Nannotax3 - ntax_cenozoic - Blackites Nannotax3 - ntax_cenozoic - Blackites

Blackites


Classification: ntax_cenozoic -> Syracosphaerales -> Rhabdosphaeraceae -> Blackites
Sister taxa: Acanthoica, Algirosphaera, Blackites, Cyrtosphaera, Discosphaera, Palusphaera, Rhabdosphaera, Solisphaera

Daughter taxa (time control age-window is: 0-800Ma)Granddaughter taxa
B. morionum group
Spine low, globular, height<2x width

B. clavus group
Spine conical, tapering with maximum width near base
Blackites bipartitus
Blackites clavus
Blackites dupuisii
Blackites gamai
Blackites spiculiformis
Blackites thiedei

B. inflatus group
Spine inflated with maximum width above base, many with conspicous bulge

B. spinosus group
Spine tall with narrow central opening

B. amplus group
Spine absent or very small
Blackites amplus
Blackites friedrichii
Blackites furvus
Blackites sp. - bases

Blackites sp.
Specimens which cannot be assigned to any established species

Taxonomy:

Citation: Blackites Hay & Towe, 1962
taxonomic rank: Genus
Type species: Discolithus spinosus Deflandre & Fert, 1954 = Blackites spinosus (Deflandre & Fert, 1954) Hay & Towe, 1962
Variants: The taxonomy outlined here is based on that of Bown (2005), and is essentially LM based. Other authors, most notably Shafik (1989) have separated various genera based on SEM studies using differences in the number of cycles in the base and process. Aubry (1999) reviews this work in depth. At present this taxonomy is difficult to apply and further SEM study of well-preserved material is needed, hence all these forms are included here in Blackites. Most of these genera would fall within the Blackites morionum group as recognised here.
Taxonomic discussion: Differentiated from Rhabdosphaera by the presence of a radial lath cycle, which is reduced in some species, but is present as a series of residual radial elements between the outer cycle and the lamellar cycle. Typically more than one radial lath cycle element to each rim element.

Distinguishing features:
Parent taxon (Rhabdosphaeraceae): BCs planoliths with radial lath cycle and highly-variable axial structures. Often polymorphic and/or varimorphic
This taxon: Coccoliths process-bearing with complex base including outer rim, radial lath and lamellar cycles

Original description: Coccoliths belonging to this genus are characterized by a single circular shield with a perforate ring spanned by interlocking ribs near the periphery. 

Farinacci & Howe catalog pages: Blackites + * , Amitha * , Cruxia * , Naninfula + * , Cepekiella * , Discoturbella * , Notiocyrtolithus * , Ommatolithus * , Pseudotriquetrorhabdulus * , Wiseorhabdus *


Morphology:

Spine- or process-bearing coccoliths with a base formed of three components:
1) a bicyclic outer rim (as in other Rhabdosphaeraceae);
2) a radial lath cycle (often with two laths per rim unit);
3) multiple lamellar cycles with clockwise obliquity.
These three cycles are consistently present, the processes however have highly variable structure, including forms with multiple tiers of additional cycles. 


Size:
Spine height varies very greatly, from about 4 to 30 µm (and forms without spines occur). Basal diameter seem to be much less variable, almost always being about 3-6 µm and with no significantly larger forms known.

Search data:
LITHS: planolith, elliptical, CA: ca_disjunct, grill, process,
Lith size: 4->30µm;
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): at top of Oligocene Epoch (100% up, 23Ma, in Aquitanian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within NP9 zone (55.86-57.21Ma, base in Thanetian stage). Data source: Total of ranges of species in this database

Plot of occurrence data:

References:

Aubry, M. -P. (1999). Handbook of Cenozoic calcareous nannoplankton. Book 5: Heliolithae (Zygoliths and Rhabdoliths). Micropaleontology Press, American Museum of Natural History, New York. 1-368. gs

Bown, P. R. & Newsam, C. (2017). Calcareous nannofossils from the Eocene North Atlantic Ocean (IODP Expedition 342 Sites U1403–1411). Journal of Nannoplankton Research. 37(1): 25-60. gs O

Bown, P. R. (2010). Calcareous nannofossils from the Paleocene/Eocene Thermal Maximum interval of southern Tanzania (TDP Site 14). Journal of Nannoplankton Research. 31(1): 11-38. gs O

Hay, W. W. & Towe, K. M. (1962a). Electron microscope examination of some coccoliths from Donzacq (France). Eclogae Geologicae Helvetiae. 55: 497-517. gs O

Shafik, S. (1989). Some new calcareous nannofossils from Upper Eocene and Lower Oligocene sediments in the Otway Basin, southeastern Australia. Alcheringa. 13: 69-83. gs

Varol, O. (1989b). Eocene calcareous nannofossils from Sile (northwest Turkey). Revista Española de Micropaleontología. 21: 273-320. gs


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Blackites compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 23-4-2024

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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=86 Go to Archive.is to create a permanent copy of this page - citation notes
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