Ringtail and greater gliding possums

(Pseudocheiridae)

Class Mammalia

Order Diprotodontia

Family Pseudocheiridae

Thumbnail description
Medium-sized possums, most species rather slow-moving, with short limbs; their teeth, particularly molars, have selenodent (i.e., half-moon shaped) crests, ideal for cutting and grinding leaves; ears are small and furred, fur color is mostly brown or gray with the last part of the (prehensile) tail more or less hairless

Size
12.6–37.4 in (320–950 mm), 4.1–79.4 (115–2250 g)

Number of genera, species
6 genera; 16 species

Habitat
Forests and woodlands, suburban areas

Conservation status
Vulnerable: 3 species; Lower Risk/Near Threatened: 4 species; Data Deficient: 3 species

Distribution
New Guinea, Australia including Tasmania

Evolution and systematics

Pseudocheiridae are most closely related to Petauridae, and together they form a superfamily Petauroidea. Even though this superfamily is named after petaurids, the pseudocheirids are obviously the more primitive and generalized family. This is evident both from morphology and from paleontological data. Pseudocheirids have been found in very old Tertiary deposits. The oldest undoubtedly pseudocheirid known so far comes from the late Oligocene-middle Miocene, and those genera are already rather distinct from each other. Oligocene as well as Quaternary species have been found in several central Australian and Queensland records, which points to a wide-ranging distribution already there. These paleontological data, together with the fact that today only two genera (nine species) live in New Guinea, but six genera (seven species) live in Australia, suggest that the family had its origin in Australia and immigrated into New Guinea quite recently. Dental morphology of pseudocheirids is also considered rather primitive: The W-shaped molars are considered (Archer) as more primitive than the rounded cusps of petaurids. Even though koalas also have similar molar crowns, this is being regarded as a convergence due to leaf-eating. Both cytogenetic studies and albumin microcomplement fixation techniques have yielded quite clear-cut results recently concerning taxonomy within the family. No subfamily has been erected, but Hemibelideus and Petauroides are closely related to each other, and only distantly related to the rest. Petropseudes and Pseudochirops similarly are separate from the rest, but also with a certain distance between the two genera. Pseudochirulus, which now contains several species previously assigned to Pseudocheirus, also is an isolated genus. Some of the species (e.g., P. peregrinus, Pseudochirulus canescens) are subdivided into up to six subspecies, which is further evidence for both long isolation and old radiations.

Physical characteristics

The greater glider Petauroides volans is quite distinct from the rest of the family. It possesses a gliding membrane from elbows to lower legs similar but convergent to Petaurus spp., and a bushy tail. Its ears are large, the fur is long and woolly, and varies from white or gray to dark brown, sometimes with tail and body being in different colors. Its size puts it apart, with up to 37.4 in (95 cm) head-to-tailtip, and a weight of 32.8–42.3 oz (930–1,200 g). The rest of the family, in external

appearance is rather similar. All have short, stocky limbs, short round ears, and tails that are bare at the lower side at least about the final third of their lengths. Many species have dorsal stripes, though these are not always clearly seen when the fur itself is rather dark. Fur colors differ from light gray/cream, to orange, to dark brown. One species is greenish due to a mix of yellow, black, and white hairs. Internally, all species (including Petauroides) have a large cecum for fermenting their leaf-based diet, and their cheek-teeth are formed in the shape of cutting edges, scissorlike, to both cut and grind xerophytic leaves (e.g., Eucalyptus, which at least some species can detoxify).

Distribution

Pseudocheirids obviously already were part of the Australian fauna in times when the Australian continent still rested in wetter climatic zones. Species existing then, similar to other families, were larger than today's representatives, reaching up to 33 lb (15 kg). With increasing aridification of the Australian continent, pseudocheirids withdrew to the still wetter areas, and today are restricted to coastal, or coast-near areas in the east, northeast, southwest and northwest of the continent, as well as Tasmania. New Guinea seems to have been invaded rather late, and the species there are mostly restricted to mountainous, i.e., central areas.

