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Phalanger gymnotisground cuscus

By Colleen Macke

Geographic Range

Ground cuscuses (Phalanger gymnotis) are found on the islands of New Guinea, Yapen, Misool, Salawati and the Aru Islands. Although rare, they have also been sighted in southernmost regions of New Guinea. ("Ground Cuscus", 2004; Flannery, 2004; Wilson and Reeder, 2005)

Habitat

Phalanger gymnotis occupies a variety of habitats including rainforests, caves and gardens. It is found from sea level up to 2,700 m but is most common at the lower end of its altitudinal range. Primarily terrestrial, P. gymnotis seeks refuge in dens, which are constructed in caves, under trees, and along stream beds. It may also be found in cultivated gardens, despite close proximity to humans. ("Ground Cuscus", 2004; George, 1987; Leary, et al., 2010; Majnep and Bulmer, 2007; Ramono and Nash, 1992)

  • Range elevation
    0 to 2,700 m
    0.00 to ft

Physical Description

Phalanger gymnotis has a short, coarse, grey-brown or silver-grey coat that contains a dark mid-dorsal stripe. Fur continues down the rump, covering the top of the tail. The remainder of the tail is covered in small bumpy growths that increase friction for gripping. Phalanger gymotis has little to no fur on the ears. The lack of fur on the ears and the dark dorsal stripe distinguish P. gymnotis from other members of its parent genus, Phalanger. At higher altitudes, tail fur is more dense and may have a white tip. Similar to other members of Phalanger, P. gymnotis has five digits on each foot, including a single opposable digit on the hind feet. The opposable digit is the only digit lacking a claw. Ground cuscuses vary in mass from 1,500 g to 4,850 g and in length from 310 mm to 539 mm. Tail length makes up a significant portion of its body length and ranges from 290 mm to 335 mm. Individuals in the northernmost part of its range tend to be larger, while individuals at higher altitudes are smaller than those a lower altitude. (Feiler, 1978; Flannery, 1995; Flannery, 2004; George, 1987; McNab, 2008)

The skulls of Phalanger gymnotis feature a powerful zygomatic arch and prominent sagittal crest, a narrow rostrum, and short paroccipital processes. Phalanger gymnotis is further divided into two subspecies, P. gymnotis gymnotis and P. gymnotis leucippus, which are differentiated by the wider palate and broader nasals of P. gymnotis gymnotis. The basal metabolic rate of P. gymnotis is 518.2 cm^3 oxygen/hour. Sexual dimorphism has not been reported in this species. (Feiler, 1978)

  • Range mass
    1,500.0 to 4,850.0 g
    to oz
  • Range length
    310.0 to 539.0 mm
    12.20 to 21.22 in
  • Average basal metabolic rate
    518.2 cm3.O2/g/hr

Reproduction

Little is known about breeding in Phalanger gymnotis in the wild. In captive populations, males court females by chasing and biting prospective mates when they are in estrus. Chasing may occur during daylight hours, but is most common at night, as Phalanger gymnotis is nocturnal. Although the mating system is unknown, it is either polygynous or polygynandrous, as males have been noted mating with at least two different females. (Shoemaker and Croxton, 1982)

Phalanger gymnotis mates year round and gives birth to a single newborn. Although gestation lasts 13 days, delayed implantation may occur, lengthening the time between copulation and birth. Females are almost always found to have a single young in their pouch, so the breeding interval is assumed to correspond with the length of time to independence for young. Young remain in the mothers pouch for approximately three months, at which point they exit the pouch at night. They continue to sleep in the pouch until the age of 5-7 months, when they leave permanently. Time to weaning is unclear as the continued use of the pouch makes weaning observations difficult. ("Ground Cuscus", 2004; Shoemaker and Croxton, 1982)

  • Breeding season
    Phalanger gymnotis breed year round
  • Range number of offspring
    1 (low)
  • Average gestation period
    13 days
  • Range time to independence
    5 to 7 months

Young are altricial and remain in the mother's pouch, not leaving permanently until the age of 5-7 months. The mother provides milk, but time to weaning is unknown. Young exit the pouch first at night, at approximately 3 months old. The young do not exit during the day to sleep alone until the age of 4 to 5 months. (Flannery, 1995; Shoemaker and Croxton, 1982)

  • Parental Investment
  • altricial
  • female parental care
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

The lifespan of wild Phalanger gymnotis is unknown, but individuals at least 15 years of age have been recorded in captivity. (Flannery, 1995; Goodnight, et al., 2007)

  • Range lifespan
    Status: captivity
    15 (high) years

Behavior

Outside of mating season, Phalanger gymnotis is solitary and asocial, and individuals are often aggressive toward conspecifics. Fighting is common and includes hissing, honking, foot thumping and striking opponents with the forelimbs. Phalanger gymnotis constructs terrestrial dens and forages in the mid to lower canopy at night. It generally remains on low, stable branches while foraging. Using a flexible, gripping tail and opposable hind thumbs, P. gymotis is an accomplished climber and can easily traverse forest habitats. Phalanger gymnotis is almost entirely nocturnal, however, some individuals have been seen outside their dens during the early morning. ("Ground Cuscus", 2004; Flannery, 1995; Shoemaker and Croxton, 1982; Wilson and Reeder, 2005)

Home Range

There is no information available regarding the home range of Phalanger gymnotis.

