Chaetomys subspinosus (Olfers, 1818)

Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Erethizontidae, Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona: Lynx Edicions, pp. 372-397 : 374

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Broomstraw-spined Porcupine

Chaetomys subspinosus

French: Coendou subépineux / German: Borstenbaumstachler / Spanish: Puercoespin espinoso

Other common names: Bristle-spined Porcupine, Bristle-spined Rat, Thin-spined Porcupine

Taxonomy. Hystrix subspinosa Olfers, 1818 ,

“Brazil.” Restricted by R. S. Voss and R. Angermann in 1997 to Salvador, Bahia, Brazil.

Placed in the family Echimyidae by B. D. Patterson and A. E. Wood due to alleged retention of deciduous premolars; however, these teeth are not actually retained. Recent molecular evidence, presence of a posterior carotid foramen (shared with all erethizontids), and a prehensile manus and pes structure similar to Coendou support inclusion in the Erethizontidae . Monotypic.

Distribution. SE Brazil, from Sergipe to N Rio de Janeiro states.

Descriptive notes. Head-body 360-450 mm, tail 260-275 mm; weight 1-2 kg. The Broomstraw-spined Porcupine is medium-sized and pale to dark brown, with long back and short legs. Head is round, with small ear pinnae that are usually difficult to see because they are buried in spines on the head; brown tufts of soft fur emerging above spines reveal pinnae. This is the only soft fur on the body. Medium-length mystacial vibrissae reach to ears. Muzzle is brown and almost naked. Somewhat bulbous nose is not greatly swollen. Skull is heavily built, with cranial sutures that remain evident in adults. Well-developed postorbital process of frontal bone almost touches well-developed postorbital process ofjugal bone. Head and shoulders are evenly and densely covered with short (c.15 mm), kinky spines that stand up and are sharp at tips. Spines extend onto dorsal pelage to rump and on legs and base oftail, and in contrast to spines on head, these are non-defensive, longer (c.50 mm) spines lacking hard, sharp points; they are stiff, slightly wavy dry bristles like straws on a broom. Spines are tricolored with pale yellow bases, dark brown middles, and pale brown tips. Tail lengths are ¢.60-70% of head-body lengths. Tail, thick at the base, is colored like back on proximal one-fifth of dorsal side and rusty colored on ventral side near base, becoming dark brown near tip. Tail tapers, becoming slender distally, and curls dorsally for prehension (although it lacks well-developed prehensile surface seen in some New World porcupines). Other than the base, tail is thinly haired, becoming almost naked nearits tip.

Habitat. Patches of native primary and secondary rainforest, gallery forest, and “restinga forest” (low-canopy coastal forest including palms and mangroves) with high vertical complexity. Although Broomstraw-spined Porcupines are found in degraded thickets lacking trees and “cabruca” plantations (cacao orchards with intact native tree canopies), these habitats are not preferred. They may co-occur with but are less common than the smaller Bahia Porcupine ( Coendou insidiosus). Preponderance of soft bristles covering the body rather than more sharp quills may limit the Broomstrawspined Porcupine’s ability to exploit some habitat resources used by the Bahian Porcupine and the Brazilian Porcupine ( C. prehensilis ) due to an increased risk of predation; as a result, the Broomstraw-spined Porcupine appears to have more arboreal and restricted habitat requirements than other Neotropical erethizontids.

Food and Feeding. The Broomstraw-spined Porcupine is a somewhat specialized folivore that prefers protein-rich and fibrous leaves from trees in the family Fabaceae —a diet that is also high in plant secondary metabolites. It is likely a hindgut fermenter based on its simple stomach anatomy and its long, large intestine and sacculated cecum. Feeding observations of Broomstraw-spined Porcupines revealed that they eat leaves from locally abundant and widespread pioneer tree species typical of early successional forests, indicating an ability to find food in disturbed forests.

Breeding. There is no information available for this species.

Activity patterns. Broomstraw-spined Porcupines are nocturnal and arboreal. They are active between 17:30 h and 05:40 h and show bimodal peaks of activity between 19:00 h and 20:00 h and again from c.03:00-04:00 h. During the day, they rest in sites covered by leaves and in tangles oflianas. Individuals observed in the wild spent 74% of their time resting, 14% feeding, 11% traveling, and 2% in other activities. Females met with their offspring for 20-170 minutes each night (21:00-02:00 h) but were otherwise solitary.

Movements, Home range and Social organization. Broomstraw-spined Porcupines are excellent climbers; they use their prehensiletail to assist in arboreal movement. They move slowly; their reduced activity levels may be an energy saving strategy to help compensate for a diet high in plant secondary metabolites and fiber. Broomstraw-spined Porcupines move through tree canopies c.10 m off the ground and on small diameter (lesser than 2 cm) substrates, with their tails usually coiled around branches or twigs. They descend to the ground to defecate, and deposit feces and urine in concealed latrines such as bromeliads and tree hollows. Average distance traveled per day for radio-tracked individuals was 277-5 m at a rate of 21-6 m/h in one study and 147 m/night in a second study. Activity, distance traveled, and home range size do not appear to vary with season, although Broomstraw-spined Porcupines spend more time resting and less time feeding on rainy nights. Broomstraw-spined Porcupines have relatively small home ranges of 0-5-9-5 ha, using minimum convex polygon methods; this may be the smallest home range size among Neotropical porcupines. Mean home range of adult males (6-6 ha) is at least three times larger than mean home range of adult females (2 ha). Most (94-99%) of a male’s home range overlaps with the home ranges of neighboring females. In contrast, a female’s home range typically overlaps only 13-45% with that of the neighboring male. Female home ranges overlapped very little with neighboring females, only up to 0-2%. Radio-tracked Broomstraw-spined Porcupines preferred secondary forest and were seldom found in highly modified vegetation types such as rubber plantations. They prefer large trees with moderate-to-high numbers of lianas and growing close to the forest edge and will frequently reuse individual trees in their home ranges. Some individuals prefer intermediate forest strata for diurnal rest sites. Social structure of Broomstraw-spined Porcupines is little studied, but during infrequent occasions in which individuals were seen together, it was usually a mother with her single offspring.

Status and Conservation. Classified as Vulnerable on The IUCN Red List. The Broomstraw-spined Porcupine is also listed as vulnerable on the Brazilian red list due to declining population sizes. Its distribution formerly extended from Sergipe to northern Rio de Janeiro, but many local populations are now extinct due to deforestation. Less than 17% of native forest remains within the current distribution of the Broomstrawspined Porcupine. Hunting pressure may also be contributing to their decline.

Bibliography. Bezerra et al. (2015), Castilho et al. (2013), Costa et al. (2005), Emmons (1997a), Falcdo et al. (2012), Faria et al. (2006), Fernandez, Barbanti et al. (2012), Fernandez, de Barros et al. (2015), Oliveira, P. A. et al. (2012), Patterson & Wood (1982), Ribeiro et al. (2009), Voss (2015), Voss & Angermann (1997), Wilson & Reeder (2005), Zortéa & de Brito (2010).

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Distribution. SE Brazil, from Sergipe to N Rio de Janeiro states.