The scaly-tailed possum (''Wyulda squamicaudata'') is found in northwestern
Australia
Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...
, where it is restricted to the
Kimberley
Kimberly or Kimberley may refer to:
Places and historical events
Australia
Queensland
* Kimberley, Queensland, a coastal locality in the Shire of Douglas
South Australia
* County of Kimberley, a cadastral unit in South Australia
Ta ...
.
They are light grey over most of the body and have relatively short ears and muzzle. The mostly hairless tail is able to curl around the branches of trees as the possum forages for food, its grasp is aided by rasp-ilke scales and is strong enough to hold its own weight. The species favours complex rocky terrain with dense thickets of vines and the fruiting trees that provide much of their diet.
Taxonomy
The new species was presented to the
Royal Society of Western Australia
The Royal Society of Western Australia (RSWA) promotes science in Western Australia.
The RSWA was founded in 1914, and also gained the "Royal" name in the same year. It publishes the ''Journal of the Royal Society of Western Australia'', and has ...
in 1918 by the biologist
Wilfred Backhouse Alexander
Wilfrid Backhouse Alexander (4 February 1885 – 18 December 1965) was an English ornithologist and entomologist. He was a brother of Horace Alexander and Christopher James Alexander.
Alexander was born at Croydon in Surrey, England in 1885 ...
, while he was employed by the
Western Australian Museum
The Western Australian Museum is a statutory body, statutory authority within the Culture and the Arts Portfolio, established under the ''Museum Act 1969''.
The museum has six main sites. The state museum, WA Museum Boola Bardip, is located i ...
, and published in the society's journal in the same year. The description was accompanied by a reproduction of a painting by
George Pitt Morison, and two photographs of the specimen's skull were also included.
The
holotype
A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...
was reported to have been collected in the Kimberley region at Violet Valley Station, and forwarded to
Walter Kingsmill who presented the specimen to the
Perth Zoological Gardens.
Alexander assigned the species to a new genus of the
phalangerid family, ''Wyulda'', deriving the name from an indigenous word used by the people at
Lyons River for the local and common possum; the pronunciation provided by the author is "weeoolda".
Aside from scaly-tailed possum, the recorded names for the species include ilangurra and yilangal (the latter by the
Wunambal people of
Mitchell Plateau). The describing author proposed the common name scaly-tailed opossum, but gave an alternative as scaly tailed phalanger if the use of the term for the American marsupial
opossum
Opossums () are members of the marsupial order Didelphimorphia () endemic to the Americas. The largest order of marsupials in the Western Hemisphere, it comprises 126 species in 18 genera. Opossums originated in South America and entered North A ...
was considered inappropriate.
As the common name implies, its distinguishing feature is a hairless, scaly tail.
Description
An arboreal species of the
Phalangeridae
The Phalangeridae are a family of mostly nocturnal marsupials native to Australia, New Guinea, and Eastern Indonesia, including the cuscuses, brushtail possums, and their close relatives. Considered a type of possum, most species are arboreal, a ...
family with short ears and muzzle, and a body with a stocky build. The total length of the head and body is , the distinctive tail is , and their weight ranges from . The coloration of the
pelage
A fur is a soft, thick growth of hair that covers the skin of almost all mammals. It consists of a combination of oily guard hair on top and thick underfur beneath. The guard hair keeps moisture from reaching the skin; the underfur acts as an ...
is light grey with brown flecking over the upper parts, becoming a rufous colour toward the base of tail and over the rump; an indistinct mid-line extends along the back of the possum, from the tail to between the eyes. The fur at the underside is creamy white. A densely furred region extends a short distance over the base of the tail, which is otherwise naked. ''Wyulda squamicaudata'' is distinguished by rasp-like scales over the surface of their strongly prehensile tail.

''Wyulda squamicaudata'' is a slow growing species, the rate of increase in skull length for juveniles is 0.26 mm per day. The weight when the female reaches a reproductive age at two years old is . less than the weight range of fully mature individuals. There is no difference in weight between genders and is not known to be seasonally variable.
The species has been allied within the family
Phalangeridae
The Phalangeridae are a family of mostly nocturnal marsupials native to Australia, New Guinea, and Eastern Indonesia, including the cuscuses, brushtail possums, and their close relatives. Considered a type of possum, most species are arboreal, a ...
as a relation of other Australasian genera, the cuscuses ''
Phalanger'' and brushtail possums ''
Trichosurus''.
