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r: Phoreiobothrium manirei n. sp. is described from the spiral intestines of 3 immature individuals of the great hammerhead shark Sphyrna mokarran collected off of the west coast of Florida. This cestode is unusual in that it possesses 4 muscular papillae on the anterior margin of the accessory sucker. Numerous small protrusions with central cilium-like projections were conspicuous throughout the posterior margin of each bothridium. This species possesses the unique combination of bothridia posteriorly subdivided into subloculi and hooks with extended bases and 2 rather than 3 prongs. In fact, the hooks are strikingly like those of species in the genera Dicranobothrium and Platybothrium. This combination of characters suggests that the bifid hook condition is plesiomorphic with respect to the trifid hook condition within the Onchobothriidae. These data further suggest that the triloculated bothridial condition is plesiomorphic relative to the biloculated condition. Dissection of the spiral intestines of 3 immature individuals of the great hammerhead shark Sphyrna mokarran (Riippell, 1837), collected from the west coast of Florida in 1994 by re- searchers at the Mote Marine Laboratory, led to the discovery of multiple specimens of a cestode, which, based on bothridial and segment morphological features, we describe here as a new species of Phoreiobothrium Linton, 1889. Despite its otherwise Phoreiobothrium-like scolex and segment morphology, this spe- cies bears hooks that are unusual in their remarkable resem- blance to the hooks of species normally assigned to Dicrano- bothrium Euzet, 1953 or Platybothrium Linton, 1890. The dis- covery of this combination of characters in a single taxon has important implications for the interpretation of the evolution of scolex features in the Onchobothriidae. |
