Abstract
This is the third of three volumes of Keys to the Trematoda, a series on the systematics and identification of the Class Trematoda of the Phylum Platyhelminthes. This volume includes five plagiorchiidan superfamilies, i.e., the Opisthorchioidea, Gorgoderoidea, Monorchioidea, Plagiorchioidea and Microphalloidea plus the strigeidan family Didymozoidae. To facilitate orderly discussion, the descriptions of the included families and genera are organized under each superfamily, which is considered as the basic unit of classification. In the first chapter, a cumulative key is provided to the superfamilies. Each superfamily and family group is generally treated as a separate chapter. Each chapter has an introduction outlining the history of the group and recent or current changes within it, followed by keys and diagnoses for suprageneric groups and genera. At least one illustration for a representative of each genus considered valid is included. In addition, this book provides an index to taxa and a bibliography covering all the chapters in the volume.