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White-faced spiny tree-rat

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White-faced spiny tree-rat
White-faced brown rat on a log
In northeastern Brazil
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Infraclass: Placentalia
Order: Rodentia
Family: Echimyidae
Genus: Echimys
Species:
E. chrysurus
Binomial name
Echimys chrysurus
Synonyms[3]

Myoxus chrysurus Zimmermann, 1780
Echimys cristatus Desmarest, 1817
Echimys paleaceus Lichtenstein, 1820

The white-faced spiny tree-rat (Echimys chrysurus) is a species of spiny rat from South America.[4] Found in Brazil, French Guiana, Guyana and Suriname, it is restricted to forest and rainforest habitats, living among the branches and feeding on fruit, plants, and insects. The rat's dark fur is darkest near the back of the head, which also has a distinctive white stripe. Adults weigh up to 760 grams (27 ounces) and are from 24 to 33 centimetres (9.4 to 13.0 inches) long, plus a tail that measures about 120% of the head-body length.

The white-faced spiny tree-rat is nocturnal and produces two young in a litter. Because it is widespread and occurs in several protected areas, it is considered a least-concern species by the International Union for Conservation of Nature. Few studies on the rat's ecology have been performed, and there are not many museum specimens.

Systematics and etymology

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Illustration of black rat with white underbelly and partially yellow head and tail
18th-century engraving of the white-faced spiny tree-rat by Dutch draftsman Barent de Bakker, published in the work Histoire Naturelle

The white-faced spiny tree rat was first described by German zoologist Eberhard August Wilhelm von Zimmermann in 1780. He drew upon the Swiss-Dutch natural philosopher Jean-Nicolas-Sébastien Allamand's 1778 addition to the Histoire Naturelle[5] titled "Le Lerot à queue dorée" when writing his description. Zimmermann gave the species the scientific name of Myoxus chrysurus and wrote that its type locality was in Suriname.[6] The taxonomy of the white-faced spiny tree rat changed often throughout the 18th and 19th centuries; Allamand initially placed the species in the genus Hystrix, the Old World porcupines, and later authors would assign it to Glis, Loncheres, and Nelomys[6] before the currently accepted name, Echimys chrysurus, was assigned by Swiss naturalist Heinrich Rudolf Schinz in his 1825 translation of Le Règne Animal.[7] According to genetic analysis, the species is closely related to the dark spiny tree-rat (Echimys saturnus).[8]

The etymology of the species name derives from the two ancient Greek words χρυσός (khrusós), gold, and οὐρά (ourá), animal tail.[9][10] The genus name Echimys, and also its synonym Echinomys,[11] derive from the two ancient Greek words ἐχῖνος (ekhînos), meaning "hedgehog", and μῦς (mûs), meaning "mouse, rat".[9][10]

Habitat and distribution

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The white-faced spiny tree-rat is found throughout Guyana, Suriname, and French Guiana. It is known from the eastern Amazon Basin, but occurs south of the Amazon and east of the Xingu River in parts of Brazil.[1]

Vine-covered areas of lowland rainforests are the preferred habitat of the white-faced spiny tree-rat. It is a strictly arboreal species; it resides in the middle and upper strata of the rainforest and is found at elevations ranging from sea level up to about 200 metres (660 feet).[6] It is also known to live in open, primary forests.[1]

Description

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A brown rat with a white stripe on its head on a log photographed from the front
A white-faced spiny tree rat seen from the front, making the white median stripe on its head especially visible

White-faced spiny tree-rats typically weigh up to 760 grams (27 ounces) and have a length of 24 to 33 centimetres (9.4 to 13.0 inches) from the head to the base of the tail. The tail ranges in length from 25 to 40 cm (9.8 to 15.7 in), typically measuring 120% of the rodent's total head and body length. It is covered in hair and turns from brown to white towards the tip.[6] The rat's fur is made up of a mixture of broad, heavy spines and dark hairs that are brown at the tip and grey along the shaft. The fur near the back of the head is often darker than that along the rest of the animal's body.[12] Among members of the Echimyidae family, the genus Echimys has some of the most spinose guard hairs or spines, meaning that they are very stiff and robust and have blunt tips. The purpose of these hairs and differences within the family in terms of guard hair softness is thought to be tied to ancestral habitat preference and need for thermoregulation, as softer, denser fur is better at holding on to warmth.[13] The small ears of the white-faced spiny tree rat are slightly haired and brown. Its eyes are dark brown and have a red eye shine. The broad feet are covered with brown fur on top, and each digit has a claw.[6]

The main diagnostic character state or trait of this species is the presence of a white stripe on the head. As compared to Echimys vieirai and E. saturnus, the fur on the back of the white-faced spiny tree-rat is brighter.[14] The species is distinguished from other members of Echimys by several characteristics of its skull: its auditory bullae, bony structures that contain the inner ear, are of medium to small size, the external auditory meatus or ear canal is short, and it has a small internal auditory meatus, a bony canal connecting the inner ear to a cavity at the back of the skull (the posterior cranial fossa). The convex surface of the lower back of the skull, the squamous part of the occiptial bone, has short bony extensions on the lateral sides of the foramen magnum, an opening at the skull's back and lower part (the occiput). Nearby, the depression in the base of the skull known as the jugular fossa is broad and deep. Small, nearly circular openings or fenestrae are present ahead of (anterior to) the ear canals. The septum of the premaxillary bone, at the very tip of the upper jaw, is incompletely separated towards the back. The white-faced spiny tree-rat has parallel, rectangular rows of teeth, and its cheek teeth are longer than they are wide. The species' lower molars are very similar to those found in other tree-dwelling spiny rats (members of the family Echimyidae).[6]

