Redescription of Rhodopsis pusih Bush, a little known but widely distributed species of Serpullidae (Polychaeta)

Rhodopsis pusilla Bush 1905. a minute species characterized by a chitinous opereular plate bearing numerous spines is redescribed and a neotype is designated. Apomatolos Uchida. 1978 is synonymized with Rhodopsis. Ventral fillform mouth‐palps are present a rarely observed character in common with Pseudovermilia Bush. Variability between and within populations from different seas is discussed. Rhodopsis pusilla from Heron Island shows opercular dimorphism. Pouch‐like brood chambers similar in texture (SEM) to the Rhodopsis tubes and integrally associated with rings marking successive position of the peristome were found on some tubes. These brood chambers. presumed to belong to Rhodopsis are described with conjectures as to their mode of formation. Some aspects of opercular polymorphism in serpulids are discussed.