Mesomys stimulax Thomas 1911
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
Mesomys
Mesomys stimulax

description: 64.
Para Spiny Tree-rat
Mesomys stimulax
French: Rat-épineux du Para / German: Para-Amazonas-Stachelratte / Spanish: Rata arboricola de Para
Other common names: Central Brazil Spiny Tree-rat, Surinam Spiny Tree-rat
Taxonomy. Mesomys stimulax Thomas, 1911,
“Cameta, Lower Tocantins,” Para, Brazil. Mesomys stimulax was considered a subspecies of a polytypic M. hispidus by earlier authors. It is now recognized as a distinct species. Future studies may associate Rio Tapajos populations with M. hispidus; if so, distribution of M. stimulax would be limited to the region between Rio Xin-gu and Rio Tocantins.
Monotypic.
Distribution. E Amazon Basin of Brazil, S of the Amazon River, from the Rio Tapajos to the Rio Tocantins in Para State.
Descriptive notes. Head-body 154-196 mm, tail 122-199 mm; weight up to 139 g. The Para Spiny Tree-rat is smaller than most Amazonian populations of Ferreira’s Spiny Tree-rat (Mesomys hispidus). It differs from the latter byits buffier and paler overall dorsal pelage and distinct venter with white patches on throat, axilla, chest, and inguinal region; otherwise, belly is fawn colored. Tail is 79-101% of head-body length,is brown along its entire length, and terminates in very short tuft. Ears are short, rounded, and black, surrounded by long hairs. Forefeet and hindfeet are dorsally whitish, without buffy suffusion. Skull of the Para Spiny Tree-rat is small, with smaller proportions compared with western Amazonian populations of Ferreira’s Spiny Tree-rat, from which it can be distinguished by its shorter muzzle, nasal sides mesially parallel and narrower anteriorly rather than broader, and smaller tympanic bullae. Holotype has distinct incisive foramina, with premaxillary part converging anteriorly to narrow, straight-sided point and posterior part narrowing to form shallow grooves on anterior palate. Mesopterygoid fossa is straight-sided rather than bowed outward. Chromosomal complement is identical to that of Ferreira’s Spiny Tree-rat: 2n = 60 and FN = 116.
Habitat. Amazonian rainforest, uniformly in trees of terra firma forests at 4-10 m above the ground from sea level to elevations of ¢.250 m.
Food and Feeding. There is no specific information available for this species, but the Para Spiny Tree-rat likely has omnivorous to herbivorous habits of its congeners.
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 [IUCNRed List. Widespread forest clear-cutting following spread of roads in eastern Amazonia and increased natural fires may be negatively impacting the Para Spiny Tree-rat. Additional studies on distribution, habitat, abundance, ecology, and conservation threats are needed.
Bibliography. Cabrera (1961), Emmons (1990, 1997a, 2005), Orlando et al. (2003), Patton et al. (2015), Upham et al. (2013), Voss et al. (2001), Woods (1993), Woods & Kilpatrick (2005).
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 page 585, DOI: 10.5281/zenodo.6623649