Cathetocephalus thatcheri gen. et sp. n. (Tetraphyllidea: Cathetocephalidae fam. n.) from the Bull Shark: A Species Demonstrating Multistrobilization

Abstract

Cathetocephalus thatcheri gen. et sp. n. is described from the spiral valve of the bull shark, Carcharhinus leucas (Valenciennes), taken in the Gulf of Mexico and the Atlantic coast of Florida. A new family is erected for the new genus. The species most closely resembles Pillersium owenium Southwell, 1927, in that both possess a scolex which is perpendicular to the long axis of the strobila. It differs, however, in having a single neck and holdfast organ rather than a bifurcate neck with 2 bothridia. Also, the surfaces of the scolex differ from those of P. owenium by possessing fleshy pa- pilliform structures on the leading and trailing edges rather than leaflike folds. Specimens with sev- eral strobilae are figured and discussed. A heavy infection of cestodes was found in the spiral valve of two specimens of the bull shark, Carcharhinus leucas (Valenciennes), that had been collected in Galveston Bay, Texas. The sharks had been flown to Sea World, San Diego, California, and died several days later. Additional specimens were also recovered from the same species of host at Mi- ami, Florida. The presence in those worms of a unique multistrobilate condition in some specimens prompted this study. The species does not have the typical tetraphyllidean scolex, but is considered here as representing a new genus in a new family in the order Tetraphyllidea. Worms were fixed in AFA, Bouin's fluid, or 10% formalin. Whole mounts were stained with cellestine blue B or Semichon's carmine. Sections of other specimens were cut at 6, 8, and 10 Au and stained with hematoxylin-eosin or Mallory's trichrome stain. All material was dehydrated in ethanol, cleared in xylene, and mounted in Piccolyte. Drawings were made with the aid of a drawing tube and stereo- scopic microscope. Average measurements are given, with ranges in parentheses. They are in millimeters unless otherwise indicated.