Systematics of the candelabrum gorgonian corals (Eunicea Lamouroux; Plexauridae; Octocorallia; Cnidaria)

Candelabrum gorgonian corals (genus Eunicea Lamouroux, 1816), with 15 valid species, comprise the most diverse and abundant group of octocorals in Caribbean coral reefs. The systematics of Eunicea was estimated based on 17 discrete morphological characters, mostly from sclerite morphology. Club sclerites, found on the surface of gorgonian tissue, provided the largest number of informative characters. A maximum parsimony analysis corroborated the monophyletic status of the group and the two internal groups (subgenera Eunicea s.s. and Euniceopsis Verrill). Differentiation based on the distribution and architecture of modules (e.g. polyps and calyces), as well as colony size and fecundity in females, was consistent amongst sister species (e.g. the new species and their closest morphological sister species) but not within species [e.g. amongst Eunicea succinea (Pallas) morphotypes], suggesting species boundaries for this group. Candelabrum gorgonian corals seem to be distributed indistinctively throughout the Caribbean province, where habitat requirements are met. One new species widely distributed in the Caribbean was described (Eunicea tayrona sp. nov.) using electron microscopy. Eunicea tayrona is externally similar to Eunicea fusca but there are numerous morphological and ecological differences between them. The morphotypes and phenotypic plasticity from Eunicea clavigera Bayer, Eunicea calyculata (Ellis & Solander), and Eunicea tourneforti Milne Edwards & Haime still deserve further study and might clarify the presence of additional new Eunicea species. (C) 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 157, 237-263.