Aglaophenia pseudoplumosa Watson, 1997

Hydrorhiza a simple, thin tube reptant on algal thallus.

Hydrocauli flexuous, arising at rare intervals from the hydrorhiza.

Stems of same diameter as the hydrorhiza, short, monosiphonic, proximal half ahydrocladiate, a distinct V-shaped joint below proximal hydrocladium. Cauline internodes thereafter long and thin, nodes marked by a transverse constriction of the perisarc.

Hydrocladia alternate, arising from a short apophysis on front of the stem near middle of the internode. Internode with two short, conical cauline nematothecae, one above and one below the hydrocladial apophysis, both nematothecae with outwardly projecting orifices, deeply excavated on the adcauline side. Hydrocladia with 4 - 5 hydrothecae, internodes narrow, thinning at nodes; internode with four approximately equidistant faint transverse septa, the proximal septum extending into the hydrotheca as an intrathecal septum, distal septum situated below base of the lateral nematotheca.

Hydrotheca occupying entire internode, elongate, adcauline wall flat to biconvex, abcauline wall convex to base of the median nematotheca, intrathecal septum varying from a small notch in the adcauline wall to a delicate partition passing upward into the hydrotheca almost to base of the median nematotheca. Hydrothecal margin almost parallel or slightly oblique to internode, trumpet-shaped when viewed from above, in anterior view with two broad, strongly everted lateral lobes and a very prominent tongue-shaped anterior tooth, base of the tooth passing downward into the abcauline hydrothecal wall and connected to base of the median nematotheca by a triangular web of perisarc.

Median nematotheca narrow, tubular, adnate to the hydrotheca for more than half its length, free part extending outwards from the hydrotheca and inclined slightly forward, walls slightly swollen below a small circular terminal orifice and a large opening into base of the hydrotheca. Lateral nematothecae long, similar in shape to the median, projecting upward and forward in lateral view and away from the hydrotheca in anterior view, terminal orifice small, circular, with a second outward-facing orifice at junction with the hydrothecal margin.

Colour: Yellow.