Revision of the Genera Bellonella, Eleutherobia, Nidalia and Nidaliopsis (Octocorallia: Alcyoniidae and Nidalliidae), with descriptions of two new Genera

Nineteen species of Alcyoniidae formerly assigned to various genera are here placed in the genera Bellonella and Eleutherobia; three new species are described in Bellonella. Sixteen species characterized by an abundance of capstans among their sclerites, formerly assigned to Alcyonium, Bellonella and Nidalia are now transferred as valid species or synonyms to the genus Eleutherobia, in which two new species are described making a total of 14 valid species. A new genus Inflatocalyx is established for a digitiform subantarctic species having only very few sclerites, in the form of nearly smooth spindles, and polyps retractile within large, inflated calyces. Six species comprising the genus Cactogorgia are transferred to Nidalia, and three new species are described, bringing the total known for the genus to twelve. The species described by Tixier-Durivault as Alcyonium altum and A. violaceum are shown to be dimorphic and are transferred to Nidaliopsis. J. S. Thomson's Sinularia unilobata is redescribed and made the type of a new genus Pieterfaurea. The sclerites of most species are illustrated for the first time by scanning electron micrographs. Keys to the genera of Alcyoniidae and Nidalliidae and to the species of Bellonella, Eleutherobia and Nidalia are presented.