Discoaster prepentaradiatus prepentaradiatus


Classification: Coccolithophores -> Discoasterales -> Discoasteraceae -> Discoaster -> D. pentaradiatus group -> Discoaster prepentaradiatus -> Discoaster prepentaradiatus prepentaradiatus
Sister taxa: D. prepentaradiatus prepentaradiatus, D. prepentaradiatus plautus, D. styzenii, D. trifolius,

Taxonomy:

Citation: Discoaster prepentaradiatus ssp. prepentaradiatus Bukry & Percival 1971
Rank: species
Synonyms:
Notes & discussion: Subdividing prepentaradiatus into subspecies was introduced in Browning et al. (2017), however the name D. prepentaradiatus ssp. prepentaradiatus is an autonym and so retains the holotype and authorship of the original description. Separating the two morphotypes has obvious logic since they are quite distinct and it is dificult to adequately describe the species without explicitly describing the two forms. However, they have very similar ranges and intermediate speciemens occur, so they are unlikely to represent discrete biological species. 

Distinguishing features: Form with slender bifurcations

Farinacci & Howe catalog pages:


Morphology remarks: Typically this form has long slender bifurcations diverging at an acute angle, relative slender rays and small central area. It superficially resembles D. pentaradiatus, but they can easily be distinguished by use of cross-polarised light; on D. pentaradiatus specimens the 5-rays behave as separate crystal units whereas on D. prepentaradiatus (and all other discoasters) the whole specimen behaves as one crystal unit. 
 

Search data:
TagsLITHS: nannolith-radiate, star-shaped, V-UNITS: V-prominent, DETAILS: 1ou,
MetricsLith size: 0->0µm;
Sources:
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): near top of NN10 zone (91% up, 8.4Ma, in Tortonian stage). Data source: Browning et al 2017
First occurrence (base): in mid part of NN9 zone (46% up, 10.1Ma, in Tortonian stage). Data source: Browning et al 2017

Plot of occurrence data:

  • (NB There is no histogram as there are no occurrence records for the taxon in the Neptune database) Parent: Discoaster prepentaradiatus

    References:

    Browning, E., Bergen, J. A., Blair, S. A., Boesiger, T. M. & de Kaenel, E. (2017). Late Miocene to Late Pliocene taxonomy and stratigraphy of the genus Discoaster in the circum North Atlantic Basin: Gulf of Mexico and ODP Leg 154. Journal of Nannoplankton Research. 37(2-3): 189-214. gs

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    Discoaster prepentaradiatus prepentaradiatus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 19-2-2020

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