Papposphaera sagittifera HET
P. sagittifera HET (Figs 4–16) The Arctic material from West Greenland (Fig. 7), North East Water Polynya (Figs 4–5, 13) and Svalbard (Figs 6, 8–12, 14–16) basically confirms what is already known about P. sagittifera HET from this region (Thomsen 1981). The rationale behind illustrating three compl...
| Main Authors: | , , |
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| Format: | Other/Unknown Material |
| Language: | unknown |
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Zenodo
2016
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| Subjects: | |
| Online Access: | https://doi.org/10.5281/zenodo.12534973 http://treatment.plazi.org/id/03EB512EFF99FF80FCA078969273B450 |
| Summary: | P. sagittifera HET (Figs 4–16) The Arctic material from West Greenland (Fig. 7), North East Water Polynya (Figs 4–5, 13) and Svalbard (Figs 6, 8–12, 14–16) basically confirms what is already known about P. sagittifera HET from this region (Thomsen 1981). The rationale behind illustrating three complete cells from TEM is to document the consistent presence of flagellation. The flagella and the haptonema typically curl up densely which renders measurements of these structures impossible. A haptonema is visible in e.g. Fig. 4 (arrow) where it is differentiated from the flagella by being significantly thinner. The apparent absence of flagellation in the numerous SEM illustrations of complete cells (Figs 10–12, 14) is bound to be an artefact somehow caused by the manipulation of the cells during filtration and subsequent drying. All complete cells illustrated from SEM clearly display organisms that have the typical cell polarity to be expected from a flagellated individual. Dimensional issues across the different regions are accounted for in Table 1. Central area calcification is invariable an axial cross in combination with a number of longitudinal bars evenly spread across the coccolith. The highest number of such bars observed is 7 (Fig. 8) which creates a densely packed central area. Most coccoliths tend to have 3–5 of these longitudinal bars (see e.g. Fig. 14). The calyx takes the shape of a four-winged rosette with the four wings positioned at right angles to each other (Figs 5–6, 9). Each wing has parallel sides. The exterior edge is straight, whereas the interior edge has a variable number of steps that gradually decrease the width of the wing towards the distal end (Fig. 3A). There seems to be a significant variability with respect to both the width of the wing and the number of steps on the interior edge. The degree to which the four-winged rosette diverges from the stem is dependent on the angle between the exterior edge and the line that proximally connects the inner and exterior edges of the wing. ... |
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