Phalanger sericeus, Thomas, 1907

Russell A. Mittermeier & Don E. Wilson, 2015, Phalangeridae, Handbook of the Mammals of the World – Volume 5 Monotremes and Marsupials, Barcelona: Lynx Edicions, pp. 456-497 : 492-493

22.

Silky Cuscus

Phalanger sericeus

French: Phalanger soyeux / German: Seidenkuskus / Spanish: Cuscus sedoso

Taxonomy. Phalanger sericeus Thomas, 1907 ,

“ Owgarra , Angabunga River (near the Aroa River), S.E. New Guinea. Altitude 6000.”

Two subspecies are recognized.

Subspecies and Distribution.

P.s. sericeus Thomas, 1907 — E New Guinea Central Range (E of 143°E).

P s. occidentalis Menzies & Pernetta, 1986 — W New Guinea Central Range (W of 143°E).

An additional isolated population was recently documented on the outlying volcanic peak of Mt Bosavi in SC Papua New Guinea.

Descriptive notes. Head-body 37-5—46 cm,tail 27-32 cm; weight 1.7-2.4 kg. The Silky Cuscusis a medium-sized cuscus (condylobasal length 70-85 mm). It can be identified by a combination of very thick, dark, silky fur; a smooth tail; small, conical third premolar; absent upper second premolar; and only one or two lower unicuspids. These features help to distinguish the Silky Cuscus from the Mountain Cuscus ( P. carmelitae ), with which it is most easily confused, and Stein’s Cuscus ( P. vestitus ), with which it was taxonomically confused in the past. Externally, the Silky Cuscus and the Mountain Cuscus can be distinguished most easily by the tail, which is not tuberculated in the Silky Cuscus (strongly so in the Mountain Cuscus) and has a short white tip if present at all (usually longer, prominent, white tip in the Mountain Cuscus).

Habitat. Most primary montane forests along the Central Range at elevations of c.1500 m to the tree line at ¢.3900 m. The Silky Cuscus is uncommon in primary oak forest in the Telefomin region at elevations of ¢.1500 m, where it is sympatric with the Ground Cuscus, the Telefomin Cuscus, the Mountain Cuscus, and Stein’s Cuscus. In more disturbed forests, such as on Mount Albert Edward, the Silky Cuscus appears to be restricted to a higher elevation of ¢.2000 m, where it is sympatric with the Mountain Cuscus. In this region, the Silky Cuscus is most common at elevations of 2900-3100 m. Due to their adaptation to higher elevations where they naturally occur, Silky Cuscuses appear to readily suffer heat stress if moved to lower elevations.

Food and Feeding. The Silky Cuscus appears to be mostly folivorous, with more than 90% of its diet being leaves and the remainder fruits. Genera of plants eaten by Silky Cuscuses include Acronychia (Rutaceae) , Elaeocarpus (Elaeocarpaceae) , Eurya (Pentaphylacaceae) , Garcinia (Clusiaceae) , Litsea (Lauraceae) , Planchonella (Sapotaceae) , Podocarpus (Podocarpaceae) , Syzygium (Myrtaceae) , and Trema (Cannabaceae) . Leaves of regrowth plants and fruit of Casuarina (Casuarinaceae) and Cordyline (Asparagaceae) are also eaten; leaves of Pandanus (Pandanaceae) are masticated and fiber spat out.

Breeding. Limited observations of breeding characteristics of Silky Cuscuses include a single pouch young recorded in December, another female with a single enlarged nipple in December, and a female with a young on her back in December. Two females were observed in late April with single young on their backs, weighing 740 g and 910 g.

Activity patterns. The Silky Cuscus is nocturnal and rests during the day in hollows of large rainforest trees. There are reports of them nesting on the ground among stones and in tree stumps. Field observations showed that male Mountain Cuscuses used up to 22 dens/year that were spaced an average of 97 m apart; a radio-collared female used nine dens in 61 days. During the night, Silky Cuscuses spend ¢.50% oftheir time eating, ¢.25% resting, and the remainder traveling.

Movements, Home range and Social organization. Male Silky Cuscuses travel an average of 50 m/h. When captured, Silky Cuscuses can emit a loud barking snarl; another call resembles crying of a very young human baby.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Silky Cuscus has a wide distribution and presumably a large overall population. It is threatened especially by hunting for food.

Bibliography. Flannery (1994a, 1995a), Leary, Singadan, Menzies, Helgen, Wright, Allison, Hamilton, Aplin et al. (2008), Menzies & Pernetta (1986), Salas (2002).

Figures

11. Peleng Cuscus (Phalanger pelengensus), 12. Moluccan Cuscus (Phalanger ornatus), 13. Gebe Cuscus (Phalanger alexandrae), 14. Obi Cuscus (Phalanger rothschildi), 15. Ground Cuscus (Phalanger gymnotis), 16. Woodlark Cuscus (Phalanger lullulae), 17. Northern Common Cuscus (Phalanger orientalis), 18. Eastern Common Cuscus (Phalanger intercastellanus), 19. Southern Common Cuscus (Phalanger mimicus), 20. Telefomin Cuscus (Phalanger matanim), 21. Stein’s Cuscus (Phalanger vestitus), 22. Silky Cuscus (Phalanger sericeus), 23. Mountain Cuscus (Phalanger carmelitae), 24. Black Spotted Cuscus (Spilocuscus rufoniger), 25. Waigeo Spotted Cuscus (Spilocuscus papuensis), 26. Admiralty Spotted Cuscus (Spilocuscus kraemeri), 27. Blue-eyed Spotted Cuscus (Spilocuscus wilsoni), 28. Common Spotted Cuscus (Spilocuscus maculatus), 29. Australian Spotted Cuscus (Spilocuscus nudicaudatus)

Subspecies and Distribution. P.s. sericeus Thomas, 1907 — E New Guinea Central Range (E of 143°E). P s. occidentalis Menzies & Pernetta, 1986 — W New Guinea Central Range (W of 143°E). An additional isolated population was recently documented on the outlying volcanic peak of Mt Bosavi in SC Papua New Guinea.