Watznaueria gresslyi

Ellipsagelosphaera gresslyi Grün & Zweili, 1980

Elliptical species of Watznaueria are characterised by single-tiered distal and proximal shields, narrow tube cycles, and a broad, elongate central opening devoid of central-area structures. The central opening exceeds 1.5 μm in width and has an ellipticity greater than 1.5.

Under cross-polarised light in plan view, the shields and tube cycles exhibit white interference colours, inclined extinction lines, and length-fast (–) elongation. Extinction angles measured on the distal side are approximately 75° in the shields and 71° in the tube cycles. The locking cycle remains in constant extinction, forming a narrow dim suture between the shield and tube cycle.

Grün, W. & Zweili, F. 1980. Das kalkige Nannoplankton der Dogger-Malm-Grenze im Berner Jura bei Liesberg (Schweiz). Jahrbuch der Geologischen Bundesanstalt. 123: 231-341.