Aglaophenia carinifera Bale, 1914

Stems to 150 mm high, unbranched, pinnate, lax, fascicled.

Hydrorhiza a knotted bunch of stolons; stolons becoming parallel polysiphonic tubes of lower two thirds of stem; distal stem region monophonic. Stem internodes short, slightly oblique, indistinct; basal third of stem ahydrocladiate.

Hydrocladia to 20 mm long, close, alternate, lax, one per stem internode, given off one above other from frontal tube of stem; hydrocladial internodes short, nodes slightly oblique; two partial septa, one below intrathecal septum, the other below base of lateral nematotheca.

Hydrothecae seated on hydrocladium at an angle of ca. 40°, base elliptical, rather narrow, walls expanding to margin, a weak, usually partial intrathecal septum passing up into hydrotheca from base. Margin with a prominent anterior incisor-like cusp projecting slightly beyond line of margin, followed by three pairs of cusps; the first long, sharp and outwardly pointed (anterior view), the last pair low, rounded.

Median nematotheca short, broad, not quite reaching hydrothecal margin, adnate to hydrotheca to base of anterior cusp, abcauline wall parallel with curve of hydrotheca, free wall short, terminal aperture open down to hydrotheca. Lateral nematothecae parallel to axis of hydrotheca, almost tubular but slightly wider at base, aperture small. circular, level with margin of hydrotheca, a deeply excavated If-shaped secondary aperture connecting with hydrotheca. Cauline nematotheca large, same size and shape as laterals, one above hydrocladium and the other below.

Corbulae abundant, five or six on stem; corbula replacing a hydrocladium, gonohydrocladium long, slender, with two proximal hydrothecae; corbula closed by 13-17 overlapping leaflets, each leaflet flaring outwards from body, anterior edge fringed by nematothecae of same shape as laterals but with large U-shaped aperture; width of fringe reducing distally along corbula, apex of corbula a blunt spine with several smaller nematothecae, a single nematotheca at apex; basal nematotheca on each leaflet pointing downwards away from spine of corbula.

Colour: Stems pale shining brown, hydrocladia and corbulae yellow-brown, gonophores yellow.