On four monostiliferous hoplonemerteans, including three new genera and species from Washington state and British Columbia

Abstract

Frontonemertes serpentina, Satellitenemertes satellitensis and Sanjuannemertes willowsi new genera and species are described as three members of the order Hoplonemertea, suborder Monostilifera. In general morphology, F. serpentina is most similar to Nemertes rubrolineata in having the two layers of the body wall longitudinal musculature, no pre‐cerebral septum and retractor muscles originating in the outer longitudinal muscle layer in the cephalic region {Chernyshev (1992) proposed a new genus, Tetranemertes, for Nemertes [type species, N. antonina Quatrefages, 1846]}. Satellitenemertes satellitensis appears to be most closely related to members of the genus Amphiporus. Sanjuannemertes willowsi has a common atrium for the proboscis pore and mouth, as in some polystiliferous hoplonemerteans. The original description of Nipponnemertes bimaculata (Coe 1901) is supplemented on the basis of re‐observation of its features. The significant characters are explained and discussed.