Watznaueria eurycycla
Set number: 3221
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10µm
Watznaueria sp.2
Large species of Watznaueria (>8.0 μm) are characterised by an exceptionally broad tube cycle and very narrow shields, leaving only a diminutive central opening less than 0.5 μm in diameter.
From the Greek eurys, broad, wide and kyklos, circle, cycle, referring to the exceptionally broad tube cycle.
Under cross-polarised light in plan view, the species displays white interference colours, inclined extinction lines, and length-fast (–) elongation. On the distal side, the extinction angle in the shields is approximately 67°. This angle cannot be measured directly in the tube cycles because of the oblique orientation of their constituent elements; however, the apparent angle between extinction directions in the tube cycle is approximately 58°, corresponding to an element obliquity of approximately 32°.
The locking cycle exhibits interference colours and produces a transitional boundary between the tube cycle and the shield. Variation in the orientation of extinction lines within the tube cycle allows the inner and outer tube cycles, which are of equal width, to be recognised.