Trinomys setosus
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 setosus

description: 18.
Elegant-spined Atlantic Spiny-rat
Trinomys setosus
French: Rat-épineux velu / German: Haarige Atlantikstachelratte / Spanish: Rata espinosa peluda
Other common names: Hairy Atlantic Spiny-rat, Hairy Spiny-rat
Taxonomy. Echimys setosus Desmarest, 1817,
“Amérique.” Restricted byJ. Moojen in 1948 to “(southern?) Bahia,” Brazil.
Nomenclatural history of Trinomys setosus is complex, with many names used in earlier literature, now listed in synonymies of myosurus, leptosoma, cinnamomeus, Sfuliginosus, and denigratus. Two subspecies recognized.
Subspecies and Distribution.
T. s. setosusDesmarest, 1817 — EBrazil, coastalBahiaandEspiritoSantostates, andEMinasGeraisState.
T. s. elegans Lund, 1839 — SE Brazil, interior SE Minas Gerais and N Rio de Janeiro states.
Descriptive notes. Head—body 180-226 mm,tail 168-230 mm; weight 113-235 g. Dorsum of the Elegant-spined Atlantic Spiny-rat varies from brownish olive to cinnamon, gradually changing to olive or pale cinnamon on sides and outer thighs, and contrasting with white venter. Tail is slightly longer than head-body length;it is bicolored, brownish above and white below, and terminates in conspicuous whitish or cinnamon hairy pencil at its tip. In northernmost part ofits distribution, individuals tend to have very spiny appearance, but those in more southerly localities have softer pelage. Aristiform hairs on mid-dorsum are long (17-22 mm), wide in sefosus (mean 1-1 mm) but narrowerin elegans (mean 0-7 mm). Setiform hairs on mid-dorsum are gray basally, gradually blackening to tips but interrupted by middle cinnamon zone. Skull is large (average length 51-3 mm) and lacks conspicuous ridges. Incisive foramina are lyreshaped, long, and narrow (length averages c.44% of diastema), usually lacking conspicuous constriction at posterior end; septum is complete, with elongated premaxillary part that touches maxillary part, which is reduced to a small process. Post-orbital processes of zygoma are well developed, markedly spiniform but slender, and formed only by jugal. Auditory bullae are large and inflated. Upper premolars have two counterfolds; upper molars have 1-3 counterfolds. Bacular morphology varies within and between subspecies. Baculum of setosus may have dorso-ventrally curved shaft on proximal one-third, with lateral indentation near middle, broadening near proximal end and around tip, with concave distal end without either median depression or apical wings; others have narrow shaft that lacks any curvature or lateral indentations, rounded proximal end, and thin and concave distal end. In elegans, shaftis straight with any curvature or lateral indentations and has straight proximal end withoutlateral expansions and distal end without median depression or wings. Karyotype is variable, with differences apportioned between the two subspecies: sefosus is characterized by 2n = 56, FN = 108 and elegans by 2n = 56, FN = 104. X-chromosome in both subspecies is large acrocentric, and Y-chromosome is also acrocentric but one of the smallest elements in the complement.
Habitat. Atlantic Forest in coastal evergreen forests to interior, semideciduous forests at southern margins of Cerrado ecoregion and nearly always near water bodies. The Elegant-spined Atlantic Spiny-rat is reportedly a good swimmer and is known to construct nests in grass along lake margins.
Food and Feeding. The Elegantspined Atlantic Spiny-rat is primarily frugivorous, but it also opportunistically feeds on both insects and seeds.
Breeding. In coastal forests of Bahia State, a single female Elegant-spined Atlantic Spiny-rat captured in January gave birth to two young, weighing 27-8 g at birth; youngof-the-year have been captured in January-May, suggesting that breeding continues at least throughout those months. Breeding in semideciduous, interior forests is yearround, with peaks in mid-dry and mid-rainy seasons.
Activity patterns. There is no specific information available for this species, but the Elegant-spined 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. The Elegant-spined Atlantic Spiny-rat has a wide distribution;it is locally abundant across a variety of habitats from savanna edge to forests. There are no known major conservation threats, and it occurs in multiple protected areas.
Bibliography. Brants (1827), Desmarest (1817), da Fonseca & Kierulff (1989), Lichtenstein (1820, 1830), Moojen (1948, 1952b), Pessoa, Tavares, de Oliveira & Patton (2015), Wagner (1843).
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 562, DOI: 10.5281/zenodo.6623649