Pontosphaera


Classification: Coccolithophores -> Zygodiscales -> Pontosphaeraceae -> Pontosphaera
Sister taxa: Pontosphaera, Scyphosphaera,

Daughter taxa: (blue => in age window 0-800Ma)
Numerous medium to large pores
Rim elevated, 3 or more cycles of large (0.3-0.5 µm) pores.
Rim elevated, 3 or more cycles of pores.
Large thick coccolith (orange birefringence in XPL) with broad thickened rim/margin and a relatively thick narrow perforate central plate.
Pontosphaera with central field of irregularly arranged, variable size, pores.
Marginal cycle of small medium pores and small pores across plate
Pores elongate and in pairs
Pontosphaera with central rea protruding above rim, marginal cycle of elongates pores and more irregular central part.
Very large (16-19 µm), large pores around margin, and a few irregular pores in centre
Small to medium-sized; rim narrow; central area wide, spanned by a finely perforate plate
Flaring rim, small perforations or solid plate
Rim strongly elevated, narrow, flaring; central-area occupied by thin plate with numerous small pores.
Pontosphaera with elevated, birefringent rim and a thin, low birefringence plate with many small perforations.
Pontosphaera with elevated, birefringent rim and a thin, low birefringence plate without perforations.
Simple unadorned plate, typically with two longitudinal slits, and a broad raised margin/rim.
Large Pontosphaera with flaring rim, central area filled by coarse radial crystals
Large Pontosphaera with elevated rim, and single large central opening
Pontosphaera with flaring rim, central area with two large openings [my interpretation - JRY 2017]
Distal flange, one or two large openings
Large (9-17 µm) Pontosphaera with high flaring rim and distal flange that displays discernible elements in light microscope. The plate is thin and indistinct in XPL, typically with large central hole.
Large (9-10 µm) Pontosphaera with elevated rim and distal flange; sculpted margin and large central opening.
Similar to P. formosa but with two large holes in plate separated by a transverse bar.
Very large, elliptical with broad, high rim and narrow central opening.
Very large, broadly elliptical with broad, low rim and narrow to closed central opening.
Large, narrowly elliptical, lens-shaped pontosphaerid with high rim and apparently vacant central area.
Flat plate, pores very small or absent
Rim flush with central-area pores very small (<0.1µm) often infilled during diagenesis.
Simple unadorned plate, typically with two narrow longitudinal slits; margin narrow or inconspicuous.
Simple unadorned plate with a large central hole; the rim is narrow and not distinct from the plate in XPL.
Sculpted surface, +/- two central pores
Pontosphaera with plate scalloped towards its outer edge and pierced by two longitudinal slits or small holes.
Elliptical pontosphaerid with central area plate crossed by prominent oblique ridges that are bright in cross-polarised light.
Pontosphaera with plate that has marginal furrows and small pores, and larger pores towards the centre.
Pontosphaera with plate that has oblique marginal furrows and oblique pores, and larger pores towards the centre; there may be two central longitudinal slits; rim narrow.
Large elliptical Pontosphaera with small pores and two central longitudinal holes separated by conjunct bar. The plate thickens towards the edge but the rim is difficult to distinguish in XPL.
Pontosphaera with a row of small "pores" towards outer edge of plate and a large central opening spanned by an oblique tranverse bar. The "pores" appear as dark spots in LM and so look like openings, but in EMs it is clear they are depressions on the distal surface and do not extend to the proximal surface.
Pontosphaera with plate scalloped towards its outer edge and pierced by two holes, defining a transverse bar. The scalloping is defined by narrow radial ridges and furrows, which run inwards towards the centre.
Small Pontosphaera with proximal grill and narrow transverse bar, usually with a distinct kink.
smooth surface + two central pores
Simple unadorned plate with two closely spaced, longitudinally arranged holes; the rim/margin is usually distinct from the plate in XPL, but not high.
Simple unadorned plate with two widely spaced longitudinally arranged holes; the rim is usually distinct from the plate in XPL, and can be relatively high.
Simple unadorned plate with two large holes that define a transverse bar; the rim is narrow and not distinct in XPL. Hole size, and thus bar width, varies greatly. The bar is typically transverse but may be slightly oblique.
Similar to P. exilis but with prominent nodes at the ends of the bar
distinctly oblique bar
Elongate Pontosphaera with distinctly oblique disjunct bar and elongate openings
Elongate Pontosphaera with strongly oblique bar and very restricted openings
unidentified
Specimens which cannot be assigned to established species

Taxonomy:

Citation: Pontosphaera Lohmann, 1902
Rank: Genus
Type species: Pontosphaera syracusana Lohmann, 1902
Variants:
Synonyms:
Notes & discussion: Species level taxonomy is poorly worked out, particularly in the Neogene.

Distinguishing features: Coccoliths are muroliths, central area with variable number of perforations. V-units form narrow imbricate outer wall, R-units form inner wall and central-area.

Farinacci & Howe catalog pages: Pontosphaera * , Crassapontosphaera * , Discolithina * , Discolithus + * , Koczyia * , Nothodiscus * , Transversopontis *

Search data:
TagsLITHS: murolith, elliptical, RIM: outer wall acw-imbricate, CA: pores,
CSPH: spherical, equant, monomorphic, V-UNITS: outer-rim, V-prominent, R-UNITS: c-str, inner-rim, px-plate, R-prominent, DETAILS: isogyres oblique, isogyres separated,
MetricsLith size: 5->22µm;
Sources:
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 Selandian Stage (4% up, 61.5Ma, in Selandian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Boudreaux, J. E. & Hay, W. W. (1969). Calcareous nannoplankton and biostratigraphy of the late Pliocene-Pleistocene-Recent sediments in the Submarex cores. Revista Española de Micropaleontología. 1(3): 249-292. gs :: ::

Huxley, T. H. (1868). On some organisms living at great depths in the North Atlantic Ocean. Quarterly Journal of Microscopical Science. 8: 203-212. gs :: ::

Loeblich, A. R. & Tappan, H. (1963). Type fixation and validation of certain calcareous nannoplankton genera. Proceedings of the Biological Society of Washington. 76: 191-198. 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 :: ::

Stradner, H., Aubry, M. -P. & Bonnemaison, M. (2010). Calcareous nannofossil type specimens in the collection of the Geological Survey of Austria: A taxonomic and stratigraphic update. Jahrbuch der Geologischen Bundesanstalt. 150(1-2): 9-84. gs :: ::


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Pontosphaera compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 5-6-2020

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Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=1063 Go to Archive.is to create a permanent copy of this page - citation notes



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