Nannotax3 - ntax_cenozoic - Emiliania huxleyi

Citation: Emiliania huxleyi (Lohmann 1902) Hay & Mohler, in Hay et al. 1967

Basionym: Pontosphaera huxleyi Lohmann 1902

Synonyms:

Hymenomonas huxleyi (Lohmann 1902) Kamptner 1930
Coccolithus huxleyi (Lohmann 1902) Kamptner 1943
Gephyrocapsa huxleyi (Lohmann 1902) Reinhardt 1972
Coccolithus cordus Kamptner (1967) [my identification - JRY 2015]
Coccolithus cucullus Lecal & Bernheim (1960) [my identification - JRY 2015]
Coccolithus huxleyi tenuis Kamptner (1943) [my identification - JRY 2015]
Cricolithus adriaticus Cohen (1965) [my identification - JRY 2015]
Cricolithus jonesi Cohen (1965) [my identification - JRY 2015, the TEM images are proto-coccolith rings, the LM images (holotype) are of a complete specimen. In the literature this name has been randomly misapplied to various ring-shaped coccoliths]

Taxonomic discussion: Variability of extant E. huxleyi: Young & Westbroek (1991) distinguished four types (A, B, C & corona) based on heterococcolith morphology, see also van Bleijswijk et al. (1991) and Young (1994). Medlin et al. (1996) consider these types should be regarded as separate varieties, their proposed names are noted as synonyms of the types but since the status of these morphotypes is still being actively researched, and with conflicting results, we prefer to retain the informal morphotype designations.

More recent research has both recognised more varieties and supported sub-dividing them into two sets - A Group and B Group. These two groups seem to be consistently separable using shape in profile, central area structures and degree of calcification, and there is no evidence of culture strains changing morphology from one group to the other.
Within each group numerous different varieties can be recognised, but these tend to intergrade.

Bendif et al. (2019) used whole genome sequencing to analyse relationships within the extant Noelaerhabdaceae and strongly supported separation of the type A vs type B groups.

Bendif et al (2023) propose subdivision of E. huxleyi into 3 species based on whole genome analysis of multiple species. They formally apply the name pujoseae to group B and divide group A into two species huxleyi and pseudohuxleyi. Unfortunately the two species huxleyi and pseudohuxleyi cannot be consistently separated using morphology alone, so this scheme is not applicable in practice.

Gephyroscapsa huxleyi? It has long been inferred that E. huxleyi evolved from Gephyrocapsa and this has been amply confirmed by molecular genetic studies (e.g. Bendif et al 2019, Bendif et al 2023). Given this the genus Gephyrocapsa is paraphyletic unless Emiliania is placed in it and so some biologists favour this taxonomy (e.g. Bendif et al. 2019, Filatov et al. 2021). We do not follow this on the following grounds.

The Noelaerhabdaceae are a group with a very extensive fossil record, so unless all species are placed in the same genus paraphyletic genera are inevitable (Young & Bown 1997).
Including E. huxleyi in Gephyrocapsa removes the morphological utility of Gephyrocapsa and makes it impossible to produce a definition of it which does not include all members of the Noelaerhabdaceae.
The Noelaerhabdaceae are an abundant group in the Cenozoic of great value for both biostratigraphy and paleoceanography. They are also diverse and their species-level taxonomy is difficult, hence generic level subdivision is needed for practical study and communication - so the alternative of placing all species in one genus is not desirable.
The taxon Emiliania huxleyi is very well-established (Google scholar returns >20,000 articles) which increases the undesirablility of changing the nomenclature.
There is an increasingly strong case for separating the A and B group morphotypes as separate species (E. huxleyi and E. pujosae), given this it will be important to have a simple taxonomic label (Emiliania) to cover both taxa - for instance to allow identification for routine marine biological or palaeontological work.

More generally, we would argue that taxonomy (like the Nannotax website) is a system of communication shared among a diverse community of scientists and that proposals for revising taxonomy should take into account the full range of data and of users rather than focussing exclusively on one perspective.

Distinguishing features:
Parent taxon (Emiliania): No bridge, slits between distal shield elements
This taxon: See generic diagnosis (monospecific)

Coccospheres often with multiple layers of coccoliths.
The open structure of E. huxleyi coccoliths makes them highly vulnerable to both overgrowth and etching.

Ubiquitous species, often forming blooms. Dominant neritic species in the Atlantic, but G. oceanica fills this niche in much of the Indian Ocean and Pacific.