Habitat

Nearly all of the New Guinean species, except for two rather poorly known and obviously rare species (Pseudochirulus canescens, Pseudocheirus caroli), inhabit mountain forests, where they are rather abundant. All of them prefer primary forests except Pseudocheirus forbesi, who seem to be more adapted to secondary, i.e. disturbed forest areas. There are up to four sympatric species in certain New Guinean places, and in those communities there are clear niche-separations in size, ranging from 5.3 to 70.5 oz (150 to 2,000 g) and nesting habits (from tree-hollows to dreys to sleeping exposed on branches). In Australia, one species (Petropseudes dahli) is semi-terrestrial, preferring rocky areas in Northern Australia, two species are found in sclerophyll forests (P. volans and Pseudocheirus peregrinus),

and the rest are living in higher altitude rainforests of the Atherton Tableland. Contrary to New Guinea, these sympatric species (which also are in part sympatric to some phalangerid species) are all in the same size class, namely, in the 31.7–42.3 oz (900–1,200 g) range, and all except one, rest in tree-hollows. Supposedly, niche-differentiation must be along some other axes, one of them possibly activity—each species has characteristic times of emerging and returning from and to nests, the aspect of the nesting-tree, or size of the hollows. Among the sclereophyll forest-dwellers, Pseudocheirus peregrinus has been able to adapt to suburban habitats, feeding on rosebuds and rose leaves in front- and backyards, and daynesting under roofs.

Behavior

Pseudocheirids are among the most diverse of all possums in term of social organization. The rock ringtail (Petropseudes dahli) seems to live in long-term pairs with overlapping young, as they have been observed as pairs with a young-at-heel, and another smaller one riding on back. Lemuroid ringtails are long-term monogamous, perhaps with a potential to an expansion similar to P. dahli, P. peregrinus is reported as either pair- or family-living, with paternal care such as carrying grooming and defending young. Sleeping groups of adults of varying sexual composition have also been recorded. Most of the rainforest species and P. volans are solitary both while foraging and resting.

Deposit of feces on specific sites has been found in P. dahli, and a sternal gland is used by sternal rubbing in several species of Pseudocheirus. Acoustic communication seems to be of medium importance, with distress calls uttered by young in trouble, soft contact calls by family members of P. peregrinus, loud contact calls, possibly for spacing, as a "dusk" chorus of P. forbesi, and vocal recall of young from dangerous situations in P. peregrinus. There is no evidence of territorial defense in any species, even the solitary ones, except a certain spatial distribution pattern of P. volans that is more evenly distributed than statistically expected from randomness. This suggests at least active avoidance, or perhaps some sort of defense. All

species are mostly nocturnual. Pseudochirops archeri sometimes can be seen active during the day.

Feeding ecology and diet

Petauroides volans is a highly specialized folivore, who feeds about 90% of its diet on eucalyptus leaves. It relies on high nutrient species or growth stages, and seems to be able to actively select these high-quality leaves based on tree species and leaf age. All the remaining species, so-called ringtails, also are folivores, and at least some species, such as Pseudocheirus peregrinus, are also capable of eating high amounts of eucalyptus leaves. However, they mostly do not rely so heavily on eucalypts alone, eating buds, flowers and fruits of other plants, in the understory of eucalypt forests as well. All leaf-eating pseudocheirids are hindgut-fermenters, which means that in their large colon and cecum, a specialized community of bacteria and other microorganisms is kept to digest cellulose (plant cell walls cannot be digested by any animal). They are all capable, in their hindgut, to separate the contents into large particles, which are defecated rather quickly, and small particles, solubles and bacteria themselves. This mechanism serves to retain the more digestible parts and nitrogen-carrying bacteria. Ringtail possums also are caecotrophic; the colon contents are defecated separately, and ingested again to gain proteins and amino acids by foregut digestion. Eucalypt-feeding ringtails often show strong preferences for certain trees, and dislike for other trees of the same species. Subsequent chemical analysis revealed a higher proportion of toxic or unpalatable substances in the rejected individuals. They are, however, when not given a choice, capable of detoxifying the toxic plant secondary metabolites, though at a cost of higher energy and nitrogen requirements.

