Nannotax3 - ntax_cenozoic - C. leptoporus group Nannotax3 - ntax_cenozoic - C. leptoporus group

C. leptoporus group


Classification: ntax_cenozoic -> Coccolithales -> Calcidiscaceae -> Calcidiscus -> C. leptoporus group
Sister taxa: C. leptoporus group, C. pacificanus group, C. sp.

Daughter taxa (time control age-window is: 0-800Ma)Granddaughter taxa
extant species
Calcidiscus leptoporus
Coccoliths circular to sub-circular, central-area closed, >5 µm
Calcidiscus leptoporus subsp. leptoporus
Calcidiscus leptoporus subsp. quadriperforatus

Calcidiscus thiersteinii
Cococliths circular to sub-circular <5µm, sutures often complex

fossil species
Calcidiscus gallagheri
Larger weakly elliptical Calcidiscus species with clearly elliptical central area, opening spanned by a perforated plate.

Calcidiscus macintyrei
Large (>10 µm) circular species of Calcidiscus with central opening.

Calcidiscus pataecus
Small to medium (~3-8µm), elliptical Calcidiscus coccoliths with a closed central area.

Calcidiscus premacintyrei
Large, weakly elliptical species of Calcidiscus, central area open, and distinctly elliptical.

Calcidiscus salomonii
Calcidiscus species with small coccoliths (3-6µm) with wide central opening (opening width > shield width)

Calcidiscus tropicus
Species of Calcidiscus producing circular coccoliths with open central-area.

Taxonomy:

Citation: Calcidiscus leptoporus group
taxonomic rank: species group

Distinguishing features:
Parent taxon (Calcidiscus): Circular or sub-circular; central area closed or with narrow opening
This taxon: Circular, sub-circular and broadly-eliptical calcidiscid coccoliths with closed central-area.

Farinacci & Howe catalog pages:

Search data:
Lith size: 3->14µm;
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Notes: Predominantly Neogene to Modern group with early forms (e.g., Calcidiscus? detectus) recorded in the Oligocene.
Last occurrence (top): Extant. Data source: Total of ranges of the species in this database
First occurrence (base): within NP23 zone (29.62-32.02Ma, base in Rupelian stage). Data source: Total of ranges of species in this database

Plot of occurrence data:

References:

Bown, P. R. & Dunkley Jones, T. (2012). Calcareous nannofossils from the Paleogene equatorial Pacific (IODP Expedition 320 Sites U1331-1334). Journal of Nannoplankton Research. 32(2): 3-51. gs O

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C. leptoporus group compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 14-9-2024

Taxon Search:
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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=168 Go to Archive.is to create a permanent copy of this page - citation notes
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Comments (5)

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Simun Ascic(Croatia)
Is there possibility that C. tropicus and C. leptoporus diverged from same species, in early Miocene? In my analyses I have over 90% of Calcidiscus, in whole preparation, with small open central area, dimensions 5-10?m. I couldn't seen grill in central. It is a Central Paratethyan, probably NN5-NN6! Best regard, Simun Ascic
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Mike Styzen(US)
Take a look at this article: Knappertsbusch, Michael, 2000; MORPHOLOGIC EVOLUTION OF THE COCCOLITHOPHORID CALCIDISCUS LEPTOPORUS FROM THE EARLY MIOCENE TO RECENT Journal of Paleontology; July 2000; v. 74; no. 4; p. 712-730
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Simun Ascic(Croatia)
Absolutely helps! I see there is a problem with taxonomy. These specimens have no grid in central area. It seems to me that central area is fully open. That means it's not C. carlae! Entire population have 5-10_m in diameter. Most of them have less than 10_m. They are represented with 90 and more percentage in slides and they are beautifully preserved, even entire coccospheres. There are still: H. carteri, Co. pelagicus, Co. miopelagicus, B. bigelowii, P. multipora, some indeterminable discoasters... I didn't found \classical example"of Calcidiscus leptoporus! This is Paratethyan and there is no sea conditions after NN6! Thank You very much!"""
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Simun Ascic(Croatia)
I'm not sure we really have a handle on Calcidiscus taxonomy. There appears to be a repeating pattern of large and small forms with more open and closed central areas. Some with the open central areas have a visible grid. For me it boils down to form taxa. If I encountered that specimen I would call it C. tropicus if it was less than 10_m, or C. macintyrei if it was over 10_m. If it had a visible grid in the central area I would call it Cycloperfolithus (probably should be just Calcidiscus) carlae regardless of size. I'm not sure of the utility of splitting C. leptoporus and C. tropicus as they probably are not real biological taxa and do not, in my work, have much stratigraphic significance. C. macintyrei which is just a size thing has a useful top up in NN 19 so I continue to distinguish them all the way through the range just to be consistent. C. carlae (I'm not sure of the biological significance of the visible grid) has a very useful top in NN16, more or less equivalent to Discoaster tamalis. I continue splitting that out for the same reason. All the forms appear to come and go throughout the range of the group. More work is needed. Does this help?
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Mike Styzen(US)
C. leptoporus/tropicus/macintyrei/carlae: My entirely utilitarian splitting of this group is a little different than above. I must never have seen assemblages young enough to include C. quadriperforatus as I have never seen a member of this group that large younger than C. macintyrei. I must admit that until very recently I never called anything C. tropicus. I did not see any practical reason to split them from C. leptoporus, so anything less than 10µm was recorded as leptoporus. Above 10µm they became C. macintyrei regardless of the openness of the central area. On the other hand, the specimens with a grill in the open central area (C. carlae) are very important to me as they lave a nice LAD in NN 16. Jeremy just calls these C. tropicus with grill... More recently I have been splitting C. tropicus/leptoporus just to make my data blend better with contractor data. As a side note I always call the small sort of dim Calcidiscus C. pataecus, just because they are easy to recognise.