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Taxon
Gymnangium australimage Watson, 2005
Nomenclature
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Family: AglaopheniidaeGenus: Gymnangium
SUMMARY
Stem attached to hydrorhizal remnant; stem monosiphonic, unbranched, prosegment consisting of one short internode with two nematothecae, distal node transverse; internodes thereafter long, slender, smooth, nodes transverse, distinct, marked by a distal shoulder on internode.
Hydrocladia alternate, one per internode, not close, in one plane on opposite sides of stem, borne on distal third of internode on a short cylindrical apophysis, distal node of apophysis transverse; hydrocladium short with up to eight hydrothecae; no internal septa, nodes distinct, transverse.
Hydrotheca set at an angle of ca. 60°to internode, deeply seated in internode, saccate, divided abcaudally into two almost equal chambers by a strong partial septum passing downwards and slightly forwards from a deep indentation in abcauline wall, septum ending in a small knot of perisarc; adcauline wall of hydrotheca strongly convex. Margin (lateral view) with a small blade-shaped anterior cusp followed by three pairs of low cusps, embayments between shallow, a single sharp cusp between lateral nematothecae; in anterior view unpaired anterior cusp low, rounded, other cusps slightly everted, posterior cusp a low bulge in posterior margin.
Median nematotheca long, narrowly tubular, adnate almost to hydrothecal margin, free part curving away or sometimes following curve of margin, a shallow concavity in adcauline wall opposite intrathecal septum, aperture small, circular, a small secondary aperture just above hydrotheca. Lateral nematotheca very small, saccate, seated well below margin of hydrotheca, with a small tubiform neck and circular terminal aperture directed outwards to just beyond hydrocladial node, a larger secondary aperture facing upwards towards hydrotheca. Three cauline nematothecae similar to laterals, one behind apophysis, aperture facing outwards, one on internode above hydrocladium and one below, apertures facing upwards along internode.
Perisarc moderately thick relative to small size of stem.
Colour: pale buff.