Taxonomy:
Distinguishing features: Solid, disk-shaped coccolith with several irregular deep depressions; formed of single block of crystalites with sub-vertical c-axes; no outer wall/tube; one or two irregular knobs on long axis.
Farinacci & Howe catalog pages: P. japonica HOL [no catalog entry yet]
Morphology: Resembles Helicosphaera carteri HOL perforate type (aka Syracolithus confusus) but crystallites are arranged in hexagonal array with c-axes vertical (so dark in plan view in cross-polars). Also larger, depressions less regular, and has one or two irregular central bosses rather than a single pyramidal boss.
Also resembles Scyphosphaera apsteinii HOL (aka Syracolithus schilleri) but lacks outer tube cycle with radial c-axes and is formed of a single mass of crystallites with depressions rather than having clearly-developed septae.
Biology & life-cycles: Several good combination coccospheres with Pontosphaera japonica HET recorded by Frada et al. 2009 in SEM and LM, from a single sample collected in the Tyrhennian Sea (Westerm Mediterranean).
See also: Pontosphaera japonica ;
Search data:Tags | LITHS: holococcolith, elliptical, CA: pores, CSPH: equant, monomorphic, CROSS-POLARS: V-prominent, |
Metrics | Lith size: 3.5->4µm; Coccosphere size: 9->12µm; Data source notes: lith size from Frada et al. 2009; csph size from illustrated specs |
Geological Range:
Last occurrence (top): Extant Data source: present in the plankton (Young et al. 2003)
First occurrence (base): within No known fossil record modern (0.00-0.00Ma, base in "Holocene" stage). Data source: [JRY rough estimate]
Plot of occurrence data:
Frada, M., Percopo, I., Young, J. R., Zingone, A., de Vargas, C. & Probert, I. (2009). First observations of heterococcolithophore-holococcolithophore life cycle combinations in the family Pontosphaeraceae (Calcihaptophycideae, Haptophyta). Marine Micropaleontology. 71(1): 20-27. gsReferences:
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Pontosphaera japonica HOL compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 21-4-2021
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