Discoaster bollii


Classification: Coccolithophores -> Discoasterales -> Discoasteraceae -> Discoaster -> D. exilis group -> Discoaster bollii
Sister taxa: D. exilis, D. cauliflorus, D. moorei, D. extensus, D. discissus ⟩⟨ D. bollii ⟩⟨ D. petaliformis, D. signus, D. apetalus

Daughter taxa: forms with different numbers of rays (blue => in age window 0-800Ma)
Discoaster pentabollii
5-rayed D. bollii
Discoaster quadribollii
4-rayed D. bollii
Discoaster tribollii
3-rayed D. bollii

Taxonomy:

Citation: Discoaster bollii Martini and Bramlette, 1963
Rank: Species
Variants: There is considerable variation in the ratio of central area width to arm length within D. bollii and Browning et al. (2017) record that long and short armd forms are routinely differentiated in their work. However, they also recorded that the two forms have identical ranges and intergrade and so they treated them as a single species. They do recommend separating speciemns with reduced numbers of rays as separate species, se table above. Other workers may prefer to use informal labels for these or to combine them in D. bollii.

Distinguishing features: Similar to D. exilis but with large distal boss, small proximal boss, and wide central-area, and usually smaller (<10µm).

Farinacci & Howe catalog pages: D. bollii * , D. pentabollii *


Size: 10-14 µm according to original descrition and this is typical of observed specimens, i.e. very large specimens do not seem to occur. 

Search data:
TagsLITHS: nannolith-radiate, star-shaped, CA: process, CROSS-POLARS: 1ou, V-prominent,
MetricsLith size: 10->15µm; Segments: 6->6;
Data source notes: size from OD & illustrated specs
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): in lower part of NN10 zone (20% up, 9.3Ma, in Tortonian stage). Data source: Browning et al. 2017
First occurrence (base): near base of NN9 zone (10% up, 10.4Ma, in Tortonian stage). Data source: Browning et al. 2017

Plot of occurrence data:

References:

Bergen, J. A. (1984). Calcareous nannoplankton from Deep Sea Drilling Project Leg 78A: evidence for imbricate underthrusting at the Lesser Antillian active margin. Initial Reports of the Deep Sea Drilling Project. 78A: 411-445. gs V O

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 V O

de Kaenel, E. & Villa, G. (1996). Oligocene-Miocene calcareous nannofossil biostratigraphy and paleoeecology from the Iberian Abyssal Plain. Proceedings of the Ocean Drilling Program, Scientific Results. 149: 79-145. gs V O

Martini, E. & Bramlette, M. N. (1963). Calcareous nannoplankton from the experimental Mohole drilling. Journal of Paleontology. 37(4): 845-855. gs

Müller, C. (1974b). Calcareous nannoplankton, Leg 25 (Western Indian Ocean). Initial Reports of the Deep Sea Drilling Project. 25: 579-633. gs V O

Perch-Nielsen, K. (1972b). Remarks on Late Cretaceous to Pleistocene coccoliths from the North Atlantic. Initial Reports of the Deep Sea Drilling Project. 12: 1003-1069. gs V O

Theodoridis, S. (1984). Calcareous nannofossil biostratigraphy of the Miocene and revision of the helicoliths and discoasters. Utrecht Micropaleontological Bulletin. 32: 1-271. gs V O

Wei, W. (2003). Upper Miocene nannofossil bistratigraphy and taxonomy of Exxon core CH30-43-2 from the Gulf of Mexico. Journal of Nannoplankton Research. 25(1): 17-23. gs V O

Young, J. R. (1998). Neogene. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 225-265. gs V O


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Discoaster bollii compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 24-11-2020

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Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=455 Go to Archive.is to create a permanent copy of this page - citation notes



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