ABSTRACT
The systematics of the Cestoda has been disputed in recent decades. In particular, the position of the monozoic taxa (Gyrocotylidea, Amphilinidea and Caryophyllidea) has been controversial (e.g., Arme and Pappas 1983). During recent years, however, after comprehensive ultrastructural and genetic investigations, a consensus phylogenetic system has been established for the cestodes. The Cestoda arc monophyletic, characterized by at least eight autapomorphies. The Cestoda comprises the Gyrocotylidea, the Amphilinidea and the Cestoidea sensu Ehlers (1984, 1985a). The Gyrocotylidea is the sister-group of the other two taxa, which together form the Nephroposticophora Ehlers 1984. The Gyrocotylidea – including the genus Gyrocotyloides – are considered monophyletic. Within the Nephroposticophora, the Amphilinidea which are well-characterized by a number of autapomorphies and the Cestoidea (synonymous to the so-called Eucestoda of Hoberg et al. 1999b: all other Cestoda characterized by a six-hooked primary larva) are sister-groups. The Cestoidea (in this chapter this suffix will be used according to the arguments for a differentiation between Cestoidea, Eucestoda and Caryophyllidea given by Ehlers 1985a) share at least six autapomorphies.
