Specimens of Floriceps minacanthus Campbell & Beveridge, 1987 are reported from Carcharhinus melanopterus (Quoy & Gaimard, 1824) taken in the waters surrounding the island of Kirimati in the Republic of Kiribati in the Central Pacific Ocean. This represents a new host and a new locality record. The description of this species is expanded to include the presence of an ovary which is bilobed in cross section and a hermaphroditic duct. The surface features were examined by scanning electron microscopy. With the exception of the lateral margins of the bothridia and the apical region of the scolex, the scolex was found to be covered with palmate microtriches interspersed with filiform microtriches. The palmate microtriches varied in number of digitiform extensions depending on location. Elongate, bifid microtriches were present in the transition zone between the proximal and distal surfaces along the lateral margins of the bothridia. The apical region of the scolex was covered with filiform microtriches. The surface of the anterior margin of the strobila was covered with broad, flattened scale-like structures. The pattern of microthrix distribution was repeated for each of the bothridia of an individual, and this pattern was intraspecifically invariable. Comparison of our results with those from the seven other trypanorhynch species examined by previous authors with SEM indicates that there is much interspecific variability in both the morphology of microtriches present as well as their location on the scolex. This, coupled with the lack of intraspecific variability, confirms that these structures are systematically informative.

Five new species of Phoreiobothrium (Cestoda: Tetraphyllidea) are described from carcharhiniform sharks collected from a diversity of localities throughout the world. These are Phoreiobothrium perilocrocodilus n. sp. from Negaprion acutidens, Phoreiobothrium anticaporum n. sp. from Negaprion brevirostris, Phoreiobothrium lewinense n. sp. from Sphyrna lewini, Phoreiobothrium robertsoni n. sp. from Carcharhinus brachyurus, and Phoreiobothrium blissorum n. sp. from C. plumbeus, This brings the number of described species of Phoreiobothrium to 17. The new species from the lemon sharks, P. perilocrocodilus n. sp. and P. anticaporum n. sp., both possess more bothridial subloculi than do all species from hammerhead sharks, and fewer subloculi than do all species from sharks of Carcharhinus spp. Phoreiobothrium anticaporum n. sp. is unique among Phoreiobothrium species in that its genital pore is located in the extreme anterior portion of the proglottid. Phoreiobothrium lewinense n. sp. is unique in its possession of a combination of 8-11 subloculi and basal hook prongs that lack internal channels. Phoreiobothrium robertsoni n. sp. possesses 25-29 subloculi, triangular bothridia that flare posteriorly, and hooks that extend well beyond the middle of the bothridia. Phoreiobothrium blissorum n. sp. is most similar to Phoreiobothrium lasium in that it possesses rectangular bothridia with greater than 22 subloculi and long filitriches on its scolex. However, it differs from the latter species in that rather than articulating with one another, the bases of the medial and lateral hooks are widely separated; it also possesses 5-6 (vs.) 7-8 columns of testes. Phoreiobothrium lasium and Phoreiobothrium tiburonis are redescribed. The host associations of P. lasium are reevaluated and a neotype is designated for this species. The mature proglottid of P. tiburonis is described for the first time from voucher material collected from the type host and locality. These data suggest that the proglottid information provided in the original description, which was obtained from detached gravid proglottids, may have come from a tapeworm species other than P. tiburonis. All 7 species treated here in detail were examined with scanning electron microscopy; most were found to exhibit a microthrix pattern similar to that described previously for other members of the genus, e.g., Phoreiobothrium manirei. Bladelike spinitriches were present on the strobila, cephalic peduncle, and proximal bothridial surfaces, but were lacking from the distal bothridial surfaces. These spinitriches varied in length and density among species. Filitriches were present on all of these surfaces, but varied somewhat in length among species. Phoreiobothrium lewinense n. sp. is exceptional in that spinitriches were not seen on the proximal bothridial surfaces. A key to Phoreiobothrium species is provided. This work brings the number of carcharhinid shark species known to host this onchobothriid genus to 6, and the number of sphyrnid species to 5. Like many other onchobothr...