Praesomal musculature of the acanthocephalan genus Mediorhynchus Van Cleave 1916.

The praesomal musculature of Mediorhynchus is described. The proboscis is considered to consist of 3 zones: an anterior protoboscis, a median mesoboscis, and a posterior teloboscis. New structures reported are mesoboscis retractor muscles, the formation of 3 ligament strands from the proboscis retractor muscles, a teloboscis inflator muscle, and conduit through the protrusor muscle sheath. Some aspects of the taxonomy of Mediorhynchus are discussed.