Scanning electron microscopy of the scolex and neck of the tapeworm Cathetocephalus thatcheri [Cestoda, Tetraphyllidea] from the sandbar shark Carcharhinus plumbeus [Chondrichthyes, Elasmobranchii]

Scanning electron microscopy of the scolex and neck of the cestode Cathetocephalus thatcheri confirmed earlier light-microscope descriptions showing that the scolex consists of a single apical lenticular adhesive complex, oriented transverse to the long axis of the strobila. The apical region of the scolex consists of a medial ridge from which extend numerous pairs of short bilamellate septa. On each side of the medial ridge, along its entire length, is a ridge in the form of sinusoidal wave that forms a loop around each of the septa. The tegument of the anterior surface of the medial ridge is formed into numerous tegumental folds that are aligned perpendicular to the long axis of the ridge. Posteriorly, the scolex has a rugose surface and forms a collar or lip around the upper part of the adherent surface. The sinusoidal ridges are continuous around the ends of the scolex. At the ends, the medial ridge tapers considerably. The tegument of the neck bears numerous papillae. No microtriches were observed on any part of the scolex or neck.