326.

Rock-dwelling Giant Rat

Xenuromys barbatus

French: Rat barbu / German: Neuguinea-\ WeilRschwanzratte / Spanish: Rata gigante de roca

Other common names: Mimic Tree Rat, Rock-dwelling Rat, White-tailed New Guinea Rat

Taxonomy. Mus barbatus Milne-Edwards, 1900,

“Nouvelle-Guinée méridionale[= southern Papua New Guinea].”

Although Xenuromys has generally been regarded as morphologically close to Uromys, studies on sperm morphology by W. G. Breed and K. P. Aplin in 1995 point to relationship to the Pogonomys division, as treated in G. G. Musser and M. D. Carleton in 2005. This allocation is provisional, until phylogenetic analyses clarify relationships. X. guba is here treated as a synonym. Monotypic.

Distribution. Known from scattered localities in New Guinea, including the Central Range from Taritatu River E to Mt Dayman and the Torricelli Mts; possibly present across entire island of New Guinea in preferred habitat. It was found in Pleistocene archaeological sites on the Ayamaru Plateau, C Bird’s Head (= Vogelkop), NW New Guinea.

Descriptive notes. Head-body 275-340 mm, tail 220-284 mm, ear 25-36 mm, hindfoot 58-66 mm; weight 900-1100 g. This giant rat is externally similar to the Whitetailed Giant Rat ( Uromys caudimaculatus), but distinguished by shorter tail, larger tail scales, smaller and narrower head, more grayish upperparts, and very long vibrissae. Upperparts are reddish brown or grizzled grayish (guba); underparts are buffy or white (guba), with a tint of light cinnamon on neck and throat. Hands and feet are scantily haired, appearing naked, white. Ears are small, but not concealed in the fur, naked and fuscous. Tail is fuscous on basal half, and white on distal half; tail scales are set in overlapping rings, quite different from mosaic-patterned scales of Uromys; three small hairs per scale. Skull is like that of Uromys, less massive, with small supraorbital ridges, and small bullae as in Uromys . Mammae count is unknown; all reported specimens were males.

Habitat. Rocky habitats, in hilly or montane areas of broadleaf evergreen forest, at elevations of 0—-1600 m. Many of the recent records appear to be associated with karst outcrops or other rocky areas.

Food and Feeding. The Rock-dwelling Giant Rat apparently feeds on soft fruits, seeds, and insects. One stomach was full of pulpy rainforest fruit.

Breeding. No information.

Activity patterns. Rock-dwelling Giant Rats are possibly diurnal and nocturnal.

Movements, Home range and Social organization. Three males were captured during the afternoon in their lairs in rocky outcrops in dense rainforest in the Yapsiei area, Sandaun Province, in north-west Papua New Guinea. They attempted to escape by running along ground, rather than by climbing in to tree.

Status and Conservation. Classified as Least Concern on The IUCN Red List. Although apparently uncommon, the Rock-dwelling Giant Ratis quite widespread and is unlikely to be declining. It is moderately common at Mount Dayman and in Mount Sisa area of Papua New Guinea. There are no major threats to this species, although it is hunted for food by local people in parts of its range.

Bibliography. Aplin (2016n), Aplin etal. (1999), Boitani et al. (2006), Breed & Aplin (1995), Flannery (1995b), Flannery et al. (1985), Leary & Seri (1997), Menzies & Dennis (1979), Musser & Carleton (2005), Tate & Archbold (1941), Tate (1951).