Spilocuscus

Abstract: We sequenced the 12S rRNA gene of 2 elusive and morphologically plesiomorphic species of phalanger: the small Sulawesi cuscus (Strigocuscus celebensis—Gray, 1858) and the Sulawesi bear cuscus (Ailurops ursinus— Temminck, 1824). The sequences were integrated with previously existing data on the same gene in other species of phalangerids, as well as newly derived data from Wyulda Alexander, 1918. In contrast to current wisdom, we resolve S. celebensis not as a member of the tribe Trichosurini, but rather as a taxon sister to Ailurops in a reconstituted Ailuropinae in turn successively sister to Phalangerinae. Examination of our data supports an evolutionary origin for the family approximately 34 million years ago (mya), in the northwestern region of the Sahul Shelf, the continental mass underlying Australia and New Guinea. The radiation of the most plesiomorphic genera in the family, Trichosurus and Wyulda, is restricted to that region. S. celebensis, resolved as sister to A. ursinus in a clade ingroup to trichosurines, diverged from remaining ingroup lineages between 21.1 and 23.3 mya, a time when Sulawesi was available for colonization and sea currents would have enhanced the colonization potential from the east of Sulawesi and neighboring islands. We recommend Trichosurinae as a subfamilial level entity on par with Ailuropinae and Phalangerinae, circumscription of Trichosurinae to Trichosurus and Wyulda, and removal of Strigocuscus into Ailuropinae, leaving only Phalanger and Spilocuscus in Phalangerinae.

Abstract: DNA-hybridisation experiments, involving seven species of Phalangeridae and two outgroup taxa in a complete 9 x 9 matrix, unequivocally placed the bear cuscus, Ailurops ursinus, nearest to the Phalangerini (Phalanger and Spilocuscus), with Trichosurini (Trichosurus) sister to both; and confirmed earlier molecular studies indicating that the ground cuscus, Strigocuscus gymnotis, is not a trichosurin but is closest to Phalanger. Our results thus conflict with the most thorough cladistic-anatomical study of phalangerids, which placed the bear cuscus outside all other Phalangeridae as the sole living member of Subfamily Ailuropinae; instead, we suggest that Ailurops should be considered representative of a tribe of Phalangerinae, Ailuropini, while Trichosurus (and presumably Wyulda, which was not examined here, as well as fossil Strigocuscus) would be removed from Phalangerinae and be considered a second subfamily of Phalangeridae, Trichosurinae, limited to Australia. Our estimate of the time of divergence of Ailurops and other phalangerines is about 16 myrbp; of Trichosurinae and Phalangerinae, about 21 myrbp. Thus, a single Early Miocene vicariant event between Australia and Papua New Guinea, which isolated phalangerines in the latter region, followed by dispersal of the included ailuropins to (or vicariant separation on) Sulawesi, would be sufficient to account for family-level cladogenesis in Phalangeridae.

Abstract: Rates of metabolism and body temperatures were measured as a function of ambient temperature in 6 species of cuscuses, including 5 species of Phalanger and 1 species of Spilocuscus from Papua New Guinea. These species had basal rates that are typical of marsupials. Basal rate of metabolism correlated with activity level, with active species having basal rates that averaged 18% greater than inactive species. Body mass and activity level accounted for 96.6% of the variation in phalangerid basal rates. The uniformity in marsupial basal rate, independent of body mass, reflects a form of reproduction that cannot exploit high basal rates. Montane species tended to have lower thermal conductances than generally found in species limited to low altitudes.

Abstract: A new small-bodied species of spotted cuscus is described from Biak and Supiori, neighboring oceanic islands in Cenderawasih Bay, northwest New Guinea. The nonvolant mammal fauna of Biak-Supiori is almost entirely endemic. The geographic origin of another insular species of the genus (Spilocuscus kraemeri) is also discussed: S. kraemeri is a distinctive species known only from the Admiralty Islands but, due to its putative absence from the fossil record of those islands, it is thought to have been introduced there from an unknown source population in prehistoric times. Based on new evidence, we suggest that kraemeri is either native to the Admiralty Islands, or originally differentiated on the large island of New Britain in the Bismarck Archipelago. The spotted cuscuses (the phalangerid genus Spilocuscus Gray, 1862) comprise a group of colorful, medium sized, arboreal frugivore-folivores endemic to tropical forests in the Australo-Papuan region. The distribution of the genus includes the lowlands of New Guinea, tropical northeastern Australia, and many Melanesian islands, including several New Guinean land bridge islands (Yapen, Misool, Salawati, and the Aru Islands) and several oceanic islands near New Guinea, including the Bismarck Archipelago, Waigeo and Batanta, BiakSupiori, Numfoor, and the Kai Islands (Flannery 1994). The range of 1 species of the genus (S. maculatus chrysorrhos) also extends to the island of Salayer south of Sulawesi (as a result of human-sponsored introduction—George 1987), and to the Central Moluccas (Seram, Ambon, Buru, and the Banda Islands) where it might be either native or introduced (Flannery 1995b; Helgen 2003). Drawing on their studies of features of the cranium, dentition, and integument, Flannery et al. (1987) and George (1987) argued that species of Spilocuscus should be separated generically from those ofPhalanger (sensu stricto, i.e., with content as defined by Groves [in press]), with which they were previously considered congeneric (Feiler 1978; Laurie and Hill 1954; Thomas 1888; Tate 1945). The monophyly of Spilocuscus and its generic-level