight. The Orinoco Brush-tailed Rat is smaller than but similar to the Yellow-crowned Brush-tailed Rat ( I. bistriata ) and the Rio Negro Brush-tailed Rat (1. negrensis ). The Orinoco Brush-tailed Rat is distinct in having bright yellow stripe over head between eyes and ears, dulling to grizzled gray, passing on each side without sharp contrast into dark supraorbital lines, which themselves coalesce on neck immediately behind head to form broad , black band. Prominent bright yellow stripe does not contrast significantly with black lines. Ears are dulled gray, but prominent white post-auricular patches contrast sharply with blacking nuchal part of coalesced supraorbital lines. Tail is nearly equal to head-body length (82-108%) and is similar to that of the Rio Negro Brush-tailed Rat. Skull of the Orinoco Brush-tailed Rat conforms to other species of Isothrix , but rostrum is shorter and nasal bones are proportionally longer compared with the Rio Negro Brush-tailed Rat and the Yellow-crowned Brush-tailed Rat. Habitat. .owland evergreen forest, mostly in trees and rarely on the ground. Most collecting localities of Orinoco Brush-tailed Rats are near rivers and streams. Elevational range is primarily 100-260 m but also upward to top of Cerro Duido in Venezuela at 1600 m. Food and Feeding. There is no information available for this species. Breeding. There is no information available for this species. Activity patterns. There is no information available for this species. Movements, Home range and Social organization. There is no information available for this species. Status and Conservation. Classified as Least Concern on The IUCN Red List (under I. bistriata ). Additional studies on distribution, habitat, abundance, ecology, and conservation threats to the Orinoco Brush-tailed Rat are needed. Bibliography. Emmons (1990, 1997a, 2005), Patton & Emmons (1985), Patton et al. (2015), Pittier & Tate (1932), Thomas (1899d), Trouessart (1904), Tate (1935), Woods (1993), Woods & Kilpatrick (2005).