Petropseudes dahlii (Collett, 1895)

Russell A. Mittermeier & Don E. Wilson, 2015, Pseudocheiridae, Handbook of the Mammals of the World – Volume 5 Monotremes and Marsupials, Barcelona: Lynx Edicions, pp. 498-530 : 528

15.

Rock Ring-tailed Possum

Petropseudes dahlii

French: Possum des rochers / German: Felsenringbeutler / Spanish: Falangero rupicola de ¢ ola anillada

Other common names: Rock Possum, Rock-haunting Ringtail, Rock Ringtail Possum

Taxonomy. Pseudocheirus dahlii Collett, 1895 ,

“ Mary River , North Australia (13° 380° S. /Iat. 131° 30’ E. Long.).”

This species is monotypic.

Distribution. Endemic to N Australia, with two main populations, one in the Kimberley region of Western Australia that extends into W Northern Territory and a second from NC Northern Territory to Boodjamulla (= Lawn Hill) National Park in NW Queensland; also present on Groote Eylandt I.

Descriptive notes. Head-body 32-39 cm, tail 20-26 cm; weight 1.3-2 kg. The Rock Ring-tailed Possum has a stocky build and small ears. General coloration is ginger to gray, with a cream underbelly, and a pale cream patch occurs over each eye. A dark dorsal strip runs from nose to base of tail. Terminal part oftail is thinly furred; the only other species with a tail like this is the Coppery Ring-tailed Possum ( Pseudochirops cupreus ).

Habitat. Obligate in deeply fissured rock outcrops and large boulders in the Kimberley Region of Western Australia, Arnhem Land and Groote Eylandt in the Northern Territory, and the Lawn Hill Gorge area in north-western Queensland.

Food and Feeding. The Rock Ring-tailed Possum feeds on a variety of eucalypt tree species including blossoms of Darwin woollybutt ( Eucalyptus miniata) and Darwin stringybark (FE. tetrodonta) and fruits of Terminalia (Combretaceae) and Zyziphus ( Rhamnaceae ). They are also known to eat leaves of Acacia difficilis ( Fabaceae ), Darwin woollybutt, ironwood (Erythophleuwm chlorostachys, Fabaceae ), gulf or bill goat plum (7erminalia carpentariae, Combretaceae ), and Xanthostemon umbrosus ( Myrtaceae ).

Breeding. Reproduction of the Rock Ring-tailed Possum appears to be seasonal, with young observed with their mothers in March, July, August, and September.

Activity patterns. The Rock Ring-tailed Possum is strictly nocturnal. Individuals close to rocky areas immediately rush to the ground to shelter among boulders and crevices when alarmed, but if farther away from cover, they will freeze.

Movements, Home range and Social organization. The Rock Ring-tailed Possum is unlike most other ring-tailed possums in that it is mostly terrestrial and highly social. They den in rocky outcrops and undertake nightly activities in social family groups that stay in contact with an extensive communication system. Adults of both sexes scent-mark using caudal glands, with or without rump movement. Substrates that are scent-marked include rocks, trees (branches and trunks), and termite mounds. Scent marking can be very obvious (such as on rocky outcrops) and may be produced to provide information on reproductive status and age, resource defense, and intragroup communication, or to assist with navigation through rocky outcrops. While undertaking nightly foraging and social behaviors, groups traverse home ranges of 0-5-1-2 ha. Both sexes have the same size home ranges. The majority of Rock Ring-tailed Possums live in cohesive groups of 2-9 individuals that consist of a male-female pair and their young, which suggests they use an obligate monogamous mating system. Different groups maintain non-overlapping home ranges with long-term consorts and young sharing dens. Male Rock Ring-tailed Possums contribute more than females to maintaining the pair bond, but they contribute equally to parental care. Both parents also use bridge formations, using their bodies’ to link over gaps so that the young can climb over. They also engage in embracing, “marshaling” of young, sentinel behavior, and “tail beating.” Both sexes produce a range of vocalizations, including calls that are directed to other possum groups, contact calls between group members, and alarm calls, which are often accompanied by an audible tail beating against a branch or rock. When a group is foraging, one individual appears to be on guard and vocalizes if there is danger. Adult and young individuals use several calls in different contexts. These include alarm calls, calls directed at other groups, contact calls when individuals are separated from members of the group (5-20 m), a close-contact call where individuals are less than 1 m away, and a protection call by a mother of pouch young when group members threatened her balance on a branch.

Status and Conservation. Classified as Least Concern on The IUCN Red List. Although there are currently no major known threats to the Rock Ring-tailed Possum,its habitat is specialized, and many populations are isolated.

Bibliography. Burbidge, Woinarski, Winter & Runcie (2008), Couper & Hoskin (2008), Runcie (2000a, 2000b, 2004), Webb, M.J. et al. (2008).

Figures

13. Western Ring-tailed Possum (Pseudocheirus occidentalis), 14. Eastern Ring-tailed Possum (Pseudocheirus peregrinus), 15. Rock Ring-tailed Possum (Petropseudes dahl), 16. D’Albertis’s Ring-tailed Possum (Pseudochirops albertisii), 17. Green Ring-tailed Possum (Pseudochirops archeri), 18. Plush-coated Ring-tailed Possum (Pseudochirops corinnae), 19. Reclusive Ring-tailed Possum (Pseudochirops coronatus), 20. Coppery Ring-tailed Possum (Pseudochirops cupreus)

Distribution. Endemic to N Australia, with two main populations, one in the Kimberley region of Western Australia that extends into W Northern Territory and a second from NC Northern Territory to Boodjamulla (= Lawn Hill) National Park in NW Queensland; also present on Groote Eylandt I.