SY mediterranea group


Classification: ntax_cenozoic -> Syracosphaerales -> Syracosphaeraceae -> Syracosphaera -> SY mediterranea group
Sister taxa: SY pulchra gp, SY molischii gp, SY nodosa gp, SY mediterranea group, Syraco - fossil, S. sp.

Daughter taxa (time control age-window is: 0-800Ma)
Syracosphaera mediterranea
Typical form, medium sized; BCs 3-4 µm, coccospheres 12-20 µm
Syracosphaera maxima
Like C. mediterranea but larger; BCs 4-6 µm, coccospheres 25-40 µm; CFCs more elliptical.
Syracosphaera sp. Y
Similar to S. mediterranea but wall is narrower and higher, lacking clear inner cycle and with small central spine.

Taxonomy:

Citation: SY mediterranea group Gaarder in Gaarder & Heimdal, 1977
Rank: species group
Type species: Syracosphaera mediterranea Lohmann 1902
Synonyms: Laminolithus Heimdal 1980 - the type of Laminolithus is Zygosphaera hellenica which is now known to be a life-cycle phase of Coronosphaera mediterranea
Taxonomic discussion: Coronosphaera is usually placed in the family Syracosphaeraceae, but has also been considered a genus incertae sedis within the order Syracosphaerales. It is distinguished from Syracosphaera by Triantaphyllou et al. (2106) discuss the genus at some length and argue that Coronosphaera should be regarded as a synonym of Syracosphaera. We do not follow that argument here but do agree that there is sufficent evidence for the affinity of the two genera to include Coronosphaera in the Syracosphaeraceae. [my interpretation - JRY 2018]

Distinguishing features: BCs muroliths with imbricate wall, bipartite axial structure. No XCs (formerly Coronosphaera)

Farinacci & Howe catalog pages: Coronosphaera * , Laminolithus *


Morphology: Coccospheres - Monothecate, dimorphic, motile.
Body coccoliths - flangeless muroliths; rims formed of an outer cycle of strongly imbricate (anticlockwise) elements and an inner cycle of vertical elements. Central area with plaque formed of two plates.
Circum Flagellar Coccoliths - similar but slightly smaller, with low spine.

Number of lath vs. rim elements. As noted by Gaarder & Heimdal (1977) there are more radial laths than rim elements. This is unusual as in other Syracosphaeraceae there is one lath per rim unit. Young et al. (2003) stated that there were 2 lath elements per rim elements, however, counts on several specimens indicate that typically there are 45-55 lath elements and 30-36 rim elements, ie. a ratio of 1.5:1 on modern C. mediterranea. Moreover, on Miocene fossil Coronosphaera from the Paratethys (material described by Galovic & Young 2012) there is one lath element per rim element. So although rim element number does appear to be consistently lower than lath element number in modern Coronosphaera this is not an ancestral character. [my obs. JRY 2015]

Search data:
TagsLITHS: murolith, elliptical, CA: ca_disjunct, grill, plate,
CSPH: equant, CFC, CROSS-POLARS: V-prominent, R-prominent,
MetricsLith size: 2.5->6µm; Coccosphere size: 13->53µm;
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): Extant Data source: Total of range of species in this database
First occurrence (base): at base of Aquitanian Stage (0% up, 23Ma, in Aquitanian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Gaarder, K. R. & Heimdal, B. R. (1977). A revision of the genus Syracosphaera Lohmann (Coccolithineae). “Meteor” Forschungsergebnisse, Reihe D, Biologie. 24: 54-71. gs

Galovic, I. & Young, J. R. (2012). Revised taxonomy of some Middle Miocene calcareous nannofossils in the Paratethys. Micropaleontology. 58(4): -. gs

Triantaphyllou, M. et al. (2016). Coccolithophore combination coccospheres from the NE Mediterranean Sea: new evidence and taxonomic revisions. Micropaleontology. 61(6): 457-472. gs

Young, J. R., Geisen, M., Cros, L., Kleijne, A., Probert, I. & Ostergaard, J. B. (2003). A guide to extant coccolithophore taxonomy. Journal of Nannoplankton Research, Special Issue. 1: 1-132. gs V O


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SY mediterranea group compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 18-5-2021

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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=361 Go to Archive.is to create a permanent copy of this page - citation notes



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