708.

Eastern New Guinea Mountain Rat

Rattus niobe

French: Rat niobé / German: Kleine Ostneuguinea-Ratte / Spanish: Rata de montana de Nueva Guinea oriental

Other common names: Moss-forest Rat

Taxonomy. Mus niobe Thomas, 1906,

Owgarra, 2750 m, Angabunga River, Papua

New Guinea

The R. niobe species complex ( R. niobe,

R. arrogans, R. pococki, and R. arfakiensis)

is in critical need of taxonomic revision. Rattus miobe previously included R. arrogans, R. pococki, and R. arfakiensis, but they are considered separate species here until there is a proper revision of the group. Rattus niobe as currently defined almost certainly represents multiple species because recent genetic studies found that it isnot monophyletic and non-monophyletically clusters variously with R. verecundus, R. steini, R. mordax, and R. praetor .

Distribution. E Central Cordillera and Huon Peninsula, New Guinea.

Descriptive notes. Head-body 100-135 mm, tail 115-140 mm, ear 15-4-19-6 mm, hindfoot 24-9-29-1 mm; weight 36-55-5 g. The Eastern New Guinea Mountain Rat is the smallest in the R. niobe species complex. Pelage is soft and without spines. Dorsal pelage is dark gray-brown, being nearly black and with rusty tipped hairs, and blends into ventral pelage. Venter is dark gray-brown, with cream to rufous-tipped hairs. Juveniles are duller in color. Feet are lightly covered in silvery and brown hair dorsally. Ears are dark brown and relatively long; vibrissae are long. Tail is ¢.100% of head-body length and unicolored dark brown, with short tail hairs. The mite genus Guntheria and a phoretic pseudoscorpion, Megachernes, have been recorded from the Eastern New Guinea Mountain Rat. Skull has small bulla, with narrow molars. There are three pairs of mammae: one pectoral and two inguinal. Diploid number is 2n = 32, FN = 60.

Habitat. Tropical moss forest, areas of degraded forest, and old rural gardens at elevations of 762-4050 m.

Food and Feeding. The Eastern New Guinea Mountain Rat is most likely herbivorous and noted to steal sweet potatoes on one occasion.

Breeding. Eastern New Guinea Mountain Rats reproduce year-round, but abundance of pregnant females is low year-round. Litters have only 1-3 young.

Activity patterns. Eastern New Guinea Mountain Rats are mostly nocturnal, although individuals have been caught during the day in dense grass and moss-covered areas. They are terrestrial, creating U-shaped burrows with two entrance holes, and have also been found in grass nests. In wet season on Mount Sisa, they select areas with dense cover (captured more commonly at ridge tops) but not in dry season (captured more often at bottoms of sinkholes and similar areas).

Movements, Home range and Social organization. Home ranges of Eastern New Guinea Mountain Rats are probably c.0-15 ha. They regularly move more than 60 m, and some males travel up to 300 m and 50 m in elevation.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Eastern New Guinea Mountain Rat has a wide distribution and large overall population. It is fairly easy to find, and there are no known major threats.

Bibliography. Bulmer & Menzies (1972), Durden (1991), Dwyer (1978), Flannery (1995b), Helgen (2007a), Leary, Singadan, Menzies, Helgen et al. (2016a), Musser & Carleton (2005), Robins et al. (2014), Rowe et al. (2011), Taylor, Calaby & Smith (1990), Taylor, Calaby & Van Deusen (1982).