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-cycles of various Digenea. However, in many digenean species, the larvae lack distinctive morphological features and it is impossible to establish the affiliation between the larval and adult stages by using morphological criteria. Molecular methods, based on DNA sequencing or PCR–restriction fragment length polymorphism analysis, can offer a new tool for larval-stage identification. In this study, the sequences of internal transcribed spacer of the ribosomal DNA were used to identify the cercariae of three out of five species of the family Mesometridae ( Centroderma spinosissima, Elstia stossichianum and Wardula capitellata). The three species differ from one another by number of repeats in the region of internal transcribed spacer 1. The phylogeny of Mesometridae was inferred from their internal transcribed spacer ribosomal DNA sequences. The PCR-linked restriction fragment length polymorphism approach was developed for future life-cycle and ecological studies of this family.