Nannotax3 - ntax_cenozoic

Citation: Calcidiscus Kamptner, 1950

Type species: Calcidiscus quadriforatus Kamptner 1950 (subj. j. syn. of C. leptoporus).

Synonyms:

Cyclococcolithus Kamptner, 1954;
Tiarolithus Kamptner 1958 (based on an isolated distal shield of Calcidiscus)
Cyclococcolithina Wilcoxon, 1970;
Striatococcolithus Bukry, 1971 (type S. pacificanus is now included in Calcidiscus)

Variants:

Cycloperfolithus Lehotayova and Priewalder, 1978 - with fine grill in central-area, and bicyclic proximal shield.

Taxonomic discussion: Species-level taxonomy:
Calcidiscus is common throughout the Neogene and shows significant variaton in size, number of elements, opening of central area, and structural details. Species concepts have been extensively discussed, most notably by Knappertsbusch (2000). Recent research has lead to a three-fold divsion of the extant Calcidiscus population, see e.g. Quinn et al. (2004), Young et al. (2003):

C. quadriperforatus; large, 7-10µm, with zone of obscured sutures around the central area. Haploid phase produces septate holococcoliths (formerly classified as Syracolithus quadriperforatus)
C. leptoporus - intermediate; 5-8µm, with continuous sutures. Haploid phase produces planar holococcoliths (formerly classified as Crystallolithus rigidus)
C. leptoporus - small; 3-5µm, with kinked sutures. Haploid phase not known.

By comparison Pliocene Calcidiscus assemblages are usually classified into:

C. leptoporus; 3-8µm circular to sub-circular with closed central area
C. tropicus & C .macintyrei; 5-11µm circular with open central area.

It is not sure how these species relate to the extant species but the degree of variation shown in fossil assemblages suggests that many more speces could probably be recognised.

Distinguishing features: Circular or sub-circular; central area closed or with narrow opening

Morphology: Coccoliths circular to sub-circular. Proximal shield, birefringent, distal shield non-birefringent with curved sutures. Shields easily separated.

Geological Range:
Last occurrence (top): Extant Data source: Total of range of species in this database
First occurrence (base): in upper part of Thanetian Stage (62% up, 57.2Ma, in Thanetian stage). Data source: Total of range of species in this database

References:

Bown, P. R., Dunkley-Jones, T. & Young, J. R. (2007). Umbilicosphaera jordanii Bown 2005 from the Paleogene of Tanzania: confirmation of generic assignment and a Paleocene origination for the family Calcidiscaceae. Journal of Nannoplankton Research. 29(1): 25-30. gs V O

Kamptner, E. (1950). Über den submikroskopischen Aufbau der Coccolithen. Anzeiger der Österreichische Akademie der Wissenschaften, Mathematische-Naturwissenschafliche Klasse, Wien. 87: 152-158. gs

Kamptner, E. (1954). Untersuchungen über den Feinbau der Coccolithen. Archiv für Protistenkunde. 100: 1-90. gs

Kamptner, E. (1963). Coccolithineen-Skelettreste aus Tiefseeablagerungen des Pazifischen Ozeans. Annalen des Naturhistorischen Museums in Wien. 66: 139-204. gs V O

Knappertsbusch, M. (2000). Morphological evolution of the coccolithophorid Calcidiscus leptoporus from the Early Miocene to recent. Journal of Paleontology. 74(4): 712-730. gs

Lehotayova, R. & Priewalder, H. (1978). Cycloperfolithus, eine neue Nannofossil-Gattung aus dem Badenien der Zentralen Paratethys. In, Papp, A., Cicha, I., Senes, J. & et al. (eds) Chronostratigraphie und Neostratotypen -Miozan N, BadenieM-4: IGCP Proj. 25. 486-489. gs

Quinn, P., Sáez, A. G., Baumann, K. -H., Steel, B. A., Sprengel, C. & Medlin, L. K. (2004). Coccolithophorid biodiversity: Evidence from the cosmopolitan species Calcidiscus leptoporus. In, Theirstein, H. R. & Young J. R. (eds) Coccolithophores - From molecular processes to global impact. Springer, Berlin 299-326. gs V O

Wilcoxon, J. A. (1970a). Cyclococcolithina Wilcoxon nom. nov. (nom. subst. pro Cyclococcolithus Kamptner, 1954). Tulane Studies in Geology and Paleontology. 8: 82-83. 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

Daughter taxa (time control age-window is: 0-800Ma)		Granddaughter taxa
	C. leptoporus group Circular, sub-circular and broadly-eliptical calcidiscid coccoliths with closed central-area.	C. gallagheri C. leptoporus C. macintyrei C. pataecus C. premacintyrei C. salomonii C. tropicus
	C. pacificanus group Medium-sized Eocene calcidiscid coccoliths with narrow or closed central-area.	C. bicircus C. gerrardii C. pacificanus C. parvicrucis C. parvus C. scullyae C. kamikurii
	Calcidiscus sp. Specimens which cannot be assigned to established species

Tags	LITHS: placolith, circular, CA: closed, CSPH: equant, monomorphic, CROSS-POLARS: rim-unicyclic, V-prominent, R-prominent,
Metrics	Lith size: 3->14µm; Data source notes: RCC

Calcidiscus

References:

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