USE OF THE ITS RDNA FOR ELUCIDATION OF SOME LIFE-CYCLES OF MESOMETRIDAE (TREMATODA, DIGENEA)

Identification of larval stages is crucial for elucidating the life-cy cles of various Digenea. However, in many digenean species, the larvae lack distinctive morphological features and it is impossible to estab lish the affiliation between the larval and adult stages by using morp hological criteria. Molecular methods, based on DNA sequencing or PCR- restriction fragment length polymorphism analysis, can offer a new too l for larval-stage identification. In this study, the sequences of int ernal transcribed spacer of the ribosomal DNA were used to identify th e cercariae of three out of five species of the family Mesometridae (C entroderma spinosissima, Elstia stossichianum and Wardula capitellata) . The three species differ from one another by number of repeats in th e region of internal transcribed spacer 1. The phylogeny of Mesometrid ae was inferred from their internal transcribed spacer ribosomal DNA s equences. The PCR-linked restriction fragment length polymorphism appr oach was developed for future life-cycle and ecological studies of thi s family. (C) 1998 Australian Society for Parasitology. Published by E lsevier Science Ltd. All rights reserved.