Blackites


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

Distinguishing features: Coccoliths process-bearing with complex base including outer rim, radial lath and lamellar cycles


Daughter taxa: (blue => in age window 0-800Ma) Granddaughter taxa
Spine low, globular, height<2x width

Spine conical, tapering with maximum width near base

Spine inflated with maximum width above base, many with conspicous bulge

Spine tall with narrow central opening

Spine absent or very small

Specimens which cannot be assigned to any established species

Taxonomy:

Citation: Blackites Hay & Towe, 1962
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 provisionally included here in Blackites. Most of these genera would fall within the Blackites morionum group as recognised here.
Notes & 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.

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

Distinguishing features: Coccoliths process-bearing with complex base including outer rim, radial lath and lamellar cycles


Morphology remarks: 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 cyles are consistently present, the processes however have highly variable structure including forms with multiple tiers of additional cycles. 


Size: Spin 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:
TagsLITHS: planolith, elliptical, CA: grill, PROCESS: hollow, spine,
CSPH: not known, DETAILS: ca_disjunct,
MetricsLith size: 4->30µm;
Sources:
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 Chattian Stage (100% up, 23Ma, in Chattian stage). Data source: Total of range of species in this database
First occurrence (base): in upper part of Thanetian Stage (62% up, 57.2Ma, in Thanetian stage). Data source: Total of range 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, 368 pp.GS

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

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

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

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


nannotaxlogo400px

Blackites compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 24-2-2019

Taxon Search:
Advanced Search

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



Comments (0)

No comments yet. Be the first!

Add Comment

* Required information
1000
Captcha Image
Powered by Commentics