PARENT SESSION

Systematics/Zoogeography 5 -- Session Chair: Theresa Spradling-- Van Duzer Theater

EVOLUTIONARY RELATIONSHIPS AMONG PHALANGERIDS, (DIPROTODONTIA: PHALANGERIDAE), INFERRED FROM MITOCHONDRIAL DNA (12S RRNA) SEQUENCE DATA. Luis A. Ruedas^1,2 and Juan Carlos Morales³. ¹ Department of Biology, Portland State University, 1719 SW 10th Avenue, Portland, Oregon, USA; ² Museum of Vertebrate Biology, Portland State University, 1719 SW 10th Avenue, Portland, Oregon, USA; ³ Center for Environmental Research and Conservation, Columbia University -- MC 5557, Schermerhorn Ext., 10th floor; 1200 Amsterdam Avenue, New York, New York, USA.

ABSTRACT- We sequenced the 12S rRNA gene of an elusive and morphologically plesiomorphic species of phalanger: the Small Sulawesi Cuscus, Strigocuscus celebensis (Grey, 1858), as well as that of the Sulawesi Bear Cuscus, Ailurops ursinus (Temminck, 1824), and the scaly–tailed possum, Wyulda squamicaudata (Alexander, 1918). The sequences were integrated with previously existing data on the same gene in other species of phalangerids. In contrast to current wisdom, we resolve Ailurops not as the basal subfamilial taxon in the family, but rather as a taxon basal to Phalangerinae and sister to Strigocuscus, the latter now excised from the tribe Trichosurini. Our data support an evolutionary origin for the family ca. 42 million years ago, in the northwestern region of the Sahul Shelf, the continental mass supporting Australia and New Guinea. The radiation of the most plesiomorphic taxa in the family almost all appear restricted to that region, or islands once constituting that region. The Sulawesi phalangerids diverged from remaining phalangerin lineages between 25.7 – 29.1 MYBP, 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. While heterodox, our novel hypothesis is biogeographically consistent. This conception of Phalangeridae will require taxonomic review, as the traditionally accepted subfamilial designations no longer are supported.

KEY WORDS: Australo-Pacific, evolution, Phalangeridae, biogeography