Holotype: NMV 02088, microslide; G2107, preserved material, remainder of holotype colony. On rock wall, rough water side, Pearson Island, South Australia, 33 m [33°57'S, 134°15'E].
Paratypes: G2089, microslide, G2108, preserved material, remainder of colony; G2090, microslide, G2109, preserved material, remainder of colony; SAM microslide.
The marginal thecal teeth exhibit the variations in length and shape characteristic of Gymnangium. The teeth are normally long, the middle tooth being the longest of the 3 on each side. The median nematothecae are all of nearly equal size, and show little tendency towards increase in length in the distal region of the hydrocladium.
Rootstock small, fibrous.
Stem monosiphonic, lower stem 1 mm in diameter, athecate, divided into internodes, nodes transverse, proximal internodes with circular pits where cauline nematothecae have dropped off. First branch 2 cm above base, all branching thereafter dichotomous, at an angle of about 40°, the branches becoming somewhat convergent distally, then rebranching. Branching repeated 6-7 times, always in the one plane. Branch internodes short, 0.60-0.69 mm, divided by indistinct transverse nodes, diameter at node, 0.66-0.84 mm.
Hydrocladia to 5 mm long, alternate, 2 on an internode, given off after first branching of main stem, standing out stiffly at an acute angle from the branch, giving the colony a decidedly "front and back" aspect. Hydrocladial internodes 0.28-0.31 mm long, nodes almost perpendicular to the axis, indistinct, no internodal septa.
Hydrothecae squat, set at an angle of 50° to hydrocladium, 0.23-0.26 mm deep, filling internode; adcauline wall straight, fixed part 0.12-0.14 mm long, free part 0.03-0.05 mm long; abcauline wall 0.17-0.19 mm long, divided in the middle by a long intrathecal ridge projecting slightly forward more than half way across thecal cavity; base of hydrotheca flat, with a small knot of denticles on the adcauline side marking the hydropore. Margin 0.17-0.29 mm in diameter, with 8 teeth-3 pairs of prominent bluntly pointed teeth, the middle pair the longest, outwardly bent, the anterior pair erect, the posterior pair slightly everted; 1 low posterior tooth, often obsolete, and 1 small anterior tooth below the median nematotheca.
Median nematothecae almost twice the height of the hydrotheca, 0.28-0.40 mm long, 0.05-0.07 mm wide at base, tapering distally and inclined forward, terminal aperture small, circular, lateral aperture distinct. Lateral nematothecae small, 0.11-0.13 mm long, saccate, not reaching thecal margin, 1 small terminal aperture on a short outwardly turned neck, and 1 lateral aperture facing inward towards the hydrotheca.
Colour: Amber.
Southern Australia (South Australia, Victoria, Western Australia).
Subtidal, on rock faces exposed to surge.