Geological Range:
Notes: Determining the exact placement of the FAD is tricky even with SEM, but if E. huxleyi is common the age is definitely within NN21
Last occurrence (top): Extant. Data source: zonal marker, e.g Young 1998
First occurrence (base): within NN21 zone (0.00-0.29Ma, base in Ionian stage). Data source: Young 1998

References:

Bendif, E. et al. (2019). Repeated species radiations in the recent evolution of the key marine phytoplankton lineage Gephyrocapsa. Nature Communications. 10(2): 1-9. gs

Bendif, E. M. et al. (2023). Rapid diversification underlying the global dominance of a cosmopolitan phytoplankton. The ISME Journal. 17(4): 630-640. gs

Cohen, C. L. D. (1965). Coccoliths and discoasters, some aspects of their geologic use. Geologie en Mijnbouw. 55: 337-344. gs

Filatov, D. A., Bendif, E. M., Archontikis, O. A., Hagino, K. & Rickaby, R. E. M. (2021a). The mode of speciation during a recent radiation in open-ocean phytoplankton. Current Biology. 31: 1-11. gs

Hay, W. W., Mohler, H. P., Roth, P. H., Schmidt, R. R. & Boudreaux, J. E. (1967). Calcareous nannoplankton zonation of the Cenozoic of the Gulf Coast and Caribbean-Antillean area, and transoceanic correlation. Transactions of the Gulf-Coast Association of Geological Societies. 17: 428-480. gs O

Kamptner, E. (1930). Der Kalkflagellaten der Süsswaters und ihre Beziehungen zu jenen des Brackwassers und des Meeres. Internationale Revue für die gesamte Hydrobiologie und Hydrographie. 24: 147-163. gs

Kamptner, E. (1943). Zur Revision der Coccolithineen-Spezies Pontosphaera huxleyi Lohm. Anzeiger der (Kaiserlichen) Akademie der Wissenschaften, Wien. 80: 73-49. gs

Kamptner, E. (1967). Kalkflagellaten - Skelettreste aus Tiefseeschlamm des Südatlantischen Ozeans. Annalen des Naturhistorischen Museums in Wien. 71: 117-198. gs O

Lecal, J. & Bernheim, A. (1960). Microstructure du squelette de quelques Coccolithophorides. Bulletin de la Société d'Histoire Naturelle de l'Afrique du Nord. 51: 273-297. 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 O

Medlin, L. K. et al. (1996). Genetic characterization of Emiliania huxleyi (Haptophyta). Journal of Marine Systems. 9: 13-32. gs

Reinhardt, P. (1972). Coccolithen. Kalkiges Plankton seit Jahrmillionen. A. Ziemsen Verlag, . 1-99. gs

van Bleijswijk, J. et al. (1991). Distribution of two types of Emiliania huxleyi (Prymnesiophyceae) in the North East Atlantic Region as determined by immunoflourescence and electron microscopy. Journal of Phycology. 27(3): 566-570. gs

Wise, S. W. & Wind, F. H. (1977). Mesozoic and Cenozoic calcareous nannofossils recovered by DSDP Leg 36 drilling on the Falkland Plateau, south-west Atlantic sector of the Southern Ocean. Initial Reports of the Deep Sea Drilling Project. 36(269-491): -. gs O

Yang, T. -N., Wei, K. & Wu, J. -T. (2012). Marine coccolithophores around Taiwan. Biodiversity Research Center, Academica Sinica, Taipei. 1-96. gs

Young, J. R. & Bown, P. R. (1997). Higher classification of calcareous nannofossils. Journal of Nannoplankton Research. 19(1): 15-20. gs O

Young, J. R. & Westbroek, P. (1991). Genotypic variation in the coccolithophorid species Emiliania huxleyi. Marine Micropaleontology. 18: 5-23. gs

Young, J. R. (1998). Neogene. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 225-265. gs

Comments (2)

Mireille Ghoussoub(Cambodia)

I am graduate student at the University of Toronto. Myself and my supervisor, Prof. Geoffrey Ozin, are seeking to reproduce an image from the microtax.org in a book that we are publishing on the topic of CO2 chemistry and climate change.

The manuscript will be published with the University of Toronto Press, Canada's leading academic publisher. We wish to request your permission to reproduce the following image: Young_etal_2003_113-19.JPG

Any information on possible use of this content would be greatly appreciated. Thank you for your time.

3 May 2019 22:41

Jeremy Young(UK)

HI Mireille

Thanks for asking and yes that should be fine - I will email you directly.

Jeremy

6 May 2019 13:24

Sub-taxa & variants (time control age-window is: 0-800Ma)		Granddaughter taxa
	Emiliania huxleyi A group Shields sub-parallel; highly variable tube width; usually with a grill in the central area; usually robust distal shield elements (<50% of distal shield area is slits)	Emiliania huxleyi type A Emiliania huxleyi type A overcalcified Emiliania huxleyi type R Emiliania huxleyi var. corona Emiliania huxleyi type A malformed
	Emiliania huxleyi B group Distal shield curved in profile, not parallel to proximal shield, often smaller than proximal shield; tube narrow; central area open, or with plate or irregular laths; delicate distal shield elements (>50% of distal shield area is slits)	Emiliania huxleyi type B Emiliania huxleyi type B-C Emiliania huxleyi type C Emiliania huxleyi type O

Emiliania huxleyi

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