Thuiaria plumularioides Watson, 2000

Hydrorhiza a knot of tubes entwining substrate. Stems to 25 mm high, straight, robust, pinnate, proximal part of stem ahydrocladiate but with two rows of opposite hydrothecae; ahydrocladiate part of stem usually with a strong distal hinge joint. Cauline nodes of hydrocladiate part of stem distinct, slightly oblique to transverse; internode with three hydrocladia, one to three hydrothecae above hydrocladium, proximal one axillar, distalmost level with node. Cauline perisarc very thick proximally, thinning a little distally.

Hydrocladia close set, alternate, long, arching gracefully upwards at an angle of c. 30° to cauline axis from a strong apophysis with an indistinct transverse constriction and a pronounced distal hinge joint. Hydrocladial internodes long, nodes distinct hinge joints.

Hydrothecae biseriate, frontal on hydrocladium, proximal internodes bearing up to 10 pairs of hydrothecae, pairs becoming fewer distally; hydrothecae overlapping, facing upwards, sub-opposite on proximal region of hydrocladium, becoming opposite distally, each pair overlapping base of pair above. Hydrotheca long, tubular (lateral view), almost vasiform (anterior view), slightly tumid at base , narrowing just behind margin, adcauline walls joined, straight, a short convex length free of internode at a sharp outward distal bend; abcauline wall almost straight, a prominent abcauline submarginal shelf, a foramen at base of wall connecting with internode, base of hydrotheca rounded. Aperture oval, margin thickened with a pair of opposite laterally placed cusps and a rounded adcauline lobe; opercular valve attached to submarginal adcauline shelf.

Hydranth with an abcauline caecum and about 10 tentacles.

Colour: pale yellow.