CYCLIOPHORA IS A NEW PHYLUM WITH AFFINITIES TO ENTOPROCTA AND ECTOPROCTA

THE mouthparts of the Norway lobster Nephrops are colonized by an acoe lomate metazoan, Symbion pandora gen. et sp, nov. Sessile stages conti nually produce inner buds replacing feeding structures, They also prod uce one of three motile stages: (1) larvae containing new feeding stag es, (2) dwarf males, which settle on feeding stages, or (3) females, w hich settle onto lobster mouthparts, and eventually degenerate, giving rise to dispersive larvae, All motile stages are short-lived, and do not feed, The structure and function of the cilia suggest a phylogenet ic position in Protostomia, while some aspects of inner budding and br ooding of larvae are similar to those of Entoprocta and Ectoprocta. Th e dispersive larva possesses a mesodermal supporting chordoid structur e, otherwise absent in protostomian larvae, We believe that ail the ab ove features of this previously undescribed species warrant the recogn ition of a new phylum with affinities to Ectoprocta and Entoprocta.