A REVIEW OF THE HELMINTH-PARASITES OF AUSTRALIAN RODENTS

The most recent catalogue of the internal parasites of Australian rode nts is that prepared by Mackerras in 1958. She listed 89 native rats b elonging to 18 genera of which 8 species had had parasites recorded fr om them. There has been very little progress made since that time. The most recent catalogue of Australian mammals lists 57 extant species o f rodents in 14 genera. Helminths have now been reported from 16 of th ose species. The helminth communities occurring in only two rodent hos ts, Rattus fuscipes and Hydromys chrysogaster, have been studied in de tail. The contrast in helminth communities from these two hosts, one d ominated by trematodes and the other by nematodes, may reflect not onl y differences in the ecology and geographic distribution of both host and parasite but also differences in the origins of the two subfamilie s, the Hydromyinae and the Murinae, to which they belong. An analysis of the helminth communities of native rodents suggested patterns of sp eciation of the helminths that included co-evolution with host species -groups, and host switching from the Hydromyinae to the Murinae as wel l as the reverse. Species such as the cestode Hymenolepis diminuta and the nematode Heterakis spumosa may have been introduced or re-introdu ced by the recent arrival of cosmopolitan Rattus species, and species such as Paramelistrongylus skedastos have transferred from marsupial h osts.