Description of redia and cercaria of Paragonimus peruvianus from experimentally infected Aroapyrgus colombiensis of Condebamba Valley, Peru

Although no natural infections with lung flukes were encountered in the hydrobioid snail Aroapyrgus colombiensis from streams in the Condebamba Valley, Peru, laboratory-bred snails were readily susceptible to infection with miracidia of Paragonimus peruvianus. The redia and cercaria are described for the first time for those of neotropical lung flukes. Cercariae inside rediae did not have a stylet and development was apparently completed outside the rediae in snail tissues. The microcercous xiphidiocercaria had 2 groups of gland cells on each side; the outer consisted of 5 cells and the inner of 3 cells, all with ducts opening at the stylet. The excretory bladder was large, often triangular, was thick-walled, and of 1 layer of cuboidal cells. The redia lacked procrusculi and had a short intestine which was slightly longer than the pharynx.