Ilselithina


Classification: ntax_cenozoic -> Coccolith families inc sed -> Coccolith genera inc sed -> Ilselithina
Sister taxa: Aliculosphaera, Biantholithus, Camuralithus, Centumgemina, Ellipsolithus, Gladiolithus, Ilselithina, Leesella, Pedinocyclus, Petasus

Daughter taxa (time control age-window is: 0-800Ma)
Ilselithina fusa
Proximal shield without slits between the elements; distal shield elements delicate, tips well separated
Ilselithina iris
Proximal shield with slits between the elements; distal shield elements robust, tips touch.
Ilselithina sp.
Specimens which cannot be assigned to established species

Taxonomy:

Citation: Ilselithina Stradner in Stradner and Adamiker, 1966
Rank: Genus
Type species: Ilselitina iris Stradner, 1966
Taxonomic discussion: Assignment to Coccolithaceae is tentative

Distinguishing features: Placolith-like coccoliths, with distal shield reduced to ring of spines.

Farinacci & Howe catalog pages: Ilselithina *


Morphology: Usually seen in side view, and in this orientation it is clear that the whole coccolith is formed of a single cycle of elements, with sub-vertical C-axes.

Size: Small to minute coccoliths (2-5 µm). I. fusa (3-5) µm) is larger than I. iris (2-3 µm)


Phylogenetic relations: Often placed in the Coccolithaceae since they are placoliths and clearly do not have reticulofenestrid structure. However, the coccoliths are formed of a single cycle of elements (this is quite clear in side view in LM) rather than separate V and R cycles and there is no real structural similarity to Coccolithaceae, or Calcidiscaceae.
Intriguingly they are rather similar to the heterococcoliths of Ceratolithus (formerly known as Neosphaera), so it is conceivable that they are the alternate life-cycle stage of Triquetrorhabdulus carinatus

Search data:
TagsLITHS: placolith, circular, CROSS-POLARS: rim-unicyclic, R-prominent,
MetricsLith size: 2->5┬Ám;
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 Burdigalian Stage (32% up, 19Ma, in Burdigalian stage). Data source: Total of range of species in this database
First occurrence (base): near top of Priabonian Stage (86% up, 34.4Ma, in Priabonian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Stradner, H. & Adamiker, D. (1966). Nannofossilien aus Bohrkernen und ihre elektronenmikroskopische Bearbeitung. Erdoel-Erdgas Zeitschrift. 82: 330-341. gs


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

Taxon Search:
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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=754 Go to Archive.is to create a permanent copy of this page - citation notes



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