Family RHIZOSTOMATIDAE Eschscholtz, 1829

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Family RHIZOSTOMATIDAE Eschscholtz, 1829

Compiler and date details

June 2012 - Lisa-ann Gershwin

DRAFT RECORD

This taxon is under review. This record is released now for public view, prior to final verification. For further information or comment email us.

Introduction

The family Rhizostomatidae contains the genera Eupilema Haeckel, 1880, Rhizostoma Cuvier, 1800 and Rhopilema Haeckel, 1880. Of these, only Rhopilema has been reported in Australian waters, and only very rarely.

The group is easily identified by having scapulets on the upper portions of the oral arms, which are coalesced in the proximal portion only; the distal portion of the oral arms are three-winged, and they usually have a terminal club. Eupilema is characterised by lacking filaments, clubs or other appendages on the oral arms. Rhizostoma is characterised by having small scapulets and a short manubrium, a single club-like terminal appendage, no clubs or filaments, and typically with a ring canal. Rhopilema is characterised by having large scapulets and a long manubrium, a large terminal club, numerous clubs or filaments, and typically lacking a ring canal.

Stiasny (1921: 168) studied specimens from Japan and concluded that the species is probably a damaged form of Rhopilema escuelnta; however, it is possible that he did not have the right species to begin with: Eupilema scapulare is from the Sunda Archipelago and Sumatra, whereas R. esculenta is from Japan. The validity of the genus Eupilema was questioned by Kramp (1970: 15), who believed it to be obsolete based on Stiasny's conclusions. However, the genus was considered valid by Pagès and his colleagues (1992), who added a new species to Haeckel's genus.

Diagnosis

Scapulatae with mouth-arms coalesced in proximal portion only; without a primary mouth opening; rnanubrium with a complicated canal system; distal portion of arms three-winged, usually with a terminal club.