Mycomyzostoma calcidicola gen. et sp. nov., the First Extant Parasitic Myzostome Infesting Crinoid Stalks, with a Nomenclatural Appendix by M. J. Grygier

Abstract

A new genus and species of Myzostomida is described by means of light and electron microscopy. Mycomyzostoma calcidicola is a parasitic myzostome inducing cysts on the stalks of Saracrinus nobilis, a crinoid collected around New Caledonia. The main characteristics of the species are the unusual body shape of the female, the total regression of the female parapodia, the absence of digestive caeca in the females, the total regression of the digestive system in the males, and the site of the cysts. The discovery of M. calcidicola re-opens the debate about the probable myzostomidan origin of parasitic traces occurring on pre-Pennsylvanian crinoid stalks.