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Taxon
Macrorhynchia mulderi (Bartlett, 1907)
Nomenclature
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Family: AglaopheniidaeGenus: Macrorhynchia
SUMMARY
Proximal stem long, ahydrocladiate, segmented by several obscure transverse septa, distal end of ahydrocladiate caulus with a single, or double large V-shaped joint; stem thereafter hydrocladiate. Cauline perisarc thick and smooth, internodes short, nodes transverse with an indistinct shoulder, hydrocladia alternate, one slightly frontal on each internode. Cauline apophysis moderately long with a strongly contracted distal node.
Hydrocladia with 6–8 hydrothecae; hydrotheca occupying entire hydrocladial internode, node transverse, distinct; two internal hydrocladiate intermodal septa, one complete, directed obliquely backwards from posterior third of base of hydrotheca, the other partial to complete, directed distally forwards from base of lateral nematotheca to node.
Hydrotheca almost tubular, at an angle c. 20° to hydrocladial axis, body divided into an ovoid posterior third by a forwardly curved complete septum connecting with hydrocladial septum, a quadrangular thinning of tissue at junction of septa. Margin of hydrotheca complexly and deeply cuspate, in lateral view anterior cusp scimitar-shaped, followed by a deep cusp, separated from the next cusp by a shallow embayment, the second cusp appearing more rounded than the first, followed by a long, inwardly curved posterior cusp identical with the anterior; a long boat-shaped foramen extending from junction of median nematotheca with hydrotheca to base of anterior cusp. In anterior view anterior cusp large, wide, blunt or sometimes shallowly lobate, the next cusp more sharply pointed than seen in lateral view, the next and outer ones bilobate (the latter responsible for the scimitar shape in lateral view).
Median nematotheca short, tubular, distal end directed away from hydrotheca, terminating well below hydrothecal margin, abcauline wall weakly sinuous, terminal orifice circular to lobate; lateral nematothecae tubular, pointing forward, narrowing distally to a small circular orifice behind hydrothecal margin, a small secondary basal orifice at junction with hydrotheca. One cauline nematotheca same as laterals on stem internode below apophysis.
Gonosome comprising 2 gonophores-1 male and 1 female, in an open corbula arising from a primary hydrocladium.
Primary hydrocladium with thecate proximal internode, followed by a swollen internode bearing 3 nematocladia and gonophores.
Nematocladia 0.75-0.84 mm long (but may be broken) each bearing a single row of nematothecae.
Gonothecae round, laterally compressed; female, 1.35 mm in diameter, slightly larger than male, packed with mature ova, blastostyle almost filling gonothecal cavity; male gonophore surrounded by a blastostyle of the same shape, but of smaller size than the female.