Nannotax3 - ntax_cenozoic - SY mediterranea group

arrayname: original

Nannotax3 - ntax_cenozoic - SY mediterranea group Nannotax3 - ntax_cenozoic - SY mediterranea group

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

Taxonomic 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
Zygosphaera Kamptner 1936 - type Zygosphaera hellenica Kamptner, 1937
Syracolithus Kamptner 1941 - type Syracosphaera dalmatica Kamptner 1927

The synonymy with Zygosphaera and Syracolithus is based on life-cycle associations.

Taxonomic discussion: This group corresponds to the genus Coronosphaera as previously used. As discussed by Triantaphyllou et al. (2016) and Young et al. (2020) the species S. mediterranea has proven life-cycle associations with several different holococcoliths. As a result the genus Coronosphaera Gaarder 1977 is now a junior synonym of both Zygosphaera Kamptner 1936 and Syracolithus Kamptner 1941

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

Farinacci & Howe catalog pages: Coronosphaera * , Laminolithus * , Zygosphaera + * , Syracolithus + *

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.

Distinguishing features of this set of species from other Syracosphaera species

Strong anti-clockwise imbrication of the rim elements
Absence of flanges
Absence of exothecal coccoliths
Having more radial laths than rim elements (ca. 1.5:1)

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 S. 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:

LITHS: murolith, elliptical, CA: ca_disjunct, plate, grill,
CSPH: equant, CFC, CROSS-POLARS: V-prominent, R-prominent,

Lith 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 ranges of the species in this database
First occurrence (base): within Miocene Epoch (5.33-23.03Ma, base in Aquitanian stage). Data source: Total of ranges of species in this database

Plot of occurrence data:

Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
Neptune data: this is a higher taxon page so Neptune data is not plotted. For the customisable plot option go to a genus page Parent: Syracosphaera

References:

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

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 [2015](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. S1: 1-132. gs

Young, J. R., Arapov, J., Skejic, S., Bakrac, A., Buzancic, M. & Triantaphyllou, M. (2020). Verification of the life-cycle of Helicosphaera pavimentum, and discussion of the identity of Syracolithus dalmaticus. Journal of Nannoplankton Research. 30(1): 41-47. gs