Nannotax3 - ntax_cenozoic

Citation: Coccolithales Schwarz, 1932

Taxonomic discussion: The Family Coccolithaceae has often been used for all placoliths not placed in the Noelaerhabdaceae (e.g. Jordan & Kleijne 1994; Jordan & Green 1994). Young & Bown (1997) noted that two major structural types occurred in this group and divided it into two families, the Coccolithaceae and Calcidiscaceae, which they then included in their revised order Coccosphaerales. Following Jordan et al. (2004), the correct name for this order is Coccolithales. The Family Pleurochrysidaceae was also tentatively included in this order on the grounds of coccolith structure. This grouping has subsequently been supported by molecular genetic studies (Edvardsen et al. 2000; Fujiwara et al. 2001; Sáez et al. 2003, 2004) and further studies of the structure of Pleurochrysis coccoliths (Marsh 1999). In addition, the Hymenomonadaceae were included by Young et al. (2003), since numerous cytological and life-cycle characters indicate that they are closely related to the Pleurochrysidaceae (e.g. Gayral & Fresnel 1971; Gayral & Fresnel 1983; Fresnel & Billard 1991; Fresnel & Probert subm.), even though their coccolith structure is not obviously similar. This placement is also supported by molecular genetics (Sáez et al. 2004).

Distinguishing features:
Parent taxon (ntax_cenozoic): Extant coccolithophores and Cenozoic calcareous nannofossils - Mesozoic nannofossils are in a separate module
This taxon: 2N: Mostly placolith heterococcoliths with V-unit forming the distal shield; R-unit the proximal shield. Non-motile
N: Form holococcoliths formed of single block, or non-calcifying

Coccoliths: The Coccolithaceae, Calcidiscaceae and Pleurochrysidaceae all form placolith coccoliths, i.e. coccoliths formed of two shields separated by a tube. Common structural features are:
1. Growth occurs downward as well as upward from the proto-coccolith ring, which consequently becomes embedded within the rim. Hence, on intact specimens, there is no obvious belt of alternating V- and R-elements, but such a belt is seen on specimens where the proximal shield has been partially detached (Young et al. 2004).
2. The V-units form the distal shield and most of the tube whilst the R-units form the proximal shield and in some cases part of the tube. In consequence the distal shield is dark in cross-polarised light whilst the proximal shield is bright.
Coccospheres: Monomorphic, this applies even to the motile genera of the Pleurochrysidaceae and Hymenomonadaceae, and to the known holococcolith stages of the Coccolithaceae and Calcidiscaceae.

Heteromorphic life-cycles have been documented from culture studies of all four families (Parke & Adams 1960; Rowson et al. 1986; Fresnel & Billard 1991; Kleijne 1991; Fresnel 1994; Cortes 2000; Renaud & Klaas 2001; Geisen et al. 2002; Billard & Inouye 2004; Houdan et al. 2004). In the Coccolithaceae and Calcidiscaceae, non-motile diploid heterococcolith-bearing stages alternate with motile haploid holococcolith-bearing stages. In the Pleurochrysidaceae and Hymenomonadaceae, motile diploid heterococcolith-bearing stages alternate with motile and benthic haploid non-calcifying stages.

Geological Range:
Last occurrence (top): Extant. Data source: Total of ranges of the species in this database
First occurrence (base): within NP1 zone (65.47-66.04Ma, base in Danian stage). Data source: Total of ranges of species in this database

References:

Billard, C. & Inouye, I. (2004). What's new in coccolithophore biology ? In, Thierstein, H. R. & Young, J. R. (eds) Coccolithophores - From molecular processes to global impact. Springer, Berlin 1-30. gs

Cortés, M. Y. (2000). Further evidence for the heterococcolith-holococcolith combination Calcidiscus leptoporus-Crystallolithus rigidus. In, Young, J. R., Thierstein, H. R. & Winter, A. (eds) Nannoplankton ecology and palaeocology, Proceedings of the INA7 conference, Puerto Rico, February 1998. Marine Micropaleontology . 39(1-4): 35-37. gs

Edvardsen, B., Eikrem, W., Green, J. C., Andersen, R. A., Moon-Van Der Staay, S. Y. & Medlin, L. K. (2000). Phylogenetic reconstructions of the Haptophyta inferred from 18S ribosomal DNA sequences and available morphological data. Phycologia. 39: 19-35. gs

Fresnel, J. & Billard, C. (1991). Pleurochrysis placolithoides sp. nov. (Prymnesiophiceae), a new marine coccolithophorid with remarks on the status of cricolith-bearing species. British Phycological Journal. 26: 67-80. gs

Fresnel, J. & Probert, I. (2005). The ultrastructure and life cycle of the coastal coccolithophorid Ochrosphaera neapolitana (Prymnesiophyceae). European Journal of Phycology. 40(1): 105-122. gs

Fresnel, J. (1994). A heteromorphic life cycle in two coastal coccolithophorids, Hymenomonas lacuna and Hymenomonas coronata (Prymnesiophyceae). Canadian Journal of Botany. 72: 1455-1462. gs

Fujiwara, S., Tsuzuki, M., Kawachi, M., Minaka, N. & Inouye, I. (2001). Molecular phylogeny of the haptophyta based on the rbcL gene and sequence variation in the spacer region of the RUBISCO operon. Journal of Phycology. 37: 121-129. gs