Superficially similar to other possum species, the observable differences from the commonly found possum ''
Trichosurus vulpecula'' are the fox-like face, furry tail and larger of that species. Another rock inhabiting possum found in the region, the ringtail species ''
Petropseudes dahli'', has fur covering half the tail, patches of white near the ears, and a steep forehead and pointed muzzle when observed in profile.
The parasites known to use ''Wyulda squamicaudata'' as a host include internal species, the cestode ''
Bertiella trichosuri'' also found in possums of ''
Trichosurus'', ''
Adelenema trichosuri'' and a species of ''
Austrostrongylus'', a genus associated with wallabies.
Behaviour
''Wyulda squamicaudata'' is a nocturnal animal that usually occurs alone. Their behaviour is discreet and shy while foraging in trees or over rocks. They demonstrate great agility when climbing, assisted by a prehensile tail that is strong enough to support themselves from a branch while reaching for leaves and other food.
Reproduction takes place during the dry season of north west Australia, usually between March and August and occasionally giving birth later in that season. The maternal rearing period of the young includes 150 to 200 days within the pouch and another eight months to become independent of the mother; reproductive maturity for the female is reached after two years.
Usually found in denser wooded areas, ''W. squamicaudata'' may be seen foraging in open areas. The diet largely includes leaves, seeds, roots and flowering parts of plants, although nuts and insects are also consumed.
A study of the species found that up to three quarters of the diet is composed of fruits.
Distribution and habitat
The possum has a limited range and is found in the high rainfall near coastal regions of the north Kimberley between
Yampi Sound and
Kalumburu, and a smaller population that occurs inland in the east Kimberley at Emma Gorge.
''Wyulda squamicaudata'' is most widely reported across the
Artesian Range, where it is moderately common. Populations also inhabit
Bigge Island and
Boongaree Island. The preferred
habitat
In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...
of this animal is
sandstone
Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...
based
woodland
A woodland () is, in the broad sense, land covered with woody plants (trees and shrubs), or in a narrow sense, synonymous with wood (or in the U.S., the '' plurale tantum'' woods), a low-density forest forming open habitats with plenty of sunli ...
s where it can shelter in rock piles and fissures and feed in the trees.
They are associated with denser vegetation over rocks and boulders that provide daytime shelter and refuge, often thickets of vines rather than the closed mangrove and open woodlands favoured by ''
Trichosurus arnhemensis
The northern brushtail possum (''Trichosurus arnhemensis'') is a nocturnal marsupial inhabiting northern Australia. The northern brushtail possum is sometimes considered a species; however, more often than not is considered a subspecies of the ...
''.
The species is restricted in its range by the complexity of a rocky habitat, providing more dens and refuge from fires in the surrounding landscape.
The species' type location is in the eastern Kimberley, at Violet Valley near
Warmun, but most records are of their occurrence are in the north-west of the region. The specimen obtained in 1917 was the only record of the possum in east Kimberley region until 2010, when they were found occurring at Emma Gorge in the
Cockburn Range. The eastern and north-western groups may be geographically isolated, but this has not been confirmed by a broad survey of the Kimberley region.
It is present in the
Charnley River–Artesian Range Wildlife Sanctuary in the
Kimberley
Kimberly or Kimberley may refer to:
Places and historical events
Australia
Queensland
* Kimberley, Queensland, a coastal locality in the Shire of Douglas
South Australia
* County of Kimberley, a cadastral unit in South Australia
Ta ...
region of WA.
''Wyulda squamicaudata'' has disappeared at some locations, where they are assumed to have succumbed to frequent and higher intensity fires and predation by feral cats. An outlying occurrence in Broome reported in 1970 is thought have been a displaced individual.
The
northern brushtail possum ''Trichosurus arnhemensis'' occurs in the same region as this species, but does not appear to share the same habitat.
Conservation
The IUCN Red List assigns a conservation status of near threatened for the species. The population was assessed in 2014 as numbering between 5000 and 10,000 with evidence that it is decreasing.
References
External links
Marsupial Society of Australia article on scaly-tailed possum{{Taxonbar, from=Q1762917
Mammals of Western Australia
Marsupials of Australia
Possums
Mammals described in 1918
Taxa named by Wilfred Backhouse Alexander