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Taxon
Halecium luteum Watson, 1975
Nomenclature
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Family: HaleciidaeGenus: Halecium
SUMMARY
Colonies to 2.5 cm high, growth arborescent, main stem strongly fascicled, woody and stiff. Branching more or less in one plane, the ultimate branches in anyone part of the colony all directed anteriorly; in other parts they may face in other directions. Stem internodes of variable length, 0.40-0.65 mm, expanding distally, with 1, occasionally 2, extra nodes. Nodes distinct, oblique, parallel in each internode, sloping alternately left and right in adjacent internodes; perisarc indistinctly internally ridged. Width at proximal node, measured parallel to node, 0.12-0.14 mm.
Hydrophore seated on distal third of distal segment of internode, well below node. Hydrophore sessile, very flat and shallow, walls thin and strongly constricted just above diaphragm, abcauline wall more concave than adcauline. Margin circular, 0.14-0.16 mm in diameter, with outrolled rim. Depth from margin to punctae, 0.015-0.02 mm; depth from margin to diaphragm, 0.025-0.035 mm. Diaphragm very strong, with a distinct ring of punctae above, and a wedge shaped thickening of the perisarc of the internode below. Below the wedge the wall of the internode thins into a large circular fenestration from which the apophysis of a branch may arise.
Hydranth large with an annular hypostome and 25-28 tentacles.
Colour: bright yellow.