Classification: ntax_cenozoic -> Coccolithales -> Calcidiscaceae -> Hayaster
Sister taxa: Calcidiscus, Hayaster, Oolithotus, Umbilicosphaera, Cryptococcolithus, Hayella

Daughter taxa (time control age-window is: 0-800Ma)
Hayaster perplexus
n/a - monospecific
Hayaster sp.
Specimens which cannot be assigned to established species


Citation: Hayaster Bukry, 1973
Rank: Genus
Type species: Discoaster perplexus Bramlette & Riedel 1954
Taxonomic discussion: The Hayaster structure is essentially the same as Calcidiscus, but with reduced proximal shield. Only the one species H. perplexa has been described.

Distinguishing features: Coccoliths polygonal, thin; proximal shield much smaller than distal

Farinacci & Howe catalog pages: Hayaster *

Morphology: Placolith coccoliths with thin nearly flat distal shield, reduced number of rays and very small proximal; distal shield with straight sutures; dark in cross-polars.

Search data:
TagsLITHS: placolith, circular, CA: closed,
CSPH: equant, monomorphic, CROSS-POLARS: rim-unicyclic, V-prominent, R-prominent,
MetricsLith size: 5->15µm; Coccosphere size: 15->25µm;
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): near top of Selandian Stage (87% up, 59.5Ma, in Selandian stage). Data source: Total of range of species in this database

Plot of occurrence data:


Bown, P. R., Dunkley-Jones, T. & Young, J. R. (2007). Umbilicosphaera jordanii Bown 2005 from the Paleogene of Tanzania: confirmation of generic assignment and a Paleocene origination for the family Calcidiscaceae. Journal of Nannoplankton Research. 29(1): 25-30. gs V O

Bukry, D. (1973g). Phytoplankton stratigraphy, Deep Sea Drilling Project Leg 20, Western Pacific Ocean. Initial Reports of the Deep Sea Drilling Project. 20: 307-317. gs V O


Hayaster compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 1-3-2021

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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=641 Go to Archive.is to create a permanent copy of this page - citation notes

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