The taxonomy of leeches is very incomplete. Many now face extinction., but very little is known about either the diversity or susceptibility of leeches to environmental changes brought about by human activities, particularly in the Australasian region. Keys and species lists that are currently available are limited by their incomplete nature and restricted availability and are not widely used. The resulting taxonomy has led to confusion, particularly among non-specialists, regarding the relationships of leeches.
Three new taxonomic keys have here been compiled tor the terrestrial and freshwater Euhirudinea of Australia, New Zealand, New Guinea and Oceania. The first is a key to the recognised families and subfamilies of Euhirudinea, the second is a key to genera and the last is a key to species. A species checklist with distribution information has also been put together and is based on both published and new unpublished data collected by various Australian research institutions and by the author.