Nannotax3 - ntax_cenozoic - Braarudosphaerales

Citation: Braarudosphaerales Aubry 2013

Taxonomic discussion: Recent research has demonstrated that modern Braarudosphaera produces the pentaliths extra-cellularly and that they have a very different structure to heterococcoliths, characterised by laminar sub-structure and tagential c-axis orientations (Hagino et al. 2016). So, they are clearly produced by a different biominerlaisation mode (sensu Young et al. 1999) to either holococcoliths or heterococcoliths. In parallel, molecular genetic data shows they are haptophytes closely related to coccolithophores but either occupying a basal position within the coccolithophore clade or falling just outside it (Takano et al. 2006, Hagino et al. 2013). These two lines of evidence strongly justify separating the group as a discrete order within the haptophyta.
In the Cenozoic the order only contains the one, well-established, family the Braarudosphaeraceae. However, in the Mesozoic there are other groups showing affinities to them - in particular the Nannoconids (Lees & Bown 2016).

Distinguishing features:
Parent taxon (ntax_cenozoic): Extant coccolithophores and Cenozoic calcareous nannofossils - Mesozoic nannofossils are in a separate module
This taxon: 2N(?) cell covered by pentaliths (plates formed of 5 segments with lamellar sub-structure) formed extracellualrly N: cell motile, covered by scales

Geological Range:
Last occurrence (top): Extant. Data source: Total of range of species in this database
First occurrence (base): at base of Cenomanian Stage (0% up, 100.5Ma, in Albian stage). Data source: Total of range of species in this database

References:

Aubry, M. -P. (2013). Cenozoic Coccolithophores: Braarudosphaerales. Micropaleontology Press, American Museum of Natural History, New York. 1-336. gs

Hagino, K., Onuma, R., Kawachi, M. & Horiguchi, T. (2013). Discovery of an Endosymbiotic Nitrogen-Fixing Cyanobacterium UCYN-A in Braarudosphaera bigelowii (Prymnesiophyceae). PLoS One. 8(12): 1-11. gs

Hagino, K., Tomioka, N., Young, J. R., Takano, Y., Onuma, R. & Horiguchi, T. (2016). Extracellular calcification of Braarudosphaera bigelowii deduced from electron microscopic observations of cell surface structure and elemental composition of pentaliths. Marine Micropaleontology. 125(1): 85-94. gs

Lees, J. A. & Bown, P. R. (2016). New and intriguing calcareous nannofossils from the Turonian (Upper Cretaceous) of Tanzania. Journal of Nannoplankton Research. 36(1): 83-95. gs

Takano, Y., Hagino, K., Tanaka, Y., Horiguchi, T. & Okada, H. (2006). Phylogenetic affinities of an enigmatic nannoplankton, Braarudosphaera bigelowii based on the SSU rDNA sequences. Marine Micropaleontology. 60: 145-156. gs

Young, J. R., Davis, S. A., Bown, P. R. & Mann, S. (1999). Coccolith ultrastructure and biomineralisation. Journal of Structural Biology. 126: 195-215. gs

Daughter taxa (time control age-window is: 0-800Ma)					Granddaughter taxa
				Braarudosphaeraceae Coccospheres pentagonal dodecahedra formed of five pentagonal plates	Braarudosphaera Hexadelus Micrantholithus Pemma Pentaster

Braarudosphaerales

References:

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