Trinomys iheringi
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
Trinomys
Trinomys iheringi

description: 22.
Sao Paulo Spiny-rat
Trinomys iheringi
French: Rat-épineux d'lhering / German: |hering-Atlantikstachelratte / Spanish: Rata espinosa de Ihering
Other common names: |hering’s Atlantic Spiny-rat, lhering’s Spiny-rat
Taxonomy. Proechimys iheringi Thomas, 1911,
“Island of Sao Sebastiao, off Sao Paulo, Brazil.”
Trinomys iheringi was originally placed in the subgenus Proechimys by O. Thomas and again by J. R. Ellerman in 1940, transferred to the subgenus Trinomys in 1948 by J. Moojen, and finally treated as a full species in the elevated genus Trinomys by M. C. Lara and J. L. Patton in 2000. MonoWDi ic.
Distribution. SE Brazil, littoral and plateau areas of SW Rio de Janeiro and Sao Paulo states, including Ilha Grande off the S coast of Rio de Janeiro State.
Descriptive notes. Head-body 185-220 mm,tail 170-224 mm; weight 139-233 g. Upperparts of the Sao Paulo Spiny-rat are cinnamon-buff, gradually lightening on sides, but contrasting with white venter. Bicolored tail is brownish above and white below and averages 87% of head—body length;it lacks conspicuous pencil of elongated hairs at tip. Aristiforms are darker along mid-dorsal region, so that back contrasts with paler setiforms on sides of body. Aristiforms are narrow and soft, up to 23 mm; setiforms on mid-dorsum are whitish basally, gradually blackening toward tips but with sub-distal cinnamon-buff zone. Hairs on forefeet and hindfeet are white dorsally. Skull is elongated and slender, but it has conspicuous ridges, averaging 51 mm. Incisive foramina are oval, short (length 3-7 mm, c.48% of diastema), and constricted posteriorly. Septum is always columnar in shape and complete, with short maxillary part and vomer that is not visible ventrally. Post-orbital processes of zygoma are rounded and formed by jugal and squamosal. Auditory bullae are small, smooth, and not inflated. Upper molariform teeth of the Sao Paulo Spiny-rat have three primary folds, with rudimentary fourth fold on M?: lowerteeth also have three folds, first are smaller than the others. Baculum is shorter than those of most other species (6-7 mm), lacks any dorso-ventral curvature or lateral indentations; distal end is evenly rounded, lacking distal wings or median depression; and proximal end is rounded. Chromosomal complement is 2n = 60-65 due to presence of B-chromosomes; excluding these latter elements, FN = 116. X-chromosomeis large submetacentric, and Y-chromosome is minute metacentric. Presence of B-chromosomes and minute Y-chromosome differentiate the Sao Paulo Spiny-rat from Rio de Janeiro Spiny-rat (71. dimidiatus).
Habitat. Atlantic Forest biome, primarily in the Serra do Mar Coastal Forest ecoregion, at elevations above 600 m. The Sao Paulo Spiny-rat occurs in primary and secondary evergreen forests with elevated humidity and dense overstory and trees at least 20 m high. Ground terrain in these forests is typically moderately steep, with rocky outcrops and relatively few fallen logs on the ground. Understory usually reaches 1-5 m in height, includes many palms and fruit trees, but has few lianas and vines, with some arboreal bromeliads and abundant arborescent.
Food and Feeding. The Sao Paulo Spiny-rat has been reported to be a scatter hoarder of, at least in one study, seeds of the understory palm Astrocaryum aculeatissimum (Arecaceae). Otherwise, it probably eats a variety of fruits, seeds, and insects.
Breeding. Reported litters of the Sao Paulo Spiny-rat have only 1-2 embryos. On Ilha do Cardoso, Sao Paulo State, reproduction and survival of females were directly related to food availability, particularly fruit, and rainfall; individuals reproduced yearround and without any seasonal pattern, although with a slight peak at the end of the dry season and beginning of the next wet season. As a result, adults were most abundant during middle to end of the rainy season.
Activity patterns. There is no specific information available for this species, but the Sao Paulo Spiny-rat is presumed to be primarily nocturnal.
Movements, Home range and Social organization. Home ranges of Sao Paulo Spinyrats are large, especially compared with other rodent species of equivalent size that inhabit similar rainforests. Males use larger areas than females, and female ranges are exclusive—attributes suggesting polygynous mating system. Home ranges average 1-1 ha for males and 0-86 ha for females. Available forest cover, fruit productivity, resource competition, and overabundance of mesopredators might limit local population size.
Status and Conservation. Classified as Least Concern on The IUCN Red List. The Sao Paulo Spiny-rat has a wide distribution and presumably large population sizes. Population trends are unknown but assumed to be large. There are no major threats; it is protected in several state and national parks, and its montane habitat is better preserved among varied forest types in Atlantic Forest.
Bibliography. Bergallo (1994, 1995), Bergallo & Magnusson (1999), Bergallo et al. (2004), Bovendorp et al. (2013), Donatti et al. (2009), Ellerman (1940), Lara & Patton (2000), Moojen (1948), Pess6a & dos Reis (1996), Thomas (1911Db).
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 564, DOI: 10.5281/zenodo.6623649