Communication and Perception

Phalanger gymnotis uses urine and cloacal gland secretions as scent markers. The scent, produced by both males and females, is said to smell like coffee. It likely uses pheromones to demarcate territorial boundaries and to attract potential mates. Ground cuscuses communicate vocally before and during mating and while fighting. While fighting, P. gymnotis hisses, honks, and foot thumps to communicate aggression. (Flannery, 1995; Shoemaker and Croxton, 1982)

Food Habits

Phalanger gymnotis is primarily frugivorous, but also consumes eggs, seeds, and leaves. It forages on the fruit and leaves of plants from numerous genera, including Elaeocarpus, Ficus, Pipturus, Pandanus, Oenathe, Rungia, and Ficus odoardii. Fruit is collected from trees and from the ground. Female ground cuscuses have been observed filling their pouches with fruit and then returning to their home dens where it is stored. (Flannery, 1995; Ganslosser and Etter-Ganslosser, 1990; Hume, et al., 1997; Mack and Wright, 2005; Wilson and Reeder, 2005)

  • Animal Foods
  • eggs
  • Plant Foods
  • leaves
  • seeds, grains, and nuts
  • fruit

Predation

Other than humans, Phalanger gymnotis has no documented predators. Humans prey upon P. gymnotis using traps, dogs, and traditional hunting methods. The nocturnal, solitary, and arboreal habits of P. gymnotis likely reduces risk of predation. (Leary, et al., 2010; Whitehead, 2000)

Ecosystem Roles

Fruit dispersion may be increased by Phalanger gymnotis. As large frugivores, ground cuscuses are one of the only species large enough to disperse virtually all fruits in the New Guinean rainforest. By translocating fruit and ingesting seeds, P. gymnotis is likely an important seed disperser throughout its geographic range. Parasites specific to this species have not been documented. (Mack and Wright, 2005; Shoemaker and Croxton, 1982)

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans: Positive

Phalanger gymnotis is hunted for its meat year round and is an important protein source for rural populations throughout Papua New Guinea. In some communities, P. gymnotis is consumed only by senior elders of the community and is considered to have medicinal qualities. (Dwyer, 1982; Leary, et al., 2010; Whitehead, 2000)

Economic Importance for Humans: Negative

Ground cuscuses may dwell in and around cultivated gardens and eat crops such as sweet potatoes. (Majnep and Bulmer, 2007; Ramono and Nash, 1992)

  • Negative Impacts
  • crop pest

Conservation Status

Although hunting has significantly reduced local populations of Phalanger gymnotis, the species remains widely distributed and is abundant throughout its geographic range. It is classified as a species of "least concern" on the IUCN's Red List of Threatened Species. In Indonesia, P. gymnotis is protected by law and cannot be captured, kept or traded. Until recently, it was acceptable for only the most senior members of many regional tribes in New Guinea to consume Phalanger gymnotis, and as a result, was infrequently hunted. As food taboos in rural villages changed during the 1970s and 1980s, P. gymnotis became an acceptable food source for members of almost all social levels resulting in increased pressure from hunting. ("Ground Cuscus", 2004; Flannery, 2004; Majnep and Bulmer, 2007; Ramono and Nash, 1992; Whitehead, 2000)

Other Comments

Phalanger gymnotis was formerly a member of the genus Spilocuscus, but molecular data led to its reclassification. It includes two subspecies, P. gymnotis gymnotis and P. gymnotis leucippus. (Feiler, 1978; Osborne and Christidis, 2002)

Contributors

Colleen Macke (author), University of Michigan-Ann Arbor, Phil Myers (editor), University of Michigan-Ann Arbor, John Berini (editor), Animal Diversity Web Staff.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

delayed implantation

in mammals, a condition in which a fertilized egg reaches the uterus but delays its implantation in the uterine lining, sometimes for several months.

drug

a substance used for the diagnosis, cure, mitigation, treatment, or prevention of disease

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

food

A substance that provides both nutrients and energy to a living thing.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

frugivore

an animal that mainly eats fruit

herbivore

An animal that eats mainly plants or parts of plants.

island endemic

animals that live only on an island or set of islands.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

suburban

living in residential areas on the outskirts of large cities or towns.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

year-round breeding

breeding takes place throughout the year

References

2004. Ground Cuscus. Pp. 64-65 in M Hutchins, D Kleiman, V Geist, eds. Grzimek's Animal Life Encyclopedia, Vol. 13, 2 Edition. Farmington Hills, MI: Thomson Gale.

