Biodiversity and parasites of wildlife: Helminths of Australasian marsupials

•The helminth fauna of Australasian wildlife is extremely diverse and highly endemic but is as yet poorly documented.•Obstacles inhibiting full documentation include limited access to uncommon host species and geographical limitations.•Other obstacles include the presence of cryptic species, and the difficulty of locating small parasites or those found in various organs of the body outside the gastrointestinal tract.•Current optimistic global projections concerning the documentation of life on earth may not hold for specific groups such as the helminths of Australasian wildlife.

Despite current attempts to document the extent of biodiversity on Earth, significant problems exist in fully documenting the helminth parasites of wildlife. Using the Australasian marsupials as an example, we examine some of these difficulties, including challenges in collecting uncommon host species, the ongoing description of new species of marsupials, the presence of cryptic species, and the decline in taxonomic expertise in Australia. Although optimistic global predictions have been made concerning the rate of discovery and description of new species of animals, these predictions may not apply in the case of specific groups of animals such as the Australasian marsupials.