Nannotax3 - ntax_mesozoic - Cyclagelosphaera shenleyensis <title>Nannotax3 - ntax_mesozoic - Cyclagelosphaera shenleyensis

Cyclagelosphaera shenleyensis


Classification: ntax_mesozoic -> Watznaueriales -> Watznaueriaceae -> Cyclagelosphaera -> Cyclagelosphaera shenleyensis
Sister taxa: C. margerelii ⟩⟨ C. alta, C. reinhardtii, C. rotaclypeata, C. shenleyensis ⟩⟨ C. argoensis, C. jiangii, C. lacuna, C. wiedmannii ⟩⟨ C. brezae, C. centrumelliptica, C. deflandrei, C. platyaspis, C. sp.

Distinguishing features:
Parent taxon (Cyclagelosphaera): Circular watznaueriacean coccoliths.
This taxon: Cyclagelosphaera with narrow distal shield and broad, elevated, mid-tube cycle.


Taxonomy:

Citation: Cyclagelosphaera shenleyensis Black 1973
Rank: Species
Taxonomic discussion: The holotype was a drawing of a TEM and the only published image was highly ambiguous. The description of Black (1973), however, is detailed and is an excellent match for the coccosphere specimens illustrated by Jeremiah (1996) and here (JRYSEM-285-12).

Farinacci & Howe catalog pages: C. shenleyensis *

Distinguishing features:
Parent taxon (Cyclagelosphaera): Circular watznaueriacean coccoliths.
This taxon: Cyclagelosphaera with narrow distal shield and broad, elevated, mid-tube cycle.


Morphology:

This species has a very well-developed V-unit cycle so the appearance in LM should be distinctive, see also LM of Bown et al. (2011).

Extended description of Black (1973)
The petaloid rim of the distal shield is narrower than in most species of Cyclagelosphaera, and a large proportion of the distal surface is occupied by the corona [i.e the mid-tube cycle], which is unusually large. It consists of radial elements of rather variable width and shape, sometimes showing a left-handed imbrication. At the centre is a conical depression about 1 µm in diameter, solid at the bottom. In some specimens the pit and a large part of the corona are hidden beneath an irregular pile of well-crystallized rhombohedra; in others a similar overgrowth obscures the whole of these central structures.

Size:


Ecology & Biogeography


Biology & life-cycles

Phylogenetic relations

Search data:
LITHS: placolith, circular, CA: ca_conjunct, closed,
CSPH: equant, monomorphic, CROSS-POLARS: rim-unicyclic, R-prominent,
Lith size: 5->8µm;
Data source notes: original description & illustrated specimens
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Notes: Very rare in the Gault of Folkestone
Last occurrence (top): within Middle Albian Substage (107.59-110.22Ma, top in Albian stage). Data source: Black 1973
First occurrence (base): within Early Albian Substage (110.22-112.95Ma, base in Albian stage). Data source: Black 1973

Plot of occurrence data:

References:

Black, M. (1973). British Lower Cretaceous Coccoliths. I-Gault Clay (Part 2). Palaeontographical Society Monograph. 127: 49-112. gs

Bown, P. R. (2001). Calcareous nannofossils of the Gault, Upper Greensand and Glauconitic Marl (Middle Albian-Lower Cenomanian) from the BGS Selborne boreholes, Hampshire. Proceedings of the Geologists' Association. 112: 223-236. gs

Jeremiah, J. (1996). A proposed Albian to Lower Cenomanian nannofossil biozonation for England and the North Sea Basin. Journal of Micropalaeontology. 15(97-129): -. gs V O

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Cyclagelosphaera shenleyensis compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 30-1-2023

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