Bougainvillia Lesson 1830

Bougainvillia is a genus of hydroids in the family Bougainvilliidae in the class Hydrazoa. Members of the genus are characterised by having the marginal tentacles of their medusae arranged in four bundles. Some species are solitary and others are colonial but all are filter feeders. They are found in the Southern Ocean, having a circumpolar distribution, but some species also occur in the Northern Hemisphere, possibly travelling there as polyps on the hulls of ships.

Hydroid colony stolonal or branched, more rarely hydranths sessile; perisarc terminating at base of hydranth or extending onto hydranth as pseudohydrotheca; hydranth cylindrical to spindle-shaped, tentacles in one or two closely approximated whorls, tentacle-bases never enveloped by pseudohydrotheca, tentacles alternately inclined up- and downward (amphicoronate). Gonophores develop into free medusae, arising singly or in clusters from stem, branches or stolons. Medusa with four perradial marginal bulbs bearing two or more identical tentacles, with or without ocelli; four perradial oral tentacles, usually branched and ending in nematocyst clusters; gonads interradial or adradial on manubrium, sometimes also along basal perradial extensions of the manubrium.