Eudendrium balei Watson, 1985

Colonies up to 10 cm in height.

Hydrorhiza a tangled mass of tubes, becoming erect at intervals as stems.

Stems more or less straight, perisarc thick, smooth, shining, fascicled to about halfway up colony, primary branches long, of same diameter as stem, given off irregularly or in an irregular whorl in three planes at an acute angle to stem. Rebranching common, repeated up to 5 times, each branch commencing with up to 7 distinct annulations, minor branches and hydranth pedicels often indistinctly corrugated throughout their length.

Hydranth pedicels long, perisarc usually terminating sharply well below hydranth, but sometimes grading into hydranth. Hydranths large, with 20-24 tentacles surrounded by a wide hypostome; usually a contraction groove near base.

Sexes on separate colonies, male and female gonophores borne on all parts of colony except the most distal branches. Male gonophore 3-chambered, in clusters of up to 12 on a wrinkled pedicel below a fully formed hydranth, immature gonophore with a tiny apical tubercule, lost at maturity, distal chamber of mature gonophore bun-shaped with inflated spadix. Female gonophores borne below a fully-developed hydranth with a hypostome and a reduced number of tentacles (see remarks), up to 20 gonophores in various stages of maturity scattered along a wrinkled blastostyle. Immature gonophores large, spadix unbranched, with scattered clusters of nematocysts. Mature gonophore egg-shaped, on a short pedicel, containing a single egg enclosed in a very thin transparent pellicle.

Nematocysts of two kinds present:

— Microbasic euryteles, capsule 8-10 x 4-5 µm, shaft 7 µm long, with several large spines. Very abundant in tentacles.

— Microbasic mastigophores, capsule bean-shaped, 19-22 x 10 µm long, 1.5 µm thick, thread 400 µm long, thick and spinous. Moderately common on hypostome, sometimes on body of hydranth and in clusters on spadix of immature female gonophore.

Colour: Perisarc of older stems shining dark brown, lighter in younger parts of colony. Body of hydranth orange, tentacles pink, male gonophores pearly pink, spadix deep orange; female gonophores brilliant orange. Overall colour of colony, orange to pink.