Dwyer, P. 1982. pp. 529-542. Journal of Animal Ecology, Vol. 51, No. 2: pp. 529-542.

Feiler, A. 1978. Bemerkungen über Phalanger der "orientalis-Gruppe". Pp. 385-395 in Zoologische Abhandlungen, Vol. 34 Iss. 25. Leipzig, Germany: Akademische Verlagsgesellschaft Geest & Portig K.-G..

Flannery, T. 1995. Mammals of the South-West Pacific and Moluccan Islands. Ithica, NY: Cornell University Presss.

Flannery, T. 2004. Possums of the world : a monograph of Phalangeroidea. Chatswood, NSW, Australia: Geo Productions.

Ganslosser, U., R. Etter-Ganslosser. 1990. Phalangers. Pp. 308-309 in S Parker, ed. Grizmek's Encyclopedia of Mammals, Vol. 1, 1990 Edition. Hastings-on-Hudson, NY: McGraw-Hill, Inc..

George, G. 1987. Characterisation of the Living Species of Cuscus. Pp. 513-515 in M Archer, ed. Possums and Opossums: Studies in Evolution, Vol. 2. Chipping Norton, NSW: Surrey Beatty & Sons.

Goodnight, A., G. Couto, E. Green, M. Barrie, G. Myers. 2007. Chemotherapy and Radiotherapy for Treatment of Cutaneous Lymphoma in a Ground Cuscus. Journal of Zoo and Wildlife Medicine, Vol. 39, Iss.3: 472-475.

Hamilton, A., M. Springer. 1999. DNA Sequence Evidence for Placement of the Ground Cuscus, Phalanger gymnotis , in the Tribe Phalangerini (Marsupialia: Phalangeridae). Journal of Mammalian Evolution, Vol. 6 Iss. 1: 1-17.

Hume, I., M. Runcie, J. Caton. 1997. Digestive physiology of the ground cuscus (Phalanger gymnotis), a New Guinean phalangerid marsupial. Australian Journal of Zoology, Vol. 45 Iss. 6: 561-571.

Leary, T., R. Singadan, J. Menzies, K. Helgen, D. Wright, A. Allison, L. Salas, C. Dickman. 2010. "Phalanger gymnotis" (On-line). The IUCN Red List of Threatened Species. Accessed February 26, 2011 at http://www.iucnredlist.org/apps/redlist/details/16856/0.

Mack, A., D. Wright. 2005. The Frugivore Community and the Fruiting Plant Flora in a New Guinea Rainforest: Identifying Keyston Frugivores. Pp. 185-194 in A Mack, ed. Tropical Fruits and Frugivores: The Search for Strong Interactors. Heidelberg, Germany: Springer Netherlands.

Majnep, I., R. Bulmer. 2007. Animals the Ancestors Hunted. Belair SA, Australia: Crawford House.

McNab, B. 2008. The Comparative Energetics of New Guinean Cuscuses (Metatheria: Phalangeridae). Journal of Mammalogy, Vol. 85 Iss. 5: 1145-1151.

Osborne, M., L. Christidis. 2002. Molecular relationships of the cuscuses, brushtail and scaly-tailed possums (Phalangerinae). AUSTRALIAN JOURNAL OF ZOOLOGY, vol:50 iss:2: 135-149.

Ramono, W., S. Nash. 1992. Conservation of Marsupials and Monotremes in Indonesia. Pp. 13-19 in M Kennedy, ed. Australian Marsupials and Monotremes. Gland, Switzerland: IUCN. Accessed April 06, 2011 at http://data.iucn.org/dbtw-wpd/edocs/1992-026.pdf.

Shoemaker, A., J. Croxton. 1982. Husbandry and Reproduction of the Ground Cuscus Phalanger-gymnotis in Captivity. International Zoo Yearbook, Vol. 22 Iss.1: 176-180.

Whitehead, H. 2000. Food Rules: Hunting, Sharing and Tabooing Game in Papua New Guinea. Ann Arbor, MI: The University of Michigan Press.

Wilson, D., D. Reeder. 2005. Phalanger gymnotis. Pp. 46 in D Wilson, D Reeder, eds. Mammal Species of the World, Vol. 1, 3 Edition. Baltimore, Maryland: The Johns Hopkins University Press.

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