Trinomys gratiosus
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 gratiosus

description: 23.
Gracile Atlantic Spiny-rat
Trinomys gratiosus
French: Rat-épineux gracieux / German: Zierliche Atlantikstachelratte / Spanish: Rata espinosa gracil
Taxonomy. Proechimys iheringi gratiosus Moojen, 1948,
“Floresta da Caixa Dagua, Santa Teresa, Espirito Santo, Brazil; altitude 750 meters.”
J. Moojen described three taxa in 1948 as subspecies of Proechimys iheringi gratiosus, bonafider, and panema. M. C. Lara and J. L. Patton in 2000; transferred all to Trinomys, elevated gratiosus to species status, and treated bonafidei as a subspecies of T. iheringi. L.. M. Pessoa and colleagues in 2015 included panema as a junior synonym of the nominate subspecies gratiosus. Two subspecies recognized.
Subspecies and Distribution.
T.g.gratiosusMoojen,1948—SEBrazil,coastalEspiritoSantoandNERiodeJaneirostates,andinlandtoSMinasGeraisStateandItatiaiaNationalParkinNWRiodeJaneiroState.
T. g. bonafidei Moojen, 1948 — SE Brazil, coastal ranges of Rio de Janeiro State.
Descriptive notes. Head-body 163-232 mm,tail 150-220 mm; weight 162-270 g. Upper parts of the Gracile Atlantic Spiny-rat are ocherous buff and contrast with white venter. Bicolored tail is brownish above and white below and averages 90% of headbody length;it lacks conspicuous pencil of elongated hairs at tip. Aristiformsare darker along mid-dorsal region,so that back contrasts with paler setiforms on sides of body.
Aristiforms are long, up to 27 mm, relatively narrow, and relatively soft; they are gray at bases and blacken toward tips. Setiforms on mid-dorsal region are gray basally, also blacken toward tips, but possess sub-distal ocherous band. Hairs on forefeet and hindfeet are white on dorsal surfaces. Skull of the Gracile Atlantic Spiny-rat is slender, lacks conspicuousridges, and averages 50-6 mm. Incisive foramina are large (3-3-5-9 mm long), premaxillary part of septum is broad and extends more than one-half length of foramina opening, maxillary part is very constricted, septum is often incomplete, and vomer does not contribute to ventral aspect of septum. Post-orbital processes of zygoma are rounded, involving only squamosal. Auditory bullae are small, smooth, elongated, and inflated. Baculum has pronounced dorso-ventral curvature of proximal one-third, has lateral indentation near distal end, and broadens near proximal end but tapers at tip; distal end possesses weak medial depression and without distal wings. Both subspecies have the same 2n = 56, FN = 108, with large submetacentric Xchromosomes and small metacentric Y-chromosomes.
Habitat. Atlantic Forest at elevations above 600 m; subspecies bonefidei occurs in Alto Parana Atlantic Forest, Campos Rupestres Montane Savanna, and Serra do Mar coastal forests ecoregions, within primary and secondary evergreen forest with elevated humidity and dense overstory with trees with crowns at least 20 m in height. 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. There is no specific information available for this species, but the Gracile Atlantic Spiny-rat probably feeds on a variety of plant materials, including fruit and seeds, and insects.
Breeding. Females of subspecies bonafidei were captured in April and September, with 1-2 embryos.
Activity patterns. There is no specific information available for this species, but the Gracile Atlantic Spiny-rat is presumed to be primarily nocturnal.
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. Population trends of the Gracile Atlantic Spiny-rat are unknown but assumed to be large. There are no majorthreats; it is protected in several state and national parks, and its montane habitat is among the better preserved of the many forest types in the broad Atlantic Forest.
Bibliography. Carvalho & Salles (2004), Lara & Patton (2000), Leite (2003), Moojen (1948), Pessoa, dos Reis & Pessba (1996), Pessoa, Tavares, de Oliveira & Patton (2015).
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