Cysticolous Myzostomida, Notopharyngoides platypus from Comanthina nobilis (Echinodermata : Crinoidea), at Kushimoto, Honshu, Japan

Abstract

About 20% of individuals of the comatulid crinoid Comanthina nobilis (Carpenter, 1884) at Shionomisaki, the southernmost point of the island of Honshu, Japan, are infested by the cysticolous myzostomidan worm originally described as Myzostoma platypus Graff, 1887. Up to four cysts per host occur. This parasite had been collected previously only in the Philippines by the 'Challenger' Expedition, from the same host species. The present specimens differ in having a few to many supernumerary marginal cirri and up to six (versus three to five) separate tabular outgrowths in a row along the ventral midline. It is proposed to reassign this species as the most plesiomorphic member of the genus Notopharyngoides Uchida, 1992.