169.

Northern Luzon Giant Cloud Rat

Phloeomys pallidus

French: Rat-tacheté de Nehring / German: Nordliche Riesenborkenratte / Spanish: Rata gigante de Luzon septentrional

Other common names: Northern Luzon Phloeomys

Taxonomy. Phloemys pallidus Nehring, 1890,

Luzon Island, Philippines.

Sometimes considered conspecific with P. cumingi, but its validity as a separate species has been demonstrated by several morphological and cytogenetic studies. Although they are almost certainly distinct species, there is high morphological variability within this species and the exact limits of this variability in association to the variability of P. cumingi are uncertain. Further studies are needed to clarify the morphological boundaries between the two Phloeomys species. Monotypic.

Distribution. N & C Luzon I, Philippines.

Descriptive notes. Head-body 387-427 mm, tail 320-349 mm, ear 34-39 mm, hindfoot 80-90 mm; weight 2.2-2.7 kg. The Northern Luzon Giant Cloud Rat is the largest murid and has pale gray-silver fur with a variable amount of brown over the shoulders, neck and upper back, sometimes being nearly completely gray-silver as well as having a brown face mask. Vibrissae are long and ears are short, rounded, well furred, and dark brown. Tail is long (¢.80% of head—body length) and densely covered with brown hairs. Feet are pale and less furred, having broad feet with stout claws. Northern Luzon Giant Cloud Rats have highly distinctive molars with high crowns, possessing a series of plates surrounded by tough enamel. Females have two pairs of inguinal mammae. Chromosomal complement is 2n = 40, FN = 60.

Habitat. Primary and secondary lowland, montane, and mossy forest, and heavily disturbed scrub. Sometimes found in suburban areas with dense vegetation. It occurs from sea level up to ¢.2300 m.

Food and Feeding. Northern Luzon Giant Cloud Rats are herbivorous, eating all kinds of soft plant matter, including lender leaves, bamboo shoots, various other vegetation, and some agricultural crops, making them a pest in some cases.

Breeding. Females reach sexual maturity at eight months while males reach it at 12-18 months. Breeding occurs year-round, with eight months between births. Estrus cycles last 10-15 days and a captive single male attempted to mount a female 3-5 times during estrus. Each copulation lasts 10-45 seconds. Signs of pregnancy include reddish and tilted teats and an increase in girth size. Gestation period is estimated to be between 65 and 95 days. The Northern Luzon Giant Cloud Rat generally has only a single young, although it is known to have twins on occasion. A photograph of an animal from the Bronx Zoo shows a reported two-week-old juvenile that was fully furred with eyes fully open and was sitting upright, implying that the young of this species develop rather quickly. In captivity, species of Phloeomys are reported to breed in all months except for January, March, and May. Young are carried by attaching themselves firmly to the nipple. Captive individuals of either this species or the Southern Luzon Giant Cloud Rat (P. cumingt) have lived up to nearly 14 years of age.

Activity patterns. Northern Luzon Giant Cloud Rats are nocturnal and arboreal. They forage in trees and onthe ground, and nest in hollow trees and logs.

Movements, Home range and Social organization. Northern Luzon Giant Cloud Rats are presumably solitary or with dependent young. They reportedly make loud, guttural calls after intervals ranging from seconds to minutes; the significance of these calls is uncertain.

Status and Conservation. Classified as Least Concern on The IUCN Red List despite facing many threats, including hunting and deforestation. Northern Luzon Giant Cloud Rats have a relatively wide distribution and are considered fairly common, although they have been hunted extensively in some regions, occasionally leading to local extinction.

Bibliography. Corbet & Hill (1992), Heaney, Balete & Ong (2008), Heaney, Balete & Rickart (2016), Heaney, Balete, Rickart, Veluz & Sarmiento (2004), Musser & Heaney (1992), Oliver et al. (1993), Rickart & Musser (1993), Pasicolan (1993), Rabor (1955), Thomas (1898b).