A new octocoral genus (Cnidaria : Anthozoa) from Antarctic waters

Sphaeralcyon weddellensis gen. nov. et sp. nov. is described and illustrate d from three colonies collected in the eastern Weddell Sea on the Polarster n cruises ANT V/3 and ANT VI/3. The new genus is compared with three closel y related alcyoniid genera, all having capitate or mushroom-shaped colonies and dimorphic polyps. Sphaeralcyon is readily distinguishable from Malacac anthus by the presence of sclerites (absent in the latter genus), and from Anthomastus by sclerite shape, mainly in the form of tuberculate spheroids, and by the horny periderm on the stalk (absent in Anthomastus). Sphaeralcy on also differs from Verseveldtia in the set of sclerites, which are elonga te spiny rods and a different type of tuberculate spheroid, and in the pres ence of eight-points as anthocodial armature (absent in Verseveldtia). The discovery of this new genus lends further support to the notion that divers ity in benthic communities in Antarctica is higher than suggested by previo us studies.