Coryne eximia Allman, 1859

Hydroid:

Hydrorhiza cylindrical, 0.15- 0.25 mm in width, creeping on surface of hard substrate, or embedded in the surface of sponge or compound ascidians. Perisarc of hydrorhiza may be thin or quite thick, depending on age of colony.

Stems reaching 5 mm in height, 0.12-0.15 mm in width, perisarc variable in thickness, usually thicker proximally, becoming thinner distally, either entirely ridged throughout, annulated, or occasionally, smooth. Stems may be simple, or with one or two short branches, hydranths terminal.

Hydranths spindle shaped in extension, 0.8-1 mm in length, with 12- 16 capitate tentacles in 4 or 5 irregular verticils, including 4-5 tentacles around the hypostome. Fertile hydranths contracted, with up to 6 medusa buds in various stages of development.

Colour: Body of hydranth orange-pink, tentacles translucent white.

Nematocysts of two types present in hydroid:

— Stenoteles, moderately abundant, capsule oval, butt about two thirds length of capsule with 3 long barbs. Length of capsule 7.5µm, width 5 µm.

— Microbasic euryteles, very abundant, capsule oval, length 4 µm, width 2 µm, butt about same length as capsule.

Medusa:

Newly liberated medusa deep bell shaped, symmetrical, umbrella deeper than wide, 0.75 mm high, 0.65 mm wide, jelly moderately thick, apical knob not present.

Velum very broad, stomach cylindrical or slightly tapering, less than half the length of bell, mouth simple, circular.

Gonads not developed at this stage. Four simple radial canals present, circular canal narrow, passing around the adaxial side of the marginal bulbs. Marginal bulbs large, with well developed ocelli.

Tentacles extensile, about same length as bell when fully extended, in contraction about same size as marginal bulbs, with regularly spaced clusters of nematocysts with a large capitate end. Scattered nematocysts on bell in interradial areas, concentrated mainly in the apical region.

Colour: Umbrella and tentacles colourless, stomach deep orange apically, grading through golden to almost colourless at mouth; marginal bulbs golden, ocelli deep orange.

Nematocysts of two types present in medusa:

— Stenoteles of same shape but larger than those of the hydroid, capsule 1 µm long, 8.5 µm wide,

— Very abundant ?microbasic euryteles, not discharged, 10 µm long, 5-7 µm wide.