LIFE HISTORY TRAITS OF A NEW SPECIES OF POLYCHAETE PROCERAEA SP.N. (POLYCHAETA, SYLLIDAE) WITH LARVAE PARASITIZING THE HYDROID ABIETINARIA TURGIDA (HYDROZOA, SERTULLARIIDAE)
Britayev, T. A.1 & San-Martin, G. 2
1A.N.Severtzov Institute of Ecology and Evolution, Russian Academy of Sciences, Leninsky Prosp. 33, Moscow 117071, Russia
2 Departamento de Biologia, Unidad de Zoologia, Facultad de Ciencias, Universidad Autonoma de Madrid, 28049, Madrid, Espana
Numerous small worms of a new polychaete species, Proceraea n. sp., at different stages of development were found inside the hydrothecae and mucous tubes attached to the colonial hydroid Abietinaria turgida (Clark, 1876) on the coast of Medny Isl. (Commander Isl.), 5-12 m depth, in August 1986. The worm larvae live inside hydrothecae at the base of polyps. The smallest larvae are yolk-filled, lack setae, and have a single pair of eyes and a tuft of short cilia in the apical part of prostomium. As larvae grow, the yolk and the tuft of cilia disappear. Larger specimens possess setae and dorsal cirri on several anterior parapodia, then the pharynx appears and juveniles start feeding upon the host. Finally, the worm occupies the entire cavity of the hydrothecae, and a conspicuous additional cylindrical part of hydrothecae appears distally as a result of infestation. Upon reaching 10-11 setigers, the juveniles leave the hydrothecae and build mucous tubes attached to the stem or branches of the hydroid colony and continue their growth up to the adult. The proventriculus and the teeth of the trepan are formed when the worms leave the hydrothecae. In contrast to Autolytus spp., all stages lack ciliary bands on the body. The female stolon (Sacconereis) was examined. Proceraea n. sp.differs from closely related species P. okadai and P. mukaishimus by the structure of trepan, the length of head appendages and nuchal epaulettes.