Gallegostrongylus australis n. sp (Nematoda : Angiostrongylidae) from Muridae in Australia, with zoogeographical considerations

Gallegostrongylus australis n, sp. (Nematoda: Angiostrongylidae) is describ ed from subpleural nodules in the lungs of Rattus fuscipes, R, lutreolus an d Mus domesticus in Australia. it is distinguished from G. andersoni occurr ing in gerbillids in West Africa by the shorter lengths of spicules and gub ernaculum, and from G. ibicensis occurring in microtids and murids in Spain by the greater lengths of spicules and gubernaculum and the shorter distan ces from vulva and from anus to the caudal extremity of females. The parasi te has been found only in 16 of 4,227 (prevalence 0.38%) animals representi ng at least 28 species of native and three species of introduced murid rode nts throughout Australia. The genus Gallegostrongylus may be an old one, po ssibly originating in rats. By railing and/or human activities the parasite appears to have been distributed around the world where ii has encountered suitable intermediate hosts and available niches for colonisation of new d efinitive hosts. Consequently, morphologically similar but biologically dis tinct species have evolved in rodent hosts in West Africa, the western Medi terranean, and Australia.