Nannotax3 - ntax_cenozoic - Trigonaspis Nannotax3 - ntax_cenozoic - Trigonaspis


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

Daughter taxa (time control age-window is: 0-800Ma)
Pappomonas borealis HOL
BCs flat plates, with monolayer of crystallites.
Tower coccoliths occur around coccosphere but higher at flagellar pole, centre of tube narrower;
Trigonaspis melvillea
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.
Trigonaspis minutissima
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
Pappomonas garrisonii HOL
BCs inconspicuous. Tower coccoliths occur around coccosphere but higher at flagellar pole.
Trigonaspis sp.


Citation: Trigonaspsis Thomsen 1980
taxonomic rank: Genus
Type species: Trigonaspsis diskoensis Thomsen 1980
Taxonomic discussion: The type species Trigonaspsis diskoensis is now known to be a life-cyle stage of Pappomonas so the genus is strictly redundant. 

Distinguishing features:
Parent taxon (open-tube): Holococcoliths with tube, open distally (or cover recessed)
This taxon: 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 to species level (Thomsen et al. 1991, 2015, Young unpubl. obs.).

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

Search data:
LITHS: holococcolith, elliptical, cylindrical, hollow, CA: vacant, process, CROSS-POLARS: V-prominent, R-prominent,
Lith size: 0.5->1.5µm; Coccosphere size: 2->8µm;
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: Total of ranges of the species in this database
First occurrence (base): within No known fossil record modern (0.00-0.00Ma, base in "Holocene" stage). Data source: Total of ranges of species in this database

Plot of occurrence data:


Thomsen, H. A. (1980). 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


Trigonaspis compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 23-2-2024

Taxon Search:
Advanced Search

Short stable page link: Go to to create a permanent copy of this page - citation notes

Nannotax is being sponsored through 2024 by Woodside Energy and Shell USA

Add Comment

* Required information
Captcha Image
Powered by Commentics


No comments yet. Be the first!