Two species of Edwardsia having gigantic nematocysts, E. aff. tuberculata br />and E. alternobomen sp. nov. (Cnidaria; Anthozoa; Actiniaria; Edwardsiidae) from Japan.

The genus Edwardsia de Quatrefages, 1842 is the group of worm-like sea anemones of the family Edwardsiidae, characterized by having nemathybomes on their body wall and physa at their aboral end. This genus accommodates a lot of species, but only three have been known from Japanese waters. In this study, we report Edwardsia aff. tuberculata Duben and Koren, 1847 and describe a new species E. alternobomen sp. nov. from seas around Japan. Both are characterized by prominent, papillae-like nemathybomes which contain unusually large nematocysts. Some nematocysts of E. alternobomen sp. nov. are over 200 µm in length, which are the largest reported for a member of Edwardsiidae.