Reproductive biology

Mating systems of pseudocheirids, as already suggested by their diverse social organization, are rather variable. Several species are long-term monogamous, which may also include paternal care. Others, the solitary ones included, are polygamous, with evidence for shifts from monogamy to polygyny between years for the greater glider, depending on the food supply. Breeding in Petauroides is seasonal, one young per year being born in autumn to winter. The young stays in the pouch for 90–120 days, and is carried on the mother's back for another 90 days. Young become independent around 10 months of age, and sexually mature during their second year. The tropical ringtails, particularly those from New Guinea, seem to have no reproductive season. Consort relationships, an accompanying by a male for an estrous female for a few days, have been described for some species, nothing else is known about mating systems of the solitary ones. Number of young per litter is one or two, depending on the species, and it seems that, as far as known, the age of 120 days for leaving the pouch characterizes them all. Weaning occurs, again known only for

some species at 150–160 days (Pseudochirulus herbertensis) to 180 days (Pseudocheirus peregrinus). Females, at least in P. peregrinus, are capable of producing two litters per year. Longevity in the wild is approximately four to five years.

Conservation status

Several species of pseudocheirids are either widespread, and ecologically adaptable (e.g., P. peregrinus), or quite abundant in their current habitat, which is not under immediate threat. Others, however, are vulnerable due to a restricted area of distribution (e.g., some of New Guinean species, or the rock ringtail). Among the New Guinean species, several are unknown in status and biology. None of the potentially vulnerable species is currently protected under Indonesian or Papua law, and the system of proposed or established natural reserves may be inadequate to protect them, also because the reserves have been proposed without considering the needs of local people or animals themselves. Petauroides volans is considered vulnerable due to its dependence on old, hollow trees for nesting, and due to its patchy distribution even in prime habitat. Over 50% of the forest, even in areas where it is common, is never used, and over 60% of individuals used 9% of the available forest in one study. Logging of such areas has tremendous negative effects.

A different kind of threat is expected to arise over the next few years or decades. Due to global warming and increasing carbon dioxide (CO²) levels, eucalypts are expected to increase the level of toxins and antinutrients in their leaves (because these secondary metabolites are a common way of storing chemical waste in plants). It has been calculated that, given the current amount of increasing CO² levels, within the next 50 years most of Australian's eucalypt forests will be uninhabitable for leaf-eating species, such as greater gliders.

Significance to humans

Some of the larger New Guinean species are hunted for meat.

Species accounts

List of Species

Lemuroid ringtail

Hemibelideus lemuroides

taxonomy

Hemibelideus lemuroides (Collett, 1884), north Queensland, Australia.

other common names

English: Lemur possum; French: Ringtail lemurien; German: Lemur-Ringbeutler.

physical characteristics

Length 2.6–2.8 in (65–72 mm), weight 28.2–44.8 oz (800–1,270 g). Woolly coat is grey on back, yellow on belly, and brown on shoulders. Bushy tail has bare tip.

distribution

Atherton and Mount Carbine Tablelands, above 1,575 ft (480m), in North Queensland.

habitat

Mountain rainforest.

behavior

Arboreal, nocturnal, leaping vividly from tree to tree; monogamous pairs are formed and mostly observed in close proximity.

feeding ecology and diet

Leaf-eater (at least 37 species), but supplements its diet with flowers and fruits.

reproductive biology

Monogamous. One young per year, from August to November.

conservation status

Not threatened.

significance to humans

None known.

