Otobothrium cysticum (Cestoda : Trypanorhyncha) from the muscle of butterfishes (Stromateidae)

On the basis of the tentacular armature, surface ultrastructure, and morpho logical measurements of plerocerci obtained from the musculature of butterf ishes (Stromateidae), we corroborate an earlier proposal that Otobothrium c renacolle, a commonly reported trypanorhynch cestode from the northwestern Atlantic coast, is a junior synonym of O. cysticum. This action exemplifies at least an Atlantic Ocean and Indian Ocean distribution for O. cysticum. The infection in commercially important butterfishes shows that an otobothr iid trypanorhynch may heavily infect fish flesh and influence the market va lue of some fish species yet also be restricted to the body cavity of other fish intermediate hosts. Infections of O. cysticum in the flesh of Peprilu s burti (Gulf butterfish) and P. alepidotus (harvestfish) in the Gulf of Me xico has varied annually since 1970, with samples ranging in prevalence bet ween 20% and 100% and in mean intensity between 1 and 3,500 or more pleroce rci per fish. Comparative infections in P. burti from the Gulf of Mexico an d P, triacanthus (butterfish) from the Atlantic Ocean demonstrate a present geographic difference in infections. The prevalence and mean intensity in 4 collections of butterfishes ranged from 9% to 98% of the fish and from 1 to 678 plerocerci in a subsample of tissue, respectively, with prevalent an d heavy infections being observed in the Gulf of Mexico fish and relatively few individuals being infected with few worms in the Atlantic fish. A slig ht host response in the butterfishes involving some fatty infiltration and inflammatory infiltration was associated with the metacestode. In some larg er fish, encapsulations were yellow, and in a few cases, worms had degenera ted. This finding and an increase in intensity with fish weight suggest a c ontinual accumulation of the worms in association with little host resistan ce.