MITOCHONDRIAL ND1 GENE-SEQUENCES USED TO IDENTIFY ECHINOSTOME ISOLATES FROM AUSTRALIA AND NEW-ZEALAND

Echinostomes were collected in Australia and New Zealand as cercariae, metacercariae or adults. Using DNA sequences from the mitochondrial N D1 gene Echinostoma revolutum and Echinostoma paraensei were discovere d in Australia. The presence of a further five, as yet unidentified, e chinostome species was inferred in Northern Australia and a further is olate, closely allied to E. revolutum, occurs in New Zealand. ND1 sequ ences of species within the genus diverge from each other by 9.6-30.8% . Sequence divergence levels among strains within a single species are 0-3.6%. The phylogenetic tree produced from the Australasian isolates , in addition to species described previously, identifies the 37-colla r-spine species as a well supported monophyletic group. The five unide ntified Australian species cluster away from the 37-collar-spine group . These unidentified species appear to divide further into >37-collar- spine and <37-collar-spine clusters. Three strains of E. revolutum, co llected as metacercariae from snails, were identified from two ponds l ocated 6km apart. Two of these strains may be cycling through a planor bid snail, Glyptophysa sp., as first intermediate host; however, this hypothesis could not be confirmed as specimens could not be obtained t o match sequences between larvae and adults. (C) 1998 Australian Socie ty for Parasitology. Published by Elsevier Science Ltd.