Behaviour and ecology

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White-faced spiny tree-rats are nocturnal animals. They produce two young in a litter.[1] When startled by human or predator activity, they will move quickly across branches, but typically have a slow pace of movement. The species feeds on fruit, foliage, and some insects, mainly arthropods.[6] One known predator of the species is the ornate hawk-eagle.[15]

Conservation

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The white-faced spiny tree-rat has a stable population trend. It is potentially threatened by deforestation, though the 2016 report produced by Catzeflis and Patton for the International Union for Conservation of Nature (IUCN) did not consider this to be a major issue. They classified the species as least concern due to its wide distribution and presence in several protected areas.[1] It was previously classified as vulnerable in the 1996 issue of the IUCN Red List due to a perceived population decline caused by loss of habitat and threats by introduced species in Brazil.[16] Few museum specimens and ecological studies of the species exist.[6]

References

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  1. 1 2 3 4 5 Catzeflis, F.; Patton, J. (2016). "Echimys chrysurus". IUCN Red List of Threatened Species. 2016 e.T6979A22207079. doi:10.2305/IUCN.UK.2016-2.RLTS.T6979A22207079.en. Retrieved 20 April 2026.
  2. ↑ "Echimys chrysurus (Zimmermann, 1780)". Global Biodiversity Information Facility. Retrieved 10 March 2025.
  3. ↑ "Echimys chrysurus (Zimmermann, 1780)". ASM Mammal Diversity Database. American Society of Mammalogists. Retrieved 31 December 2025.
  4. ↑ Woods, C.A.; Kilpatrick, C.W. (2005). "Species Echimys chrysurus". In Wilson, D.E.; Reeder, D.M (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. p. 1578. ISBN 978-0-8018-8221-0. OCLC 62265494.
  5. ↑ Rookmaaker, L. C. (1992). "J.N.S. Allamand's additions (1769—1781) to the Nouvelle Edition of Buffon's Histoire Naturelle published in Holland". Bijdragen tot de Dierkunde. 61 (3): 131–162. doi:10.1163/26660644-06103001.
  6. 1 2 3 4 5 6 7 8 Fabre, Pierre-Henri; Patton, Jim; Leite, Yuri (2016). "Family Echimyidae (Hutias, Coypu and South American Spiny-rats)". In Wilson, D.E.; Lacher, T.E.; Mittermeier, R.A. (eds.). Handbook of the Mammals of the World. Vol. 6. Lagomorphs and Rodents I. Lynx Edicions. p. 633. ISBN 978-84-941892-3-4.
  7. ↑ Cuvier, Georges; Schinz, Heinrich Rudolf (1825). Das Thierreich eingetheilt nach dem Bau der Thiere als Grundlage ihrer Naturgeschichte und der vergleichenden Anatomie (in German). Vol. 4. Zoophyten. p. 387. doi:10.5962/bhl.title.115394 – via Biodiversity Heritage Library.
  8. ↑ Emmons, Louise H.; Fabre, Pierre-henri (9 March 2018). "A review of the Pattonomys/Toromys clade (Rodentia: Echimyidae), with descriptions of a new Toromys species and a new genus". American Museum Novitates (3894): 1–52. doi:10.1206/3894.1. ISSN 0003-0082.
  9. 1 2 Bailly, Anatole (1 January 1981). Abrégé du dictionnaire grec français. Hachette. pp. 874, 1308, 1424, 2160. ISBN 2-01-003528-3. OCLC 461974285.
  10. 1 2 Bailly, Anatole. "Greek-french dictionary online". Tabularium. Archived from the original on 18 March 2022. Retrieved 5 November 2017.
  11. ↑ Wagner, Johann Andreas (1840). "Beschreibung einiger neuer Nager, welche auf der Reise des Herrn Hofraths v. Schubert gesammelt wurden: mit Bezugnahme auf einige andere verwandte Formen". Abhandlungen der Mathematisch-Physikalischen Classe der Königlich Bayerischen Akademie der Wissenschaften (in German). pp. 191–210.
  12. ↑ Garst, Warren (October 1965), "White-faced tree rat standing on log", Garst (Warren and Genevieve) Collection, hdl:10217/54390 – via Digital Public Library of America
  13. ↑ Fabre, P.-H.; Patton, J. L.; Leite, Y. L. R. (2016). "Family Echimyidae". In Wilson, D.E.; Lacher, T.E.; Mittermeier, R.A. (eds.). Handbook of the Mammals of the World. Vol. 6. Lagomorphs and Rodents I. Lynx Edicions. pp. 563–565. ISBN 978-84-941892-3-4.
  14. ↑ Iack-Ximenes, Gilson Evaristo; de Vivo, Mario; Percequillo, Alexandre Reis (2005). "A new species of Echimys Cuvier, 1809 (Rodentia, Echimyidae) from Brazil". Papéis Avulsos de Zoologia. 45 (5): 51–60. doi:10.1590/S0031-10492005000500001. ISSN 0031-1049.
  15. ↑ Silva, Diego Afonso; Calaça, Analice Maria; Alencar, Raony Macedo; Faria, Michel Barros; Melo, Fabiano Rodrigues de (17 December 2024). "Predation of a rare white-faced tree rat Echimys chrysurus by the ornate hawk-eagle Spizaetus ornatus in a lowland Amazonian rainforest". Brazilian Journal of Mammalogy (93): e932024153–e932024153. doi:10.32673/bjm.vi93.153. ISSN 2764-0590.
  16. ↑ Baillie, Jonathan; Groombridge, Brian, eds. (1996). 1996 IUCN Red List of Threatened Animals (PDF). International Union for Conservation of Nature and Natural Resources. p. 28. ISBN 2-8317-0335-2.
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