Syracosphaera


Classification: ntax_cenozoic -> Syracosphaerales -> Syracosphaeraceae -> Syracosphaera
Sister taxa: Syracosphaera, Calciopappus, Michaelsarsia, Ophiaster

Daughter taxa (time control age-window is: 0-800Ma)Granddaughter taxa
SY pulchra gp
BCs - with distal, mid-wall and basal flanges (except S. noroitica type), and/or with low spines (except S. pulchra and S. dilatata type).
XCs - dome-shaped or muroliths.
CFCs - usually spine-bearing with bifurcate spine-tip.

SY molischii gp
BCs placolith-like (i.e. with proximal and distal flanges), often with ridges and irregular central area calcification, no spines. XCs variable.

SY nodosa gp
BCs muroliths, without distinct inner wall cycle; laths rather broad. XCs planoliths.

SY mediterranea group
BCs muroliths with imbricate wall, bipartite axial structure. No XCs (formerly Coronosphaera)

Syraco - fossil
FossilSyracosphaera coccoliths

Syracosphaera sp.
Specimens which cannot be assigned to established species

Taxonomy:

Citation: Syracosphaera Lohmann, 1902
Rank: Genus
Type species: Syracosphaera pulchra Lohmann, 1902
Synonyms: NB Caneosphaera and Deutschlandia are usually considered synonyms of Syracosphaera following Jordan & Young (1990). Gaarderia was recombined in Syracosphaera by Young et al. (2003) on the grounds that it showed too few unique features to be regarded as a separate genus.
Taxonomic discussion: Syracosphaera is a large genus and there are some clear sub-groups within it as reflected in the table above, which follows the work of Cros (2000), Young et al. (2003) and Kleijne & Cros (2009). Nonetheless, there are several reasons for keeping it as a single genus.
  1. To date molecular genetic data is only available for S. pulchra, but much more data will almost certainly appear in the medium term. This will lead to considerable reassessment of taxonomy within the Syracosphaeraceae.
  2. Life cycle combinations are to date only known for a small subset of Syracosphaera species and each additional life-cycle combination will have potential taxonomic consequences. These will be much more complex if multiple genera are used. 
  3. When using light microscopy it is often only possible to identify Syracosphaera specimens to generic level. Likewise in the fossil record isolated body coccoliths are very dificult to assign to even the larger groupings of Syracosphaera species.
So, in the interest of practical taxonomy, and to avoid nomenclatural instability, we strongly reccommend that nomenclatural changes are not made at least until there is a significant body of reliable molecular genetic and life-cycle data.
In this context, Aubry (2009) recombined many species into Deutschlandia on the basis of putative similarities of exothecal coccolith form. This reclassification is not followed here. Nonetheless, it should be noted that the combinations proposed are valid and would need to be heeded in any other reclassification of the genus.

Distinguishing features: Coccospheres usually dithecate. Exothecal coccoliths (XCs) highly variable. Endothecal coccoliths are muroliths with 1, 2 or 3 flanges, the forms with 2 flanges are often placolith-like.

Farinacci & Howe catalog pages: Syracosphaera + * , Caneosphaera * , Deutschlandia * , Gaarderia [no catalog entry yet], Heimiella * , Syracorhabdus, Periphyllophora * , Anthosphaera + *


Morphology: Coccospheres usually dithecate, Exothecal coccoliths (XCs) highly variable. Endothecal coccoliths are muroliths with 1, 2 or 3 flanges, (the forms with 2 flanges are often placolith-like), these are often differentiated into body coccoliths (BCs), circum-flagellar coccoliths (CFCs) and antapical coccoliths (AACs).
Exothecal coccolith structure: As argued by Inouye & Pienaar (1988), Cros (2000) and Young et al. (2004), exothecal coccoliths appear to be modified versions of the endothecal coccoliths, and are composed of the same set of components - rim, radial lath cycle and axial structure. However, the morphology of the coccoliths is highly variable and often radically different to that of the body coccoliths.


Biology & life-cycles: Several species are known to have holococcolith stages - including S. pulchra, S. anthos, S. bannockii, S.histrica and S. halldali.

Search data:
TagsLITHS:
MetricsLith size: 1->8µm; Coccosphere size: 3->70µm;
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Notes: About 60 modern species of Syracosphaera are known (Young et al. 2003) and their coccolith morphology is well established (see examples above). Most Pleistocene specimens of Syracosphaera can be assigned to modern taxa, e.g. S. pulchra and S. lamina. However, in older sediments the occasional Syracosphaera specimens often appear to belong to different species.
Last occurrence (top): Extant Data source: Total of range of species in this database
First occurrence (base): in lower part of Danian Stage (28% up, 64.8Ma, in Danian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Aubry, M. -P. (2009). A sea of Lilliputians. Palaeogeography Palaeoclimatology Palaeoecology. 284: 88-113. gs

Cros, L. (2000). Variety of exothecal coccoliths of Syracosphaera. Journal of Nannoplankton Research. 22(1): 41-51. gs V O

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

Kleijne, A. & Cros, L. (2009). Ten new extant species of the coccolithophore Syracosphaera and a revised classification scheme for the genus. Micropaleontology. 55(5): 425-462. gs

Kleijne, A. (1993b). Morphology, Taxonomy and distribution of extant coccolithophorids (Calcareous nannoplankton). Drukkerij FEBO B.V., Katwijk. 1-321. gs

Loeblich, A. R. & Tappan, H. (1966). Annotated index and bibliography of the calcareous nannoplankton. Phycologia. 5: 81-216. gs

Lohmann, H. (1902). Die Coccolithophoridae, eine Monographie der Coccolithen bildenden Flagellaten, zugleich ein Beitrag zur Kenntnis des Mittelmeerauftriebs. Archiv für Protistenkunde. 1: 89-165. gs V O

Lohmann, H. (1912). Untersuchungen über das Pflanzen- und Tierleben der Hochsee, zugleich ein Bericht über die biologischen Arbeiten auf der Fahrt der "Deutschland" von Bremerhaven nach Buenos-Aires in der Zeit vom 7. Mai bis 7. September 1911. Veröffentlichungen des Instituts für Meereskunde an der Universität Berlin, Neue Folge. A. Geographisch-naturwissenschaftliche Reihe. 1: 1-92. gs V O

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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Syracosphaera compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 14-5-2021

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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=1339 Go to Archive.is to create a permanent copy of this page - citation notes



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