MOLECULAR SYSTEMATICS OF MUS CROCIDUROIDES, AN ENDEMIC MOUSE OF SUMATRA (MURIDAE, RODENTIA)

Complete sequences of the mitochondrial 12S rDNA gene were obtained in 11 taxa of Muridae in order to ascertain the molecular systematics of Mus crociduroides, an endemic mouse from the island of Sumatra. Parsi mony and distance analysis on different kinds of nucleotide changes (t ransitions, transversions, insertions and deletions) all suggest that Mus crociduroides clusters with Mus pahari, both species belonging to the subgenus Coelomys. These data provide confirmation for the traditi onal hypothesis based on morphological characters. The branching patte rn between the four subgenera of mice (Mus, Pyromys, Coelomys, and Nan nomys) could not be solved, probably due to insufficient taxonomic and genetic samplings. All molecular results do sustain the monophyly of the genus Mus sensu late when compared to African Murinae - Mastomys e rythroleucus and Hylomyscus stella -. The pattern of molecular evoluti on of the 12S rDNA gene observed in murid rodents is peculiar because the transitions: transversions ratio is about one, to the contrary of what is observed in other mammals differing by the same range of genet ic divergence, where transitions are much more numerous than transvers ions.