Symmetrikiexafanisi cubaensis

Symmetrikiexafanisi cubaensis Varol, 2025

Small (often less than 6.0 μm) species of Symmetrikiexafanisi have a moderately high proximal cycle, an extremely thin lateral cycle, and twin apical spines joined along their entire length. A short supplementary segment between the apical spines is visible only when the specimen length is 45° under XPL in well-preserved specimens. The maximum width of the species is at the base of the apical spine.

Optical Properties: From the side view, the apical spines and the segments of the proximal cycle exhibit symmetrical extinctions. The lateral cycle displays parallel extinction and length-fast (-) elongation from the side view. Under XPL, when the specimen is oriented at 45°, the lateral cycle, supplementary segment, and a segment of the proximal (observed from its length) cycle create a cross in well-preserved specimens.

Symmetrikiexafanisi cubaensis differs from Symmetrikiexafanisi magnifica in that it is smaller and has an indistinct shorter supplementary segment.

Varol, O. 2025. A practical guide to optical studies of calcareous nannofossils. Grzybowski Foundation Special Publication, 29, 230 pp.