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Stylodictya aculeata Jørgensen, 1905

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Stylodictya aculeata:
Species very similar to foregoing [Stylodictya validispina]. Differentiated by greater irregularity of structure of shell, which has effect upon disposition of chambers, radial cross-pieces, needles, and pores. In addition, in S. aculeata width of chambers increases more markedly towards periphery of disk than in previous species. S. aculeata differs from S. validispina also in larger numbers of pores lying across width of one chamber (4-4.5).

Dimensions: diameter of middle chamber 15-17µ, diameter of first ring 30-35µ, of second about 55µm, of third about 80µm, of fourth 110-120µ, diameter of disk with five rings about 150µ.

Location: Found by Jørgensen (1905) in plankton off coast of Norway. In our Antarctic material located in sediment of stations lying south of 60°S lat., comparatively few and do not constitute fixed percentage of total number.

Note: Species S. validispina and S. aculeata are very similar to each other. Their morphological differences may prove to be due only to different hydrological conditions and that these are two subspecies of one polymorphic genus...


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