Braarudosphaera bigelowii


Classification: Coccolithophores -> Braarudosphaerales -> Braarudosphaeraceae -> Braarudosphaera -> Braarudosphaera bigelowii
Sister taxa: B. bigelowii, B. insecta, B. magnei, B. pentagonica, B. perampla, B. perversus, B. sequela, B. stylifera, B. sp.,

Distinguishing features: Pentaliths pentagonal with sraight edges and flat top surface


Taxonomy:

Citation: Braarudosphaera bigelowii (Gran & Braarud 1935) Deflandre, 1947
Rank: Species
Basionym: Pontosphaera bigelowii Gran & Braarud 1935
Variants: Hagino et al. (2009) showed that four different size clases of Braarudosphaera bigelowii could be recognised in modern populations from around Japan and five genotypes (based on single cell PCR amplification) NB Sizes quoted are side lengths of pentaliths to convert to lith diameter multiply by 1.5 to convert to coccosphere diameter mutliply by 3. Genotypes I & II and IV & V formed clusters supporting the morphological separation. The degree of separation between the genotype groups suggested that the morphotypes were well-diverged species. No consistent differences between the forms were seen apart from size.

Possible preservational variants
Braarudosphaera rosa Levin & Joerger 1967 - lobate periphery, looks like poorly preserved B. bigelowii [my interpretation - JRY 2016]
Braarudosphaera irregularis Bybell & Gartner 1972 - irregular periphery, looks like poorly preserved B. bigelowii [my interpretation - JRY 2016]
Braarudosphaera cheloma Bybell & Gartner 1972 - notches at the end of sutures, may be a distinct species or a preservation form, described from M. Eocene [my interpretation - JRY 2016]
Micrantholithus concinnus Bramlette & Sullivan 1961 - segments extended along one edge to give rotated flower-like appearance. Looks distinctive but does not seem to have been recorded since original description so may be a preservational form. [my interpretation - JRY 2016]
Synonyms:

Farinacci & Howe catalog pages: Braarudosphaera bigelowi * Braarudosphaera cheloma * Braarudosphaera deflandrei * Braarudosphaera deflandrei maroccana * Braarudosphaera irregularis * Braarudosphaera rosa * Eodiscoaster danicus * Micrantholithus concinnus * Pontosphaera bigelowi * Pontosphaera bigelowii [no catalog entry yet]

Distinguishing features: Pentaliths pentagonal with sraight edges and flat top surface


Morphology remarks: Coccosphere are regular pentagonal dodecahedra with the plates closely butting to form a continuous cover. Liths pentagonal, surface smooth, flat or gently concave. Sutures show clockwise obliquity in distal view, running from centre to approx 3/8 of the way along side of the pentalith.
Pentalith diameter varies from about 1.5 to 7µm but in single samples all pentaliths are usually of very similar size. It is likely that several pseudo-cryptic species occur within the modern B. bigelowii (Takano et al. 2006, Hagino 2009).

Ecology & Biogeography: Neritic - predominanty observed in shelf seas, oceanic occurrences much rarer.

Biology & life-cycles: Never cultured, depite numerous attempts (J. Green, C. Klass, I. Probert, K. Hagino pers. coms.).

Search data:
TagsLITHS: nannolith-radiate, pentagonal,
CSPH: spherical, monomorphic, T-UNITS: all,
MetricsLith size: 2->12µm; Segments: 5->5; Coccosphere size: 4->24µm; Liths per sphere: 12->12
Sources: lith size (diameter) from Hagino et al. 2009; lith numbers assumed from geometry; csph size calculated
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: present in the plankton (Young et al. 2003)
First occurrence (base): within Cenomanian Stage (93.90-100.50Ma, base in Cenomanian stage). Data source: Burnett 1998

Plot of occurrence data:

References:

Burnett, J.A., (1998). Upper Cretaceous. In: Bown, P.R. (Editor), Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publications Series. Chapman & Hall, London, pp. 132-199.

Bybell, L.M. & Gartner, S., (1972). Provincialism among mid-Eocene calcareous nannofossils. Micropaleontology, 18(319-336).

Deflandre, G., (1947). Braarudosphaera nov. gen., type d'une famille nouvelle de Coccolithophorides actuels a elements composites. Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences. Paris, 225: 439-441.

Gran, H.H. & Braarud, T., (1935). A quantitative study of the phytoplankton in the Bay of Fundy and the Gulf of Maine (including observations on hydrography, chemistry and turbidity). Journal of the Biological Board of Canada, 1: 279-467.

Hagino, K.; Takano, Y. & Horiguchi, T., (2009). Pseudo-cryptic speciation in Braarudosphaera bigelowii (Gran and Braarud) Deflandre. Marine Micropaleontology, 72: 210-221.

Lecal-Schlauder, J., (1949). Notes preliminaires sur les coccolithophorides d'Afrique duNord. Bulletin de la Société d'Histoire Naturelle de l'Afrique du Nord, 4-(5-6): 160-167.

Lecal-Schlauder, J., (1951). Recherches morphologiques et biologiques sur les Coccolithophorides Nord-Africains. Annales de l'Institut Océanographique. Monaco & Paris, 26: 255-362.

Levin, H.L. & Joerger, A.P., (1967). Calcareous nannoplankton from the Tertiary of Alabama. Micropaleontology, 13: 163-182.

Martini, E., (1961). Nannoplankton aus dem Tertiär und der obersten Kreide von SW-Frankreich. Senckenbergiana lethaea, 42: 1-32.

Martini, E., (1971). Die Typen und Typoide des Natur-Museums Senckenberg, 46): Fossiles Nannoplankton. Senckenbergiana lethaea, 52: 115-127.

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.


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Braarudosphaera bigelowii compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 20-9-2018

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Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=146Go to Archive.is to create a permanent copy of this page - citation notes



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