Molecular Identification of Larvae of a Tetraphyllidean Tapeworm (Platyhelminthes: Eucestoda) in a Razor Clam as an Alternative Intermediate Host in the Life Cycle of Acanthobothrium brevissime

Dwarf razor clams (Ensis minor) in the Gulf of Mexico lire known to be infected with plerocercoid larvae of it tetraphyllidean tapeworm. Here, we show that these larvae live unencysted in the intestinal lumen of the clam. Morphologically, the larvae lire similar to (although significantly larger than) tapeworm larvae previously described living in the gut of amphioxus (Branchiostoma floridae) from the same habitat. Sequence data from the D2 region of the 28S rDNA from clam-infecting larvae were identical to the sequence of Acanthobothrium brevissime isolated as larvae from amphioxus and its adults from a stingray (Dasyatis say). The sequence data leave little doubt that the dwarf razor clam and the amphioxus are alternative intermediate hosts in the life cycle of A. brevissime.