Living genera of sea pens (Goelenterata: Octocorallia: Pennatulacea): illustrated key and synopses

An illustrated dichotomous key and synopses of the 32 genera of living pennatulacean octocorals are presented, which incorporate new morphological and distributional data from the examination of recendy collected material. In addition, a key to the 15 extant families, lists of valid genera, synonyms, and a table of comparative characters are also included. Lasdy, a revised classification and phylogenetic considerations are presented. Preliminary investigations indicate that the traditional higher classification scheme of the Pennatulacea is inadequate for reasons of paraphyly and intermediate taxa, that tend to negate precise distinctions between some of the nominal higher taxa. Of the approximately 436 described species of sea pens worldwide, only 186 (or 43%) are estimated to be valid. In addition, several undescribed species have recently been discovered, and others will no doubt be discovered in the future. It is therefore estimated that the extant pennatulacean fauna of the world comprises approximately 200 species in 32 genera.