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Taxon
Lytocarpia orientalis (Billard, 1908)
Nomenclature
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Family: AglaopheniidaeGenus: Lytocarpia
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Synonyms: 3
SUMMARY
Stems simple, plumose, to 50 mm high, arising from a thin, reptant hydrorhiza embedded in fine sediment. Stem fascicled, prosegment consisting of many parallel tubes, becoming monosiphonic distally, perisarc thick; proximal stem ending in a pronounced blade- shaped hinge joint, blades connected by a thin web of perisarc. Entire length of fascicular tubes other than axillar tube with a row of closely spaced ovoid nematothecae; axillar tube unsegmented, giving off hydrocladia at an angle of c. 30° to axis.
Hydrocladial apophysis short, distal node transverse, indistinct, internodes thereafter moderately long, perisarc smooth, thick, nodes merely a faint thinning of perisarc; three equidistant partial intranodal septa below hydrotheca, proximal septum short, mid-septum longer, curved forwards, distal septum straight or curved backwards from base of lateral nematotheca.
Hydrotheca entirely adnate to internode, body semi-ovoid, tilted upwards at an angle of c. 30° to internode, posterior adcauline wall deeply sunk in internode, a short plug-like extension of the middle intranodal septum passing into hydrotheca from summit of an upward bulge in internode; abcauline wall weakly convex to sinuous, a slight concavity behind margin. Margin transverse to hydrothecal axis, mesial abcauline cusp prominent, sharply pointed, followed by three pairs of very shallow, scalloped cusps; margin straight between lateral nematothecae; perisarc of hydrotheca thin, thickening a little below margin.
Mesial nematotheca completely adnate to hydrotheca, terminating below margin, orifice sinuate, open down to hydrotheca; lateral nematotheca conical, widening to deep gutter-shaped orifice, open to internode. Cauline nematothecae same as laterals, orifice large, one above hydrocladium, facing upwards along stem axis and one below, facing along hydrocladium, a large circular mamelon between; nematothecae on polysiphonic tubes of stem ovoid.
Colour: Stem honey brown; hydrocladia lemon yellow.