Mikriexoterikiaspida fionajacovidesiae Varol, 2025
From the Greek mikriexoterikiaspida, the small outer shield, refers to its narrower distal shield.
Circular to elliptical placolith consists of single-tiered distal and broader proximal shields and a double tube cycle gently protruding distally. Except for the outer tube cycle, all components exhibit inclined extinction lines and length-fast (-) elongation. The outer tube cycle shows constant extinction because the optic is vertical relative to the microscope stage in the plan view. The extinction lines are dextrogyre on the distal side, and their typical angle is about 73° on the distal shield and 48° on the tube cycle.
Mikriexoterikiaspida differs from Cyclagelosphaera, Watznaueria, and Ellipsagelosphaera because it has a narrower distal shield.
Varol, O. 2025a. A practical guide to optical studies of calcareous nannofossils. Grzybowski Foundation Special Publication. 29: 1-222