Greater glider

Petauroides volans

taxonomy

Petauroides volans (Kerr, 1792), Sydney, Australia. Two sub-species.

other common names

French: Phalanger volant geant; German: Riesengleitbeutler.

physical characteristics

Length 35.4–41.3 in (90–105 cm), weight 31.7–60.0 oz (900–1,700 g). Dark brown body with white underside. Gliding membrane from elbow to ankles. Long bushy tail.

distribution

Eastern Australia.

habitat

Sclerophyll forests, dry and wet, but no rainforest.

behavior

Gliding for up to 330 ft (100 m), capable of mid-glide turns (by using tail as a rudder) of up to 90°; as gliding membrane is only

from elbow, wrists are not extended but tucked under chin in flight. Solitary home range of males and females may overlap.

feeding ecology and diet

Folivore, only very limited amount of other plant parts.

reproductive biology

One young per year is born between March and June, stays in the pouch for 120 days, rides on mother's back for another three months. Usually monogamous.

conservation status

Vulnerable.

significance to humans

None known.

Green ringtail

Pseudochirops archeri

taxonomy

Pseudochirops archeri (Collett, 1884), north Queensland, Australia.

other common names

French: Ringtail vert, ringtail au pelage raye; German: Grüner Ringbeutler.

physical characteristics

Length 25.6–28.0 in (65–71 cm), weight 37.9–47.6 oz (1,075–1,350 g). Fur appears green due to thin bands of black, yellow, and white fur.

distribution

Upland rainforest in tropical northeastern Queensland coastal areas.

habitat

Rainforest.

behavior

Mostly nocturnal, arboreal animal probably solitary. Sometimes seen active during the day, rests on branches instead of in tree hollows. Adults seem not to vocalize at all. Young are carried on mother's back for longer than other ringtails, and follow her around at-heel afterwards.

feeding ecology and diet

Green ringtails eat leaves of rainforest trees, also of rather toxic species. This may be the reason why the young follows the mother for an extended period of time.

reproductive biology

Almost nothing is known except that normally only one young is around at a time.

conservation status

Not threatened.

significance to humans

None known.

Rock ringtail

Petropseudes dahli

taxonomy

Petropseudes dahli (Collett, 1895), Northern Territory, Australia.

other common names

English: Rock-haunting possum, rock possum; French: Ringtail des rochers; German: Felsenringbeutler.

physical characteristics

Length 20.9–25.2 in (53–64 cm), weight 45.2–70.6 oz (1,280–2,000 g).

distribution

Three isolated populations in northwestern Queensland, Northern Territory, and northern Western Australia.

habitat

Rocky areas.

behavior

Partly terrestrial, hiding and resting in crevices and under rocks during the day. During the night they emerge and climb trees to feed. Rock ringtails appear to live in extended family groups, up to seven animals have been seen together, including young of several developmental stages.

feeding ecology and diet

Leaves, flowers of trees and fruits are eaten of a variety of species.

reproductive biology

Normally one young per time is observed, and reproduction seems to be non-seasonal. Usually monogamous.

conservation status

Though not listed by the IUCN, considered vulnerable by some authors due to a contraction of range since discovery in 1890s.

significance to humans

None known.

Common ringtail

Pseudocheirus peregrinus

taxonomy

Pseudocheirus peregrinus (Boddaert, 1785), Queensland, Australia. Five subspecies.

other common names

English: Tasmanian ringtail, western ringtail, rufous ringtail; French: Ringtail commun; German: Gewöhnlicher Ringbeutler.

physical characteristics

Length 23.6–27.6 in (60–70 cm), weight 24.7–38.8 oz (700–1,100 g). Gray-brown fur with light underside. Tail is long and thin; end half is pale color.

distribution

Southwestern Australia coastal areas along eastern coast from Cape York to Southern Australia; Tasmania and Bass Strait islands.

habitat

All types of vegetation with dense shrubs and understory, from heathland to rainforest.

behavior

Noctural (mostly before midnight), building large nests from twigs and leaves (dreys), often several members of a family group building nests immediatly next to each other, or nesting together. Living in pairs or groups. Males take part in care of the young.

feeding ecology and diet

Leaves, fruits and flowers are eaten. Common ringtails can detoxify eucalypts. Coprophagy of cecum contents is common.

reproductive biology

Normally two young are born, between April and November. They leave the pouch within 120 days, are weaned at about 180 days and sexually mature within 12 months. Mating system is not known.

conservation status

Not threatened.

significance to humans

Suburban individuals can be a minor nuisance to gardeners by eating flowers, buds etc of ornamental plants (e.g., roses).

