A DNA-based demonstration of a three-host life-cycle for the Bivesiculidae (Platyhelminthes: Digenea).
Immature bivesiculid trematodes collected in Australia from the intestine of Thalassoma lunare (Labridae) were shown to be morphologically consistent with adults of Bivesicula claviformis from Epinephelus fasciatus (Serranidae). In addition, the immature bivesiculids had the same sequence for the second internal transcribed spacer of the ribosomal DNA. Comparison with 3 other species of Bivesiculidae showed differences of between 23 and 30%. It is suggested that these results indicate that bivesiculids may have 3-host life-cycles in addition to the 2-host life-cycles that have been demonstrated previously. It is suggested that the 3-host life-cycle enables bivesiculids to infect large carnivorous fishes.