Relationship between Dictyocotyle and Calicotyle

Abstract

RECENTLY, the opinion has been expressed that the endoparasitic monogenetic trematode Dictyocotyle coeliaca is simply a cœlomic form of the common cloacal parasite Calicotyle which has entered, through the abdominal pores, the body cavity of certain species of Raia ¹. The normal posterior adhesive organ (‘opisthaptor’) was thought to be lost, and its central boss to regenerate a ‘pseudohaptor’. The evidence given in support of this supposed ontogenetic migration was: (1) the finding, in an abdominal canal, of a trematode which had lost its opisthaptor; (2) the recovery, from the cloaca, of six isolated opisthaptors each with a central perforation which matched the boss of the mutilated specimen.