Bougainvillia muscus (Allman, 1863)

Colonies bushy, reaching a height of 5 cm.

Stems erect, sometimes weakly fascicled, branching profuse and irregular, branches forming an acute angle with the stem. Perisarc wrinkled or corrugated at the origin of branches and hydranth pedicels but otherwise smooth. Perisarc of stem continues over the lower part of the hydranth as a shallow cup-shaped dish (pseudohydrotheca);

Hydranth with a bunch of 9 - 15 long, filiform tentacles protruding from the pseudohydrotheca.

Medusa buds pear-shaped, arising from the hydranth pedicels and smaller branches. Medusa at liberation elongate globular, about 0.4 mm in diameter, stomach short, spherical, mouth with 4 capitate tentacles terminating in nematocyst clusters. Margin of bell with 4 large marginal bulbs, one at the base of each radial canal, each with two tentacles and two ocelli. Jelly of adult medusa thick, each marginal bulb now with 4 - 9 tentacles, oral tentacles dichotomously branched and gonads surrounding the stomach.

Colour: Colony white, body of hydranth orange, tentacles white. Colour of the living medusa in local waters unknown.