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Taxon
Gymnangium aureum (Watson, 1973)
Nomenclature
-
Family: AglaopheniidaeGenus: Gymnangium
SUMMARY
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.