FUNCTIONAL-MORPHOLOGY OF THE FOREGUT OF CHONOPELTIS-AUSTRALIS BOXSHALL (BRANCHIURA)

The morphology of the foregut of the ectoparastic branchiuran Chonopel tis australis is described from serial transverse, longitudinal, and f rontal sections of whole parasites and from SEM micrographs. The foreg ut is differentiated into four histomorphological regions: a preoral c avity, housed inside the proboscis and containing the tongue and mandi bles; an ascending esophagus supplied with constrictor, longitudinal, and dilator muscles; a horizontal esophagus supplied with constrictor muscles only; and an esophageal funnel, containing cuticle-lined inner and recurrent walls, reminiscent of the cardia of muscoid flies. The mandibles apparently do not function as lacerating organs, but instead cram mucus and cellular detritus into the preoral cavity. Five dentig erous plates, guarding the oral aperture, function as a filter during feeding. The muscle complex in the walls of the ascending esophagus fa cilitates movement of aliment through the foregut into the anterior mi dgut. The comparative morphology and functional significance of each p art of the foregut are discussed.