Sphenolithus rioi


Classification: ntax_cenozoic -> Discoasterales -> Sphenolithaceae -> Sphenolithus -> S. conspicuus group -> Sphenolithus rioi
Sister taxa: S. anarrhopus, S. conspicuus, S. editus, S. rioi, S. villae

Taxonomy:

Citation: Sphenolithus rioi Agnini Fornaciari & Raffi 2008
Rank: Species
Synonyms: Sphenolithus sp. 1 Agnini et al. 2007
Taxonomic discussion: In the light microscope, S. rioi differs from S. anarrhopus (Pl.2, figs 13-16) in having a straight, and generally longer, apical spine. S. rioi differs from S. conspicuus Martini, 1976 in having a different apical spine: S. rioi has a triangular-shaped spine, whereas S. conspicuus is characterised by a slender, spearhead-shaped spine. [Agnini et al. 2008]

Distinguishing features: Medium-sized sphenolith with a prominent apical spine, extending symmetrically from the basal part.

Farinacci & Howe catalog pages: S. rioi *


Size: 4.5-7µm

Search data:
TagsLITHS: nannolith-radiate, circular, cylindrical, CA: process, CROSS-POLARS: R-prominent,
MetricsLith size: 4->7µm;
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: Rare from top NP5 to NP7, consistently present in NP8 according to Agnini et al (2007) who give detailed plot, as Sphenolithus sp. 1.
Last occurrence (top): at top of NP8 zone (100% up, 57.2Ma, in Thanetian stage). Data source: Agnini et al. 2007
First occurrence (base): in upper part of NP5 zone (80% up, 59.9Ma, in Selandian stage). Data source: Agnini et al. 2008

Plot of occurrence data:

References:

Agnini, C., Fornaciari, E., Raffi, I., Rio, D., Rohl, U. & Westerhold, T. (2007a). High-resolution nannofossil biochronology of middle Paleocene to early Eocene at ODP Site 1262: Implications for calcareous nannoplankton evolution. Marine Micropaleontology. 64: 215-248. gs

Agnini, C., Fornaciari, E. & Raffi, I. (2008). Three new species of calcareous nannofossil from Late Palaeocene and Early Eocene assemblages (Ocean Drilling Program Site 1262, Walvis Ridge, SE Atlantic Ocean). Journal of Nannoplankton Research. 30(1): 51-56. gs V O

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Sphenolithus rioi compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 20-4-2021

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