BABESIA-THYLACIS (APICOMPLEXA, BABESIIDAE) IN A NORTHERN QUOLL, DASYURUS-HALLUCATUS (MARSUPIALIA, DASYURIDAE), FROM WESTERN-AUSTRALIA

Babesia thylacis Mackerras, 1959, is provisionally identified and desc ribed from a stained blood smear obtained from a female northern quoll , Dasyurus hallucatus (Gould, 1842), captured on the Mitchell Plateau, Kimberley, Western Australia. This represents the third known natural host of this parasite and the first published account of its presence in Western Australia. Babesia thylacis has so far been found only in small carnivorous or insectivorous marsupials from Australia. Parasite morphology is characteristically pleomorphic, ranging from small amoe boid organisms to fully grown, pyriform protozoans, either single or p aired, 2-4 by 1-1.5 mu m. In most cases, mature parasites contain a pr ominent vacuole with a rounded nucleus either centrally or terminally located. Nuclear material that was elongated and stretched out along t he periphery of some organisms was not uncommon. Infected red blood ce lls commonly contained only 1 parasite and occasionally paired merozoi tes.