Nannotax3 - ntax_cenozoic - flat-topped

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

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

Poricalyptra
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.
Poricalyptra isselii
Poricalyptra magnaghii
Syracosphaera aurisinae HOL
Syracosphaera gaarderae HOL
Poricalyptra 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

Zygosphaera
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.

Taxonomy:

Citation: Holococcoliths with flat cover over the tube - informal grouping proposed by Young et al., 2003
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]


Morphology:


Size:


Ecology & Biogeography


Biology & life-cycles

Phylogenetic relations

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 range of species in this database
First occurrence (base): at base of Gelasian Stage (0% up, 2.6Ma, in Piacenzian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

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 V O


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flat-topped compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 1-12-2022

Taxon Search:
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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=581 Go to Archive.is to create a permanent copy of this page - citation notes



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