Sphenolithus pseudoheteromorphus

Classification: ntax_cenozoic -> Discoasterales -> Sphenolithaceae -> Sphenolithus -> S. heteromorphus group -> Sphenolithus pseudoheteromorphus
Sister taxa: S. heteromorphus, S. milanetti, S. preasii ⟩⟨ S. belemnos ⟩⟨ S. pseudoheteromorphus, S. conicus, S. calyculus ⟩⟨ S. delphix, S. microdelphix, S. spinula


Citation: Sphenolithus pseudoheteromorphus Fornaciari & Agnini 2009
Rank: Species
Taxonomic discussion: The species was first mentioned by Rio et al. (1990) and Fornaciari et al. (1990), in the proceedings of ODP Leg 115, but it was not formally described until Fornaciari & Agnini (2009).

Distinguishing features: Similar to S. heteromorphus but base has more elements including a few almost parallel with the spine; spine slightly asymmetric

Farinacci & Howe catalog pages: S. pseudoheteromorphus *

Morphology: Very similar to S. heteromorphus and easily confused with it but the spine is less symetric and less regularly formed than in S. heteromorphus 

Ecology & Biogeography: Reported from Western Equatorial Pacific, Indian and Atlantic Oceans (Fornaciari & Agnini 2009)

Search data:
TagsLITHS: nannolith-radiate, circular, cylindrical, CA: process, CROSS-POLARS: V-prominent, R-prominent,
MetricsLith size: 4.5->12µm;
Data source notes: lith height from OD
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Notes: S. pseudoheteromorphus occurs below S. belemnos and their ranges overlap (see e.g. Fornaciari et al. 1990), some authors may have included S. pseudoheteromorphus in S. belemnos.
Fornaciara et al. (2009) report the species as being confined to a short zone at the top zone CN1c of Okada & Bukry with the FO occuring within magnetochron C6n
Last occurrence (top): within CN1c subzone (19.03-22.82Ma, top in Burdigalian stage). Data source: original description
First occurrence (base): within chron C6n sub-Magnetochron (18.75-19.72Ma, base in Burdigalian stage). Data source: original description

Plot of occurrence data:


Bergen, J. A., de Kaenel, E., Blair, S. A., Boesiger, T. M. & Browning, E. (2017). Oligocene-Pliocene taxonomy and stratigraphy of the genus Sphenolithus in the circum North Atlantic Basin: Gulf of Mexico and ODP Leg 154. Journal of Nannoplankton Research. 37(2-3): 77-112. gs V O

Fornaciari, E. & Agnini, C. (2009). Taxonomic note: Sphenolithus pseudoheteromorphus, a new Miocene calcareous nannofossil species from the equatorial Indian Ocean. Journal of Nannoplankton Research. 30(2): 97-101. gs V O

Fornaciari, E., Raffi, I., Rio, D., Villa, G., Backman, J. & Olafsson, G. (1990). Quantitative distribution patterns of Oligocene and Miocene calcareous nannofossils from the western equatorial Indian Ocean. Proceedings of the Ocean Drilling Program, Scientific Results. 115: 237-254. gs V O


Sphenolithus pseudoheteromorphus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 15-4-2021

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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=1315 Go to Archive.is to create a permanent copy of this page - citation notes

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