DNA Sequence Evidence for Placement of the Ground Cuscus, Phalanger gymnotis, in the Tribe Phalangerini (Marsupialia: Phalangeridae)

Abstract

A region of mitochondrial DNA, including the 3′ end of tRNA phenylalanine, the complete 12S rRNA and tRNA valine genes, and the 5′ end of 16S rRNA, was sequenced for four phalangerids and one burramyid; additional marsupial sequences were extracted from GenBank. Parsimony, minimum evolution, and maximum likelihood analyses show that the ground cuscus, Phalanger gymnotis, groups with the tribe Phalangerini, not with the tribe Trichosurini as had been suggested on the basis of certain morphological characters. This result is in agreement with an earlier study using DNA hybridization and is supported by some morphological evidence as well. We conclude that the character states that link the ground cuscus with the Trichosurini are the result of convergence, and therefore the placement of several other species in the trichosurin genus Strigocuscus based on the same characters should be reconsidered. The hypothesized close relationship of two fossil taxa, Strigocuscus reidi and S. notialis, to Phalanger gymnotis is also questionable because the fossils do not share morphological synapomorphies that link the ground cuscus to the Phalangerini.