Nannotax Enabling nannofossil research

Description: Coccospheres - Monothecate, dimorphic, motile. Body coccoliths flangeless muroliths; rims formed of an outer cycle of strongly imbricate (anticlockwise) elements and an inner cycle of vertical elements. Central area with two radial laths per rim element and central plaque formed of two plates. Circum Flagellar Coccoliths similar but slightly smaller, with low spine.

Remarks: Coronosphaera is usually placed in the family Syracosphaeraceae, but has also been considered a genus incertae sedis within the order Syracosphaerales.. It is distinguished from Syracosphaera by

• the strong imbrication of the rim elements
• the occurrence of two laths per rim
• Absence of flanges
• Absence of exothecal coccoliths.

References: Gaarder & Heimdal (1977) - morphology; Geisen et al. (2002) - holococcolith associations; Houdan et al. (2004) - culture observations.

Type species: C. mediterranea.

LM: Isolated body coccoliths typically show a narrow rim with high birefringence and strongly curved isogyres. The central area is weakly birefringent and shows tangential orientation (so blue and yellow sectors show the opposite to normal disposition) and two central elements.