327.

Poncelet’s Giant Rat

Solomys ponceleti

French: Solomys de Poncelet / German: Poncelet-Nacktschwanzratte / Spanish: Rata gigante de Poncelet

Other common names: Poncelet's Naked-tailed Rat, Poncelet’s Solomys

Taxonomy. Unicomys ponceleti Troughton, 1935,

about 16 km inland from Buin, southern Bougainville Island, Solomon Islands.

This large rat was initially described, on basis of a young adult female and two skulls, in a new genus Unicomys, which is now placed under Solomys . A phylogenetic study by L. M. Bryant and colleagues in 2011 found it to be sister to S. salebrosus . Another giant rat from Buka Island, S. spriggsarum, is known only from subfossil archaeological material, and derived from fragments of about the same size as S. ponceleti . Monotypic.

Distribution. Bougainville I, and Choiseul I, NW Solomon Is. Fossils are known from Buka I.

Descriptive notes. Head-body 330 mm, tail 340-365 mm, ear 23-26 mm, hindfoot 71-5-77 mm; one female weighed more than 1000 g and a juvenile male 425 g. Measurements are from the holotype and one female from Choiseul. This, the largest Solomys, is a very striking animal. It has long, coarse fur, forming a crest or mane of very long hairs over head and neck; hairs are 50-65 mm long, reaching 80 mm on rump and tail base; face is very thinly haired on cheeks and around eyes. Upperparts and underparts are dark brown, almost black; the pinkish-white skin with scattered brown freckles shows through the coarse, thin fur. Tail is longer than head-body length, uniformly blackish, is basally (c.75 mm) haired, like the body, distal part almost naked, with one hair of 1 mm between each tail scale, scales non-overlapping. Ears are comparatively short and broad. All feet are sparsely haired above and naked on underside; hindfeet proportionally larger than hands, adapted to arboreal life with first and fifth digits extendible almost to a right angle, and second and fourth widelyseparable. Skull strongly built, with powerful zygomatic arches. Females have four mammae.

Habitat. Swampy areas. Most specimens were captured in swampy lowland forests. Poncelet’s Giant Rat does not occur in modified habitats;it is found only in primary lowland rainforest, where less disturbance and an abundance of food. According to T. Leary in 1993, preferred habitat on Choiseul was Terminalia brassii (Combretaceae) forests in interior of the island. Elevational range is from sea level to 200 m.

Food and Feeding. Diet is presumably composed of vines, fruits, figs, nuts, and leaves.

Breeding. Litter size is presumably 1-2 young. On Choiseul, in February 1990, an Australian Museum team captured a female and a juvenile male taken by local hunters from a large stick nest (resembling that built by an eagle); the nest was on a branch of a huge foresttree.

Activity patterns. Poncelet’s Giant Rat is nocturnal and arboreal.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Critically Endangered on The IUCN Red List owing to a drastic population decline, estimated to be more than 80% over the last ten years, inferred from losses of its forest habitat (extensive deforestation on Bougainville and Choiseul), and increased hunting pressures. Poncelet’s Giant Rat is threatened by logging, most especially selective logging of trees used for nesting. This murid is hunted both on Choiseul and on Bougainville, and hunting pressure on the latter has increased in recent years. Local hunters, who call this giant rat “Nagara,” say that they infrequently spot these rats while hunting, and kill and eat them when trees have been felled. It is not known if the species is present in any protected areas.

Bibliography. Boseto & Pikacha (2016), Bryant et al. (2011), Flannery (1995a), Flannery & Wickler (1990), Lavery et al. (2016), Leary (1993), Leary, Seri, Flannery, Wright, Hamilton, Helgen, Singadan, Menzies, Allison & James (2008), Musser & Carleton (2005), Pikacha (2008), Pikacha & Sirikolo (2009), Troughton (1935b, 1936a).