Morphological investigations into Floriceps minacanthus (Trypanorhyncha: Lacistorhynchidae) with analysis of the systematic utility of scolex microtriches.
Specimens of Floriceps minacanthus are reported from Carcharhinus melanopterus, taken in the water 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 (SEM). 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 these results with those from the 7 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.