Stephanoscyphus planulophorus n. spec., ein neuer Scyphopolyp mit einem neuen Entwicklungsmodus

A new solitary species ofStephanoscyphus (order Coronatae) is described. It has been collected in submarine caves of the rocky shore near Marseille, Mediterranean Sea, where it lives attached to colonies of corals at a depth of 10 to 20 m. The essential characteristics of the peridermal tube and the soft body are outlined. They are not sufficient to distinguish significantly the new species from others of the same genus. Identification was possible by the observation of a unique way of development which is characterized by the complete reduction of the free swimming medusa generation. First, the strobilation phase undergoes normal development whereby a chain of numerous ephyra-like stages is originated in the tube of the polyp. Simultaneously, its head is transformed into an opercular apparatus in the normal way whereby the aperture of the tube is closed completely. The strobilation stages must be considered as true young ephyrae because of their flat shape, the regularly formed marginal lappets and contraction movements. Contrary to the normal development, the ephyrae metamorphozise directly to ciliated free swimming planulae. After a long period of incubation, the planulae hatch from the tube and begin a planctonic way of life for a period of about 14 to 50 days. They attach then to the substratum in the normal way and develop into young polyps with a basic disk and small peridermal tube. Thus, the life cycle is completed. Because of the existence of a strobilation phase and the production of ephyrae the mode of development must be considered as a reduced metagenesis. The problem of the existence and special realization of the sexual phase remains unsolved. The diagnosis of the new species is given, and the systematical, evolutionary and ecological aspects of the new mode of development are discussed.