Nannotax3 - ntax_cenozoic - flat-topped Nannotax3 - ntax_cenozoic - flat-topped


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

Daughter taxa (time control age-window is: 0-800Ma)Granddaughter taxa
Helicosphaera HOL
Monomorphic; liths solid - formed of layers of crystallites in rhomboid array
Coccolith distal surface with central boss and varying number of depressions.
Helicosphaera HOL catilliferus type
Helicosphaera HOL confusus type
Helicosphaera HOL ponticuliferus type
Helicosphaera pavimentum HOL

Holococcolithophora -flat
Monomorphic - cavate
Coccoliths with broad rim and recessed distal cover without boss
Holococcolithophora cialdii
Holococcolithophora dentata

S. aurisinae HOL type
Dimorphic - liths cavate
BCs flat topped with large openings in tube and variable openings in distal surface; tiered wall fabric; low transverse ridge.
CFCs helladoliths - ridge of BCs is extended into prominent leaf, no openings in tube.
Syracosphaera aurisinae HOL
Syracosphaera gaarderae HOL
Syracosphaera isselii HOL
Syracosphaera magnaghii HOL
S. aurisinae HOL type sp.

S. mediterranea HOL type
Dimorphic - usually cavate
BCs with flat distal cover with or without openings; central boss
CFCs; with irregular bridge or distal cover arched upwards
Calyptrolithina multipora
Syracosphaera histrica HOL
Syracosphaera mediterranea HOL gracillima type
Syracosphaera mediterranea HOL hellenica type
Syracosphaera mediterranea HOL marisrubri type
Syracosphaera mediterranea HOL wettsteinii type

Dimorphic; liths semi-solid - formed of concentric rings of crystallites.
BCs flat topped with node or ridge on distal surface, rather than a true bridge.
CFCs similar with transverse bridge or leaf.
Syracosphaera bannockii HOL
Zygosphaera amoena
Zygosphaera marsilii
Zygosphaera sp.


Citation: Holococcoliths with flat cover over the tube - informal grouping proposed by Young et al., 2003
taxonomic rank: informal group of genera

Distinguishing features:
Parent taxon (Holococcoliths): Haploid life-cycle stages, with liths formed of numerous rhombohedral microcrystals
This taxon: Holococcoliths with tube, covered distally by a flat cover

Farinacci & Howe catalog pages: flat-topped [no catalog entry yet]

Search data:
Lith size: 1.6->3.3µm;
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): Extant. Data source: Total of ranges of the species in this database
First occurrence (base): within Quaternary Period (0.00-2.59Ma, base in Gelasian stage). Data source: Total of ranges 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. S1: 1-132. gs


flat-topped compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 26-5-2024

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

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