Lowland ringtail

Pseudochirulus canescens

taxonomy

Pseudochirulus canescens (Waterhouse, 1846), Irian Jaya, Indonesia. Five subspecies.

other common names

French: Ringtail à plaine; German: Tiefland-Ringbeutler.

physical characteristics

Length 15.0–17.0 in (38–43 cm), weight about 12.3 oz (350 g).

distribution

Lowland areas in all New Guinea.

habitat

Lowland and foothill rainforest, which is an exception for New Guinean species of this family.

behavior

Probably solitary. Noctural, arboreal.

feeding ecology and diet

Herbivore, folivore.

reproductive biology

Nothing is known.

conservation status

Not threatened, but rare all over its range.

significance to humans

None known.

Herbert River ringtail

Pseudochirulus herbertensis

taxonomy

Pseudochirulus herbertensis (Collett, 1884), Queensland, Australia.

other common names

French: Ringtail á Herbert; German: Herbert Ringbeutler.

physical characteristics

Length 24.4–30.3 in (62–77 cm), weight 24.7–51.1 oz (700–1,450 g). Dark fur with white belly. Long thin tail with dark hairs.

distribution

Limited range in tropical Queensland mountains.

habitat

Upland rainforest.

behavior

Noctural and solitary animals, normally resting in tree hollows, but also capable of building tree nests. Young ride on mother's back only for a short time, and are then left in the nest.

feeding ecology and diet

Leaves, fruits, and flowers are eaten.

reproductive biology

Juvenile females have four teats, adults only two. Normally two young are born, mostly between May and June. They leave the pouch after about 120 days and are weaned within 150 to 160 days. Sexual maturity is reached by about 12 months. Mating system is not known.

conservation status

Not threatened.

significance to humans

None known.

Pygmy ringtail

Pseudochirulus mayeri

taxonomy

Pseudochirulus mayeri (Rothschild and Dollman, 1932), Irian Jaya, Indonesia.

other common names

French: Ringtail mineur; German: Zwergringbeutler.

physical characteristics

Length 13.4–15.0 in (34–38 cm), weight 3.7–7.3 oz (105–206 g).

distribution

Central Cordillera of New Guinea, at higher than 4,920 ft (1,500 m).

habitat

Moss forests, most abundant at 6,560 ft (2,000 m) and above.

behavior

Nocturnal, during the day they seem to be partly torpid, as they are rather sluggish and timid when caught.

feeding ecology and diet

Possibly too small to be an effective folivore; local people report it eats moss and lichen. Captive individual refused leaves, but took sugar water.

reproductive biology

Nothing is known, except one young is seen at a time.

conservation status

Not threatened.

significance to humans

None known.

Resources

Books

Cork, Stephen J., and William J. Foley. "Digestive and

Metabolic Adaptations of Arboreal Marsupials for Dealing with Plant Antinutrients and Toxins." In Marsupial Biology—Recent Research, New Perspectives, edited by Norman Saunders and Lyn Hinds. Sydney: UNSW Press, 1997.

Flannery, Tim F. Possums of the World. Chatswood, Australia: Geo Productions, 1995.

Goldingay, Ross L. "Gliding Mammals of the World. Diversity and Ecological Requirements." In Biology of Gliding Mammals, edited by Ross L. Goldingay and John S. Scheibe. Fürth: Filander Verlag, 2000.

Kennedy, Michael, ed. Australasian Marsupials and Monotremes—An Action Plan for their Conservation. Gland, Switzerland: IUCN Publication Department, 1992.

Strahan, Ron, ed. The Australian Museum Complete Book of Australian Mammals. Sydney: Australian Mammals; Sydney: Australian Museum, 1995.

Winter, John W. "Australasian Possums and Madagascan Lemurs." In Comparison of Marsupial and Placental Behaviour, edited by David B. Croft and Udo Ganslosser. Fürth, Germany: Filander Verlag, 1996.

Udo Gansloßer, PhD