Calcidiscus sp. Specimens which cannot be assigned to established species
Taxonomy:
Citation: Calcidiscus Kamptner, 1950Rank: GenusType 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: Parent taxon (Calcidiscaceae): 2N: cells non-motile, bearing placoliths with R-unit confined to proximal shield, mostly circular. N: cells motile, holococcolith-bearing This taxon: Circular or sub-circular; central area closed or with narrow opening
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): in upper part of Thanetian Stage (62% up, 57.2Ma, in Thanetian stage). Data source: Total of range 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. See also: customisable plot Parent: Calcidiscaceae
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. gsVO
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. gsO
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). Die Nannofosilien des Badenien. 8.2 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, Badenien M-4: IGCP Project 25. 486-489. gsVO
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. gsVO
Wilcoxon, J. A. (1970a). Cyclococcolithina Wilcoxon nom. nov. (nom. subst. pro Cyclococcolithus Kamptner, 1954). Tulane Studies in Geology and Paleontology. 8: 82-83. gsVO
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. gsVO
Calcidiscus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 30-1-2023
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