Stephanoscyphus (Scyphozoa, Coronatae) und seine direkte Abstammung von den fossilen Conulata

Abstract

The scyphopolyp StephanoscyphusAllman 1874 represents the polyp generation of the scyphomedusan order Coronatae. Though this polyp has been known for more than a hundred years its general morphology, systematics, and evolution have been inadequately described. Participating in the International Indian Ocean Expedition, 1964 to 1965, on board of the German research vessel "Meteor", the author was able to collect a sufficient supply of living Stephanoscyphus off the coasts of South Arabia and East Africa. For the first time, it was possible to rear these polyps in laboratory cultures. A thorough investigation of morphology, developmental history and behaviour based on longterm observations of the living polyps gave clear indications that Stephanoscyphus directly descended from the fossil group of Conulata, the scyphozoan nature of which has been affirmed by Kiderlen (1937) and Knight (1937). The main feature which Stephanoscyphus has in common with the Conulata is the possession of a periderm tube. The characteristics found in a detailed investigation of the periderm tube conform well with those found in the periderm of the Conulata except for the closure of the aperture by triangular flaps which are absent in Stephanoscyphus. The soft body contains primitive features as well. Hence it must be concluded finally that the type of organization which the fossil ancestors exhibited has survived in Stephanoscyphus and that the Coronatae represent the most basic group of all living Scyphozoa. On the other hand, the results give strong support for the scyphozoan nature of the Conulata, the organization and life history of which have been elucidated by the observations of the living representatives of Stephanoscyphus. © 1966 Biologischen Anstalt Helgoland.