Gayral, P. & Fresnel, J. (1983b). Description, sexualité et cycle de développment d'une nouvelle coccolithophoracée (Prymnesiophyceae): Pleurochrysis pseudoroscoffensis sp. nov. Protistologica. 19(2): 245-261. gs

Gayral, P. & Fresnel-Morange, J. (1971). Resultats preliminaires sur la structure et la biologie de la coccolithacee Ochrosphaera neapolitana Schussnig. Comptes rendus hebdomaire de l'Académie des sciences, Paris. 273: 1683-1686. gs

Geisen, M., Billard, C., Broerse, A. T. C., Cros, L., Probert, I. & Young, J. R. (2002a). Life-cycle associations involving pairs of holococcolithophorid species: intraspecific variation or cryptic speciation? European Journal of Phycology. 37: 531-550. gs

Houdan, A. et al. (2004a). Flow cytometric analysis of relative ploidy levels in holococcolithophore-heterococcolithophore (Haptophyta) life cycles. Systematics and Biodiversity. 1(4): 453-465. gs

Jordan, R. W. & Green, J. C. (1994). A check-list of the extant haptophyta of the world. Journal of the Marine Biological Association of the United Kingdom. 74: 149-174. gs

Jordan, R. W. & Kleijne, A. (1994). A classification system for living coccolithophores. In, Winter, A. & Siesser, W. G. (eds) Coccolithophores. Cambridge University Press, Cambridge 83-105. gs

Jordan, R. W., Cros, L. & Young, J. R. (2004). A revised classification scheme for living Haptophytes. Micropaleontology. 50(supplement 1): 55-79. gs

Kleijne, A. (1991). Holococcolithophorids from the Indian Ocean, Red Sea, Mediterranean Sea and North Atlantic Ocean. Marine Micropaleontology. 17: 1-76. gs

Marsh, M. E. (1999). Coccolith crystals of Pleurochrysis carterae: Crystallographic faces, organisation and development. Protoplasma. 207: 54-66. gs

Parke, M. & Adams, I. (1960). The motile (Crystallolithus hyalinus Gaarder & Markali) and non-motile phases in the life history of Coccolithus pelagicus (Wallich) Schiller. Journal of the Marine Biological Association of the United Kingdom. 39: 263-274. gs

Renaud, S. & Klaas, C. (2001). Seasonal variations in the morphology of the coccolithophore Calcidiscus leptoporus off Bermuda (N. Atlantic). Journal of Plankton Research. 23(8): 779-795. gs

Rowson, J. D., Leadbeater, B. S. C. & Green, J. C. (1986). Calcium carbonate deposition in the motile (Crystallolithus) phase of Coccolithus pelagicus (Prymnesiophyceae). British Phycological Journal. 21: 359-370. gs

Sáez, A. G., Probert, I., Geisen, M., Quinn, P., Young, J. R. & Medlin, L. K. (2003). Pseudo-cryptic speciation in coccolithophores. Proceedings of the National Academy of Sciences, USA. 100(12): 7163-7168. gs

Sáez, A. G., Probert, I., Young, J. R., Edvardsen, B., Wenche, E. & Medlin, L. K. (2004). A review of the phylogeny of the Haptophyta. In, Thierstein, H. R. & Young, J. R. (eds) Coccolithophores - from molecular processes to global impact. Springer, Berlin 251-270. gs

Schwarz, E. (1932). Beiträge zur Entwicklungsgeschichte der Protophyten. IX. Der Formwechsel von Ochrosphaera neapolitana.. Archiv für Protistenkunde. 77: 434-462. gs

Young, J. R. & Bown, P. R. (1997). Cenozoic calcareous nannoplankton classification. Journal of Nannoplankton Research. 19(1): 36-47. 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., Henriksen, K. & Probert, I. (2004b). Structure and morphogenesis of the coccoliths of the CODENET species. In, Thierstein, H. R. & Young, J. R. (eds) Coccolithophores - From molecular processes to global impact. Springer, Berlin 191-216. gs O

Daughter taxa (time control age-window is: 0-800Ma)		Granddaughter taxa
	Oceanic
	Coccolithaceae 2N: cells non-motile, bearing placoliths with R-unit extending from proximal shield to form upper/inner tube-cyle, mostly elliptical N: cells motile, holococcolith-bearing	Coccolithus Coronocyclus Ericsonia Solidopons Cruciplacolithus Pletolithus Campylosphaera Bramletteius Chiasmolithus Birkelundia Clausicoccus Hughesius Craticullithus Jeremyella Kilwalithus
	Calcidiscaceae 2N: cells non-motile, bearing placoliths with R-unit confined to proximal shield, mostly circular. N: cells motile, holococcolith-bearing	Calcidiscus Hayaster Oolithotus Umbilicosphaera Cryptococcolithus Hayella
	Neritic, small
	Hymenomonadaceae 2N: cells motile, bearing muroliths with open central-area; proximal and distal flanges variably developed. Coccosphere large, monomorphic with many small coccoliths. Neritic. N: non-calcifying.	Hymenomonas Jomonlithus Ochrosphaera
	Pleurochrysidaceae 2N: cells motile, bearing narrow-rimmed placoliths, with obviously interlocking V and R units, open central areas. Neritic. N: non-calcifying.	Chrysotila

Coccolithales

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