A DNA-BASED DEMONSTRATION OF A 3-HOST LIFE-CYCLE FOR THE BIVESICULIDAE (PLATYHELMINTHES, DIGENEA)

Immature bivesiculid trematodes collected from the intestine of Thalas soma lunare (Labridae) are shown to be morphologically consistent with adults of Bivesicula claviformis from Epinephelus fasciatus (Serranid ae). In addition, the immature bivesiculids have the same sequence for the second internal transcribed spacer of the ribosomal DNA. Comparis on with three other species of Bivesiculidae showed differences of bet ween 23% and 30%. These results show that bivesiculids may have three- host life-cycles in addition to the two-host life-cycles that have bee n demonstrated previously. The three-host life-cycle enables bivesicul ids to infect large carnivorous fishes. (C) 1998 Australian Society fo r Parasitology. Published by Elsevier Science Ltd. All rights reserved .