Structural description of three myzostomes parasites of crinoids and of the skeletal deformations they induce on their hosts

Three species of deforming myzostomes infested the crinoids collected during the French Expeditions of the last decade in the Pacific. Cystimyzostomum tenuispinum is the most abundant and infests five different species of crinoids. It induces galls on the arms or pinnules of its hosts. The two other myzostome species are rarer. Cystimyzostomum murrayi induces a bean shaped cyst attached at the base of the arms of an undetermined species of comatulid crinoid. Cystimyzostomum deformator was previously reported to induce galls on the host’s pinnules. Here, we report that it can also induce a half ball shaped cyst on the oral side of the arms of Saracrinus angulatus.