325.

Masked White-tailed Giant Rat

Uromys hadrourus

French: Uromys du Thorntorn / German: Queensland-Riesenratte / Spanish: Rata gigante de cola blanca enmascarada

Other common names: Masked White-tailed Rat, Masked White-tailed Uromys, Pygmy White-tailed Rat, Thornton Peak Melomys

Taxonomy. Melomys hadrourus Winter, 1984,

Thornton Peak summit area, 1200 m, north-eastern Queensland, Australia.

Uromys has been found to be sister to a clade including Melomys, Solomys, and Paramelomys, as well as an undescribed taxon that may represent a separate genus that is indistinguishable from Melomys cervinipes . U. hadrourus was originally described in genus Melomys, but was later recognized as a species of Uromys on basis of morphological data. Within Uromys, hadrourusis placed under subgenus Uromys along with U. anak, U. boeadii, U. emmae, U. caudimaculatus, and U. neobritannicus . Monotypic.

Distribution. NE Queensland, Australia.

Descriptive notes. Head-body 170-185 mm, tail 184-196 mm, ear 20-25 mm, hindfoot 37-38 mm; weight 170-220 g. The Masked White-tailed Giant Ratis a very small Uromys, the smallest in the genus. Pelage is short and coarse, with dark guard hairs. Dorsal pelage is fawn or mid-brown with reddish tinge; a distinctive black eye-ring (absent in juveniles); ventral pelage is pure white, clearly demarcated from dorsal pelage. Feet are white, and shorter than those of the White-tailed Giant Rat ( U. caudimaculatus). Ears are grayish black, naked and rounded;vibrissae long and black. Tail is long (c.108% of head-body length), naked, and gray throughout, except for white tip;it lacks the mottling of the White-tailed Giant Rat. Skull is small, with inflated braincase and reduced postorbital processes. Seven species of nematode and various species of cestode, including Ophidascaris robertsi, Odilia wromyos, and Capillaria, have been recorded from the Masked White-tailed Giant Rat. There are two pairs of mammae, both inguinal. Chromosomal complement is 2n = 48, FN = 56.

Habitat. Restricted to rainforests with dense undergrowth and abundance of fallen logs on lower slopes and gullies and around headwater streams, at elevations of 550-1240 m.

Food and Feeding. The Masked White-tailed Giant Rat is omnivorous, feeding on seeds, invertebrates, sap and bark, and aerial tree roots.Its feeding habits appear similar to those of the White-tailed Giant Rat: it may tear apart logs and branches to catch passalid beetles and other insects, as well as eating hard-shellednuts such as creamy silky oak ( Athertonia diversifolia, Proteaceae), yellow walnut ( Beilschmiedia bancroftii, Laureaceae), and hairy walnut ( Endiandra insignis, Laureaceae). Like the White-tailed Giant Rat, it may also seasonally prefer bark over other foods, and tends to take in sap while chewing on bark.

Breeding. Adult males in breeding condition have been caught in September and December, and two subadult males (weighing 140 g and 145 g, respectively) were caught in June. Weights of captured juveniles and subadults indicate that breeding is focused around the early wet season, from late spring to summer (November—April). The Masked White-tailed Giant Rat probably lives to about 4-5 years, with a generation length estimated to be 2-3 years.

Activity patterns. Masked White-tailed Giant Rats are nocturnal, resting in a nest by day while foraging and moving about at night; there has been one record on an animal in Chowchillas foraging in mid-afternoon. The species is completely terrestrial, foraging on ground and nesting in burrows. Burrow entrances are typically hidden under leaf litter, in holes at base of trees, or under creek banks.

Movements, Home range and Social organization. Masked White-tailed Giant Rats are relatively vocal and make raspy honking calls that are quieter than those of the Whitetailed Giant Rat. Females make the most vocalizations; males rarely vocalize, although they are much more aggressive than females and will attack at slightest provocations. All animals involved in a feeding study were subsequently recaptured in the same places as where they were originally captured.

Status and Conservation. Classified as Near Threatened on The IUCN Red List. It was listed as Vulnerable in 2008, but was downgraded to Near Threatened after some reevaluation of the known distribution and threats, but is predicted to become Endangered in the near future. The Masked White-tailed Giant Rat has a relatively restricted and fragmented distribution, although most of its range is within the Wet Tropics World Heritage Area. The major threats to it seem to be global warming and logging, which lead to, respectively, climate and habitat alteration and forest fragmentation. The speciesis relatively difficult to capture, although it may be easier during droughts in the Lamins Hill area.

Bibliography. Bryant et al. (2011), Dickman et al. (2000), Groves & Flannery (1994), Menkhorst & Knight (2010), Moore (2010), Musser & Carleton (2005), Smales & Spratt (2008), Steppan & Schenk (2017), Van Dyck & Strahan (2008), Winter (1984), Woinarski & Burbidge (2016b), Woinarski et al. (2014).