Trigonaspis


Classification: Coccolithophores -> Holococcoliths -> open-tube -> Trigonaspis
Sister taxa: Calicasphaera, Papposphaera HOL, Trigonaspis,

Daughter taxa: (blue => in age window 0-800Ma)
BCs flat plates, with monolayer of crystallites.
Tower coccoliths occur around coccosphere but higher at flagellar pole, centre of tube narrower;
BCs are only slightly raised above the baseplate.
Tower coccoliths only at flagellar pole, with slender tube ending distally in a single distally directed triangular plate.
Similar to T. diskoensis but smaller (cells 2-3.5µm vs 5-6µm; CFCs 1-1.5µm vs 1.5-2.5µm high). Tower coccoliths only at flagellar pole
BCs inconspicuous. Tower coccoliths occur around coccosphere but higher at flagellar pole.

Taxonomy:

Citation: Trigonaspsis Thomsen 1980
Rank: Genus
Type species: Trigonaspsis diskoensis Thomsen 1980

Distinguishing features: Holococcoliths formed of triangular crystallite groups (ca. 0.15 µm across), each composed of three (?hexagonal) sub-units.
Dimorphic CFCs tower-like, BCs simple disks.

Farinacci & Howe catalog pages: Trigonaspis *


Biology & life-cycles: Trigonaspis holococcoliths have been observed forming combination coccospheres with Pappomonas borealis,  and P. garrisonii although the holococcoliths could not be identified species level (Thomsen et al. 1991, 2015, Young unpubl. obs.).

Search data:
TagsLITHS: holococcolith, flaring distally, tubular, sub-circular, CA: H: fabric-triangular-xtals, vacant, PROCESS: flaring, V-UNITS: px-plate, R-UNITS: spine,
MetricsLith size: 0.5->1.5µm; Coccosphere size: 2->8µm;
Sources:
The morphological data given here can be used on the advanced search page. See also these notes

See also: Pappomonas - alternate life-cycle phase of at least some species;

Geological Range:
Last occurrence (top): Extant Data source: Total of range of species in this database
First occurrence (base): at top of No known fossil record modern (100% up, 0Ma, in stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Thomsen, H. A. (1980d). Two species of Trigonaspis gen. nov. (Prymnesiophyceae) from West Greenland. Phycologia. 19(3): 218-229. gs

Thomsen, H. A., Ostergaard, J. B. & Hansen, L. E. (1991). Heteromorphic life histories in Arctic coccolithophorids (Prymnesiophyceae). Journal of Phycology. 27: 634-642. gs

Thomsen, H. A., Ostergaard, J. B. & Cros, L. (2015). Ventimolina stellata gen. et sp. nov. (Haptophyta, Papposphaeraceae) from warm water regions. Acta Protozoologica. 54: 275-281. gs


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Trigonaspis compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 18-10-2019

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Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=1433 Go to Archive.is to create a permanent copy of this page - citation notes



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