| abstract | Australolaelaps greeni, n.sp., is described from the peculiarly Tasmanian Bettongia cuniculus (Potoroinae, Macropodidae), and Haemolaelaps calypso, n.sp., from Petaurus breviceps (Phalangerinae, Phalangeridae), which occurs throughout eastern Australia and New Guinea. The comparative anatomy of the species of Trichosurolaelaps and Australolaelaps is tabulated, all being parasites of recent syndactylous marsupials in the Australian zoogeographical region. Both genera are recognized as valid. The former comprises two species-grooups, one from peramelids and one from phalangerids and Hypsiprymnodon, the sole member of an aberrant macropodid subfamily with traces of its scansorial ancestry. The latter comprises parasites of the remaining macropodid subfamilies (Potoroinae and Macropodinae) |