Nannotax3 - ntax_cenozoic - Alisphaera Nannotax3 - ntax_cenozoic - Alisphaera

Alisphaera


Classification: ntax_cenozoic -> Coccolith families inc sed -> Alisphaeraceae -> Alisphaera
Sister taxa: Alisphaera, Canistrolithus, Polycrater phase

Daughter taxa (time control age-window is: 0-800Ma)
A. capulata group - distal flange with sub-vertical extension
Alisphaera capulata
Flange extension L-shaped, sub-vertical. Teeth weakly developed. Central area elements short, leaving wide central opening instead of narrow fissure (but organic scale often present in central area).
Alisphaera memoria
Flange extension angular, sub-vertical, with central tooth, extending the full length of the central area. Teeth absent.
Alisphaera ordinata
Flange extension rounded, sub-vertical, extending the full length of the central area. Teeth well-developed.
Alisphaera quadrilatera
Flange extension, angular with sub-parallel sides and pointed end, sub-vertical. Similar to A. capulata but with distinct central fissure and flange extension simpler. Teeth weakly develped or absent.
A. extenta group - distal flange with wing-like extension
Alisphaera extenta
Flange extended into pointed wing. In oblique and side views it can be seen that the wing flares upwards and ends in sub-vertical wall. Teeth absent.
Alisphaera gaudii
Varimorhic, flange extended into a sharply pointed spur only in some specimens. Teeth well-developed.
A. unicornis group - distal flange with spike-like protrusion formed from a single element, or smooth
Alisphaera unicornis
Most coccoliths with well-developed horn-like spine on left-side of the broad margin of the flange. Teeth absent.
Alisphaera spatula
Spine centrally placed and with broad base. Teeth well-developed
Alisphaera bidentata
Like A. spatula but varimorphic, many coccoliths lack the spine. Teeth well-developed, and large nodules and at the ends of the central area.
Alisphaera pinnigera
Varimorphic, most coccoliths with no spine, a few with a sharp spike-like spine. Coccoliths also smaller and smoother than those of A. unicornis with narrower central area. Teeth variably developed
Alisphaera sp.
Specimens which cannot be assigned to established species

Taxonomy:

Citation: Alisphaera Heimdal, 1973
taxonomic rank: Genus
Type species: Acanhoica ordinata Kampnter 1941
Synonyms:
Taxonomic discussion: The species-level taxonomy of the genus was reviewed by Jordan & Chamberlain (1993) and by Kleijne et al. (2002). N.B. As well as describing new species Kleijne et al (2002) significantly revised the taxonomic concepts of A. unicornis and A. spatula. Essentially A. unicornis sensu Jordan & Chamberlain (1993) corresponds to A. gaudii whilst A. spatula sensu Jordan & Chamberlain (1993) corresponds to A. unicornis sensu Kleijne et al. (2002). The confusion stems from the fact that Okada & McIntyre (1977) illustrated two rather different specimens as A. unicornis, See Kleijne et al. (2002) for detailed synonymies.

Species characters. Species are primarily separated based on three characters:
  1. The nature of the flange-extenson, this varies from a simple spike delveloped on one element to a broad sub-vertical wall. Each species has a distinct style of flange extension.
  2. Varimorphism - in most species all coccoliths have similar flange extension but in A. guadii, A. bidentata and A. pinnigera typically less than half the coccoliths have the flange extension.
  3. Development of teeth along the back edge of the central area. In most species the teeth are consistently present but in others they are typically absent  - notably A. unicornis and A. extenta.
In addition A. unicornis coccoliths are larger than most others (2-3 µm vs 1-2 µm according to Kleijne et al. 2002) and in  A. capulata the central area is broader and more open. 

Distinguishing features:
Parent taxon (Alisphaeraceae): Heterococcoliths asymetric, arranged in meridional rows on coccosphere; V-unit forms flange, R-unit basal. Also nannolith phase "Polycrater" with quadrate aragonitic liths.
This taxon: Coccoliths placolith-like, with asymmetrical distal flange

Farinacci & Howe catalog pages: Alisphaera + + *


Morphology:

Coccosphere monothecate, ellipsoidal with apical opening. Coccoliths arranged on coccosphere with long axis aligned equatorially and broader flange directed toward apical opening. On some species the flange development varies significantly between coccoliths on a single coccosphere Kleijne et al. (2002) described this as dimorphism, we prefer to describe this varimorphism since there is normally a continuum from specimens with no protrusion to specimens with a well-developed protrusion.
Coccoliths placolith-like, with asymmetrical distal flange, one side broader with a variable extension, other side narrow and in many species with 8-10 teeth (or "nodules") projecting into the central area. Plate in central area formed by extension of tube elements inward, usually with an irregular central fissure. No discrete circum-flagellar coccoliths.

Heterococcolith structure
- see Alisphaeraceae, and diagrams above


Biology & life-cycles

Combination cells of Polycrater sp. and Alisphaera gaudii have been observed (Cros et al. 2000, Cros & Fortuño 2002), and of P. galapagensis with A. unicornis (Supraha et al. 2018).

Search data:
LITHS: placolith, asymmetric, elliptical, CA: ca_conjunct,
CSPH: equant, monomorphic, CROSS-POLARS: V-prominent, R-prominent,
Lith size: 1->3µm; Coccosphere size: 4.5->16µm;
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Notes: Only occasional specimens observed and these are probably best referred to as Alisphaera sp.
Last occurrence (top): Extant. Data source: Total of ranges of the species in this database
First occurrence (base): within Quaternary Period (0.00-2.59Ma, base in Gelasian stage). Data source: Total of ranges of species in this database

Plot of occurrence data:

References:

Cros, L. & Fortuño, J. -M. (2002). Atlas of northwestern Mediterranean coccolithophores. Scientia Marina. 66: 1-186. gs

Cros, L., Kleijne, A. & Young, J. R. (2000a). Coccolithophorid diversity in the genus Polycrater and possible relationships with other genera. Journal of Nannoplankton Research. 22(2): 92-92. gs

Heimdal, B. R. (1973). Two new taxa of Recent coccolithophorids. “Meteor” Forschungsergebnisse. 70-75. gs

Kleijne, A., Jordan, R. W., Heimdal, B. R., Samtleben, C., Chamberlain, A. H. L. & Cros, L. (2002). Five new species of the coccolithophorid genus Alisphaera (Haptophyta) with notes on their distribution, coccolith structure and taxonomy. Phycologia. 40(6): 583-601. gs

Manton, I. & Oates, K. (1980). Polycrater galapagensis gen. et sp. nov., a putative coccolithophorid from the Galapagos Islands with an unusual aragonitic periplast. British Phycological Journal. 15: 95-103. gs

Supraha, L., Ljubesic, Z. & Henderiks, J. (2018). Combination coccospheres from the Eastern Adriatic coast: New, verified and possible life-cycle associations. Marine Micropaleontology. 141: 23-30. gs

Young, J. R., Geisen, M., Cros, L., Kleijne, A., Probert, I. & Ostergaard, J. B. (2003). A guide to extant coccolithophore taxonomy. Journal of Nannoplankton Research. S1: 1-132. gs


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Alisphaera compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 26-5-2024

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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=26 Go to Archive.is to create a permanent copy of this page - citation notes
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