704.

Manus Island Spiny Rat

Rattus detentus

French: Rat de Manus / German: Manus-Ratte / Spanish: Rata espinosa de Manus

Other common names: Admiralties Rat

Taxonomy. Rattus detentus Timm et al., 2016,

“asmall stream near western end ofKawaliap Village, el. 200 m (2°6’40”S, 147°3’40”E), Manus Island, Admiralty Islands, Manus Province, Papua New Guinea.”

Rattus detentus 1s basal to all other species in the Recent New Guinea clade in Rattus . Monotypic.

Distribution. Manus I, Papua New Guinea (natives claim Los Negros Is).

Descriptive notes. Head-body 260 mm, tail 150 mm, ear 23-4 mm, hindfoot 43-2 mm. No specific data are available for body weight. The Manus Island Spiny Rat is large and heavily built, with long, harsh, and spiny pelage. Dorsum is dark gray, heavily flecked with pale gray and many translucent spines, some with rufous or dark tips; prominent black guard hairs (longer on rump) are mixed throughout. Dorsal underfur is pale gray, and fur on outer parts of limbs is lighter. Rhinarium is white, and sides of rostrum have short dark hairs. Venter is white and lacks spines. Feet are white, with dark pigment speckling caused by short dark hairs thinly covering dorsal part. Claws are robust and ivory. Undersurface offeet has irregular gray patches. Ears are white at bases, grayer toward ends; vibrissae are fairly long and black. Tail is only ¢.58% of head-body length, dark gray throughout with paler mottling at very base, and covered with short bristly hair. Skull has elongated and anteriorly broadened rostrum, relatively short and bowed incisive foramina that terminate anterior to molar rows and short and uninflated auditory bullae. There are four pairs of mammae: one pectoral, one post-axillary, and two inguinal pairs.

Habitat. Mosaic of Metroxylon (sago) palms ( Arecaceae) and mixed tapioca ( Manihot esculenta, Euphorbiaceae), vegetable gardens, and secondary regrowth scrub from sea level to elevations of ¢.200 m.

Food and Feeding. The Manus Island Spiny Rat might feed on fallen nuts of Canarium indicum ( Burseraceae), as indicated by conspicuous gnawing on nuts, but this might also be caused Pacific Rats ( R. exulans).

Breeding. Holotype of the Manus Island Spiny Rat was carrying two fetuses, each 1 cm long.

Activity patterns. The Manus Island Spiny Rat might be nocturnal and terrestrial; it makes nests in burrows.

Movements, Home range and Social organization. No information.

Status and Conservation. Not assessed on The IUCN Red List. The Manus Island Spiny Rat seems to be rather rare and might compete with the Pacific Rat. Lowlands and coastal region of Manus Islands are largely deforested and replaced by plantations. The species is commonly hunted by natives for food. It is reported to be common by natives, although it seemsto be hardto capture, and populations might be decreasing. Additional research is needed to fully understand its natural history and conservation threats.

Bibliography. Timm, Weijola et al. (2016).