Two new species of Pileolaria (Polychaeta: Spirorbidae) from the Southern Hemisphere with a brief review of related species

Abstract

Two new polychaete species of family Spirorbidae are described, both similar to those species of Pileolaria that have the distal part of the brood-chamber smooth and domed or bilobed. Pileolaria connexa sp.n. from Kerguelen Island (and probably Palmer Archipelago), unlike most species of the genus, commonly retains the primary operculum (plate and talon) distal to the brood chamber, and has sickle chaetae with unusually long distal serrated parts of the blades. Pileolaria invultuosa sp.n. from Bouvet Island and Adelie Land (and perhaps Enderby Land and Signy Island) sheds the primary operculum before the brood chamber is fully developed and has distal serrated parts of sickle chaetae blades similar in length to proximal thick parts of the blades. Both new species are similar, but unusual amongst this group, in having a shallow calcified cap restricted to the distal part of the brood chamber. The primary opercula of both species differ from each other (and from those of most Pileolaria species) in the shape and position of the distal plates talons.