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

On the basis of the tentacular armature, surface ultrastructure, and morphological measurements of plerocerci obtained from the musculature of butterfishes (Stromateidae), we corroborate an earlier proposal that Otobothrium crenacolle, 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 otobothriid trypanorhynch may heavily infect fish flesh and influence the market value 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 Peprilus burti (Gulf butterfish) and P. alepidotus (harvestfish) in the Gulf of Mexico has varied annually since 1970, with samples ranging in prevalence between 20% and 100% and in mean intensity between 1 and 3,500 or more plerocerci per fish. Comparative infections in P. burti from the Gulf of Mexico and 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 and heavy infections being observed in the Gulf of Mexico fish and relatively few individuals being infected with few worms in the Atlantic fish. A slight host response in the butterfishes involving some fatty infiltration and inflammatory infiltration was associated with the metacestode. In some larger fish, encapsulations were yellow, and in a few cases, worms had degenerated. This finding and an increase in intensity with fish weight suggest a continual accumulation of the worms in association with little host resistance.