Echimys chrysurus Zimmermann 1780
Creators: name: Don E. Wilson
name: Thomas E. Lacher, Jr
name: Russell A. Mittermeier
Publisher: name: Lynx Edicions
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Rodentia
Echimyidae
Echimys
Echimys chrysurus

description: 82.
White-faced Tree-rat
Echimys chrysurus
French: Rat-épineux a face blanche / German: \WeiRnasen-Stachelratte / Spanish: Rata arboricola de cara blanca
Other common names: \ White-faced Spiny Tree-rat
Taxonomy. Myoxus chrysurus Zimmermann, 1780,
“Surinam [= Suriname],” based on Allamand’s (1778) “lérot a queue dorée.”
Generic assignment of E. chrysurus varied extensively in the 18" and 19™ centuries; it was initially assigned to Hystrix and subsequently to Myoxus, Glis, the South American Loncheres, Nelomys and appropriately to Echimys. Monotypic.
Distribution. The Guianas and Guianan region of NE Brazil and E Amazon Basin E of the Rio Negro and N of the Amazon River, but extending S of the Amazon to the E of the Rio Xingu in E Brazil.
Descriptive notes. Head-body 242-333 mm, tail 250-395 mm; weight up to 760 g. The White-faced Tree-rat is large, with dark gray-brown dorsum densely covered with large spines from neck to rump. Remainder of pelage is composed ofstiff and harsh bristles. Throat, chin, and inguinal areas are white, and white stripe occurs on chest; all other ventral parts are gray-brown, not very different from upper parts. Pale yellowish to whitish blaze extends down center of head from crown to nose; it may completely cover face, appear as narrow stripe, or otherwise be present only as small white tuft on crown. Eyes are dark brown, with weak typical red eye shine. Cheeks, sides of crown, and chin are usually dark brown or reddish. Ears are small, slightly haired, and brown. Tail is c.120% of head-body length, fully haired from base to tip, and longitudinally bicolored with dusky basal part and white distal end covering two-thirds of its length. Feet are broad, with powerful claws on all digits, and gray-brown above. Skull of the White-faced Treerat is similar among species of Echimys, but quite distinct compared with other genera by virtue of small to medium bullae, small auditory meatus, short auditory tube thatis oriented laterally, and external meatus short and positioned close to squamosal. Lateral process of supraoccipital is short; squamosotympanic fenestra is small and nearly circular and located anteriorly compared with auditory meatus; premaxillary septum of incisive foramina is incomplete posteriorly; and jugal fossa is broad and deep below post-orbital process. Mandibular foramen is anterior to condyloid ridge, outside fossa of anterior ascending branch ofjaw. Tooth rows are parallel and rectangular, and very high-crowned cheekteeth are longer than wide. Upper teeth have two U-shaped lophs of similar orientations that fuse with wear. Lower dP, is divided into three lophids: anteroconid-anterolophid, metalophid, and enterolophid-posterolophid. Lower molars are similar to other arboreal echimyids that have sigmoid lophid shapes.
Habitat. Mature lowland rainforest, primarily middle and upperstrata, especially vinecovered areas, but also open forest, from sea level to elevations of ¢.200 m.
Food and Feeding. Stomach contents and field observations of White-faced Tree-rats indicate a frugivorous—folivorous diet, but some insects are eaten. Analysis of the 6"°C isotope in White-faced Tree-rats in comparison to more terrestrial rodent species suggested a primary diet of C, plants, with potential consumption ofa significant proportion of arthropods.
Breeding. A female White-faced Tree-rat was found with two embryos.
Activity patterns. White-faced Tree-rats are strictly arboreal and nocturnal.
Movements, Home range and Social organization. White-faced Tree-rats usually move slowly along branches, but speed increases under duress from human disturbance or predators. Mean distance traveled was estimated at 294 m/night based on tracking data and nest locations.
Status and Conservation. Classified as Least Concern on The IUCN Red List. The Whitefaced Tree-rat has a wide distribution, and ease of capture and common sightings by zoologists and general extent ofits natural habitat make it presumably less prone to threats from human activity. Additional ecological studies, however, are encouraged in view ofrarity of specimens in museum collections, preference for mature primary forest, and general lack of focused fieldwork.
Bibliography. Allen (1899a), Cuvier (1809), Desmarest (1817), Eisenberg & Redford (1999), Eisenberg & Thor ington (1973), Emmons (1990, 1997a, 2005), Geoffroy Saint-Hilaire (1840), Gloger (1841-1842), lack-Ximenes et al. (2005), llliger (1811), Jourdan (1837), Link (1795), Mares (1982), Mauffrey (1999), Mauffrey & Catzeflis (2003), Mauffrey et al. (2007), Miles et al. (1981), Miranda-Ribeiro (1914), von Olfers (1818), Patton et al. (2015), Richard-Hansen et al. (1999), von Schreiber (1792), Thomas (1916b), Treviranus (1803), Wagner (1840), Woods (1993), Woods & Kilpatrick (2005), Zimmermann (1780).
description: Published as part of Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Echimyidae, pp. 552-604 in Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona :Lynx Edicions on pages 593-594, DOI: 10.5281/zenodo.6623649