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Taxon Pages
Hyalonema (Ijimaonema) clavigerum Schulze, 1886
Nomenclature
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Genus: HyalonemaSubgenus: Hyalonema (Ijimaonema)
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Synonyms: 3
SUMMARY
Shape and size: The fragment found represents about one-eighth of the whole body, and is without any trace of the basal tuft, but still exhibits a portion of the oscular margin and one of the racial septa. The consistence of this sponge fragment, which is about 5 cm long, and represents a probably truncated oval body, is not so great as that of Hyalonema (Ijimaonema) globus.
Surface: The whole external surface distinctly exhibits a well-developed rectangular dermal framework.
Skeletal elements: The parenchymal skeleton consists again of somewhat large smooth and radially disposed oxyhexacts, and of simple oxydiacts which are either smooth, or have a median swelling or four projecting median knobs. Between these, thin forms equipped at both ends with delicate barbs occasionally occur, like those found abundantly in the parenchyma of Hyalonema (Ijimaonema) globus.
The dermal skeleton is mainly composed of somewhat large smooth hypodermal oxypentacts, with oblique, inwardly directed tangential rays. On the outer surface numerous autodermal pentact pinuli occur, with rather long, smooth and pointed, basal tangential rays, while the relatively short distal ray bears, as in Hyalonema (Ijimaonema) globus, long, fine, upwardly bent lateral spines, and a knob-like external terminal portion with thick, somewhat pointed axial end, and so has a tufted appearance.
The somewhat large amphidiscs which are irregularly scattered in radial disposition within the external skin, exhibit a firm smooth axial rod with several (four or eight) radially projecting tubercles in the centre. The bell-shaped terminal umbels are rather broad, and measure about one-fourth of the total length. They consist of eight broad shovel-shaped rays with lancet-like pointed ends. There is a much sparser occurrence of rather small elongated forms, with narrow umbel-rays. Very frequent, on the other hand, is the occurrence of the familiar small amphidiscs with ten- or twelve-rayed, short, hemispherical umbels.
In the gastral membrane and in the lining of the larger efferent canals the hypogastral oxypentacts are absent, but strands of oxydiacts of various thickness, with or without central thickening and projecting nodes occur abundantly. The autogatral pentact pinuli are strikingly distant from one another, and bear long, pointed, somewhat spinose basal rays, and a rather long spindle-shaped, thickened proximal with short, almost scale-like teeth. Small amphidiscs with twelve- or more rayed, short, hemispherical umbels occur abundantly in the gastral membrane. The cuff-like limiting fringe round the sharply defined oscular margin consists of oxydiacts, almost 1 mm long, in which the proximal ray is quite smooth and simple, and uniformly narrowed into a sharp point, while the free distal ray, close above the smooth inner portion, is beset in fir-tree like fashion with scale-like or pointed spines, projecting obliquely outwards, and also exhibits a spindle-shaped thickening.