Nannotax

Description: Coccolith structure - dome-shaped, formed of layer of crystallites in hexagonal array with the crystallographic c-axis perpendicular to the surface. In LM the rim is bright and central part dark.

Coccospheres weakly dimorphic, piriform.

Coccolith form - tube about 10 crystallites high, tiered wall fabric; basal flange;
distal cover recessed into tube, domal with ring of 8-10 pores around
contact with tube; internal ridges surround pores in at least some
specimens. Circum-flagellar coccoliths more elevated and with pyramidal central boss.

Remarks:

Size: Liths 2-3 µm long.

Life-cycle association: The association of these holococcoliths with Syracosphaera pulchra has been demonstrated by observation of numerous combination coccospheres, Cros et al. (2000), Geisen et al. (2002). Saugestad & Heimdal (2002). oblonga-type holococcoliths also occur in assocaition with S. pulchra and this is interpreted as a result of pseudo-cryptic specieation (Geisen et al. 2002).

Fossil record: Can be common in well-preserved Quaternary sediments (Crudeli et al. 2006).

Synonyms:

• Calyptrosphaera pirus Kamptner 1937
• Daktylethra pirus (Kamptner 1937) Norris 1985