707.

Eastern New Guinea Rat

Rattus mordax

French: Rat kaisi / German: Ostneuguinea-Ratte / Spanish: Rata de Nueva Guinea oriental

Other common names: Eastern Rat

Taxonomy. Mus mordax Thomas, 1904,

“8° 30” S. lat., 148° E. long.,” Kumusi River, Papua New Guinea.

Rattus mordax is in a clade of Recent New Guinea native species and seems to be close to R. steini, R. praetor, and R. novaeguineae . As currently defined, R. mordax probably represents multiple species, although more research is needed to determine this. Two subspecies recognized.

Subspecies and Distribution.

R.j.mordaxThomas,1904—ENewGuinea,includingtheHuonpeninsulaandPapuanPeninsula,WoodlarkI,andLouisiadeArchipelago .

R. j. fergussoniensis Laurie, 1952 — Goodenough, Fergusson, and Normanby Is, D’Entrecasteaux Is, off SE New Guinea.

Descriptive notes. Head-body 142-254 mm, tail 115-203 mm, ear 17-3— 21 mm, hindfoot 28-44 mm; weight 190-255 g. The Eastern New Guinea Rat is large, with coarse and long pelage and coarse spines throughout, being spinier in larger individuals. Dorsum is grizzled deep rust brown, with yellowish brown-tipped hairs and spines. Juveniles are darker and without spines. Venter is dull cream, with gray underfur, and might or might not have flexible spines; reddish brown patch on chin and anterior pectoralregion might be attributed to food stain. Feet are covered with short brownish hair. Ears are medium brown and sparsely haired; vibrissae are fairly short. Tail is ¢.80% of head-body length, unicolored medium brown, and sparsely covered with short hair. Subspecies mordax is larger than fergussoniensis . Skull 1s massive, with conspicuous supraorbital-temporal ridging that develops lateral projection in posterior supraorbital region. There are four pairs of mammae: two axillary and two inguinal. Chromosomal complementis 2n = 32; FN = 60.

Habitat. Various habitats including primary mossy tropical forest, tropical scrubland, eucalyptus savanna, secondary forest, rural gardens, and some villages atelevations up to 2800 m.

Food and Feeding. Eastern New Guinea Rats eat stored rice and sweet potatoes in villages and are said to eat fruits in the wild.

Breeding. Reproduction occurs year-round. Litters have 2-4 young (mean 2-3).

Activity patterns. No information.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Eastern New Guinea Rats is common and adaptable and does not face any major threats. It has been considered a pest to stored grains (rice) and sweet potatoes, although it is considerably less common than in the Large New Guinea Spiny Rat ( R. praetor) and Stein’s New Guinea Rat ( R. steini).

Bibliography. Aplin, Brown et al. (2003), Flannery (1995a, 1995b), Flannery et al. (1988), Musser & Carleton (2005), Robins et al. (2014), Taylor, Calaby & Smith (1990), Taylor, Calaby & Van Deusen (1982).