Classification: Coccolithophores -> Holococcoliths -> septate
Sister taxa: tubeless, convex, bridged, flat-topped, septate, open-tube, fossil holococcoliths, U. extant holococcolith,

Daughter taxa: (blue => in age window 0-800Ma)
Internal walls define 4-6 pores. Tube 10-15 crystallites high, castellated, higher where it meets internal walls. Tube sometimes double-layered, base open.
Liths similar to quadriperforatus but larger (3-4 µm), with more pores (8-20) and lacking castellations; single irregular boss near centre of lith
Solid, disk-shaped coccolith with several irregular deep depressions; formed of single block of crystalites with sub-vertical c-axes; no outer wall/tube; one or two irregular knobs on long axis.
Coccoliths with area inside tube almost filled by concentric walls, distal surface ornamented by 10-15 pyramidal bosses.
Liths similar to S. quadriperforatus but more delicate and with open hexagonal mesh fabric.
Liths similar to S. quadriperforatus but walls double layered with open hexagonal mesh fabric.


Citation: Holococcoliths with internal septae - informal grouping proposed by Young et al., 2003
Rank: informal grouping

Distinguishing features: Holococcoliths with tube, open distally and subdivided internally by vertical septae

Farinacci & Howe catalog pages: septate [no catalog entry yet]

Morphology remarks: Coccospheres monomorphic, coccoliths are open tubes with internal septae (walls), extending down to proximal surface. The tube wall shows hexagonal fabric and the crystallites have radial c-axes (birefringent in plan view in LM). The fabric of the septae is not obviously different but they are non-birefringent in plan view in LM and so the calcite crystallites must have vertical c-axes.
This is a distnictive ultrastructure and although most species have been placen in Syracolithus it is quite different tothe other species tradtionally placed in Syracolithus).

Evolution & Phylogeny: Young et al. (2003) predicted that holococcolihs with this structure would proved to be closely related, and so produced by the Calcidiscaceae. However, Frada et al. (2009) showed that some of them were produced by the Pontosphaeraceae, and so this holococcolih structure has almost certainly evolved at least twice.

Biology & life-cycles: Produced in the haploid phase of Calcidiscaeae (Calcidicus leptoprus ssp. quadriperforatus) and Pontosphaeraceae (

Search data:
TagsLITHS: holococcolith, flaring distally, tubular, elliptical,
MetricsLith size: 1.8->4µm;
The morphological data given here can be used on the advanced search page. See also these notes

See also: septate ;

Geological Range:
Last occurrence (top): Extant Data source: Total of range of species in this database
First occurrence (base): at base of Ypresian Stage (0% up, 56Ma, in Ypresian stage). Data source: Total of range of species in this database

Plot of occurrence data:


Young, J. R., Geisen, M., Cros, L., Kleijne, A., Probert, I. & Ostergaard, J. B. (2003). A guide to extant coccolithophore taxonomy. Journal of Nannoplankton Research, Special Issue. 1: 1-132. gs


septate compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 19-10-2019

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Short stable page link: Go to to create a permanent copy of this page - citation notes

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