Eudendrium ritchei
Colonies growing luxuriantly on algal holdfast.
Stems up to 1 cm in height and 0.13-0.18mm in width, unfascicled, irregularly branched, arising from a smooth reticulating hydrorhiza. Stems completely and closely annulated throughout, perisarc very thick.
Hydranths terminal on branches, with 20- 24 tentacles.
Male and female gonophores borne on different but closely associated colonies on algal substrate. Immature male gonophore with an apical tubercule, mature gonophore 1-2 chambered, distal 5 chamber 0.14-0.2mm in diameter, borne on lower stems of colony in a tight cluster of20-30 on a blastostyle devoid of tentacles at all stages. Young female gonophore with a strongly bifurcated spadix; gonophores borne in clusters of 4-6 in various stages of development below a hydranth with a reduced number of tentacles. At maturity, the tentacles are completely absent, with 2-5 mature gonophores scattered along the blastostyle. Length of mature female gonophore 0.3mm, width 0.25mm.
Nematocysts of two kinds present:
(i) Microbasic euryteles, capsule 6-7 x 2.5 µm, shaft 5 µm long, abundant in tentacles.
(ii) Larger microbasic euryteles, capsule bean-shaped, 16.5-18 x 7-8 µm, shaft thick, at least 37 µm long, spinous, the thread very long and covered with bristles. Abundant on hydranth, spadix of female, and on apical tubercule of male gonophore.
Colour: Hydranths and gonophores cream coloured, perisarc dark shining brown.
South Africa and New Zealand.
Subtidal, epiphytic on algae.