ULTRASTRUCTURE AND SYSTEMATIC SIGNIFICANCE OF THE EPIDERMIS AND HAEMOCOEL OF RHODOPE (GASTROPODA, NUDIBRANCHIA, DORIDOIDEA)

The fine structure of the epidermis and haemocoel of Rhodope veranii K olliker, 1847 and Rhodope transtrosa Salvini-Plawen, 1991 has been inv estigated by means of transmission electron microscopy in order to spe cify the systematic position of this highly enigmatic genus and family among the opisthobranch gastropods. Phaosome photoreceptors in the ep idermis and rhogocytes (pore cells) in the haemocoel confirm the mollu scan nature of Rhodope; also spiral sperm indicates once more its euth yneuran position. Most significant is the presence of a specific vesic le system throughout the haemocoel, which is formed by cells strongly resembling doridoid blood gland cells. We therefore regard Rhodope as a highly aberrant and modified member of the Doridoidea, although a po sition in the Notaspidea cannot be fully excluded.