A new species of phyllodocid polychaete, Mysta ctena n. sp., is described from Misaki, central Honshu, Japan. It is distinguished from other Mysta in having two types of thorny proboscis papillae, rather than a single kind. Two previously unobserved characters in Mysta are introduced: a row of papillae on the dorsal tentacular cirri, and small conical papillae on the inside of the proboscis. A table is provided with diagnostic characters for all species of Mysta.
Annelida, Polychaeta, Phyllodocidae, Mysta ctena n. sp., Japan, new species.