NOTES ON THE PHALANGERID MARSUPIAL GENUS SPILOCUSCUS, WITH DESCRIPTION OF A NEW SPECIES

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