Trigonium Cleve, 1867
Holotype species: Trigonium arcticum (Brightwell) Cleve
Original publication and holotype designation: Cleve, P.T. (1867). Diatomaceer från Spetsbergen. Öfversigt af Kongl. Vetenskaps-Akademiens Förhandlingar, Stockholm 24(10): 661-670.
Taxonomic status: currently recognized as a distinct genus.
Most recent taxonomic treatment adopted: Nikolaev, V.A., Kociolek, J.P., Fourtanier, E., Barron, J.A. & Harwood, D.M. (2001). Late Cretaceous diatoms (Bacillariophyceae) from the Marca Shale member of the Moreno Formation, California. Occasional Papers of the California Academy of Sciences 152: -119, 39 pls.
Description: Cells tri- to multiangular, rectangular in girdle view. Plastids discoid. A marine genus growing in zig-zag chains attached to seaweeds; cosmopolitan but most widely distributed in warm waters. Also fossil, from the Late Eocene to the present. Valves triangular to multiangular, elevated at the corners; with deep, vertical mantles. Surface apparently smooth but at high magnification small granules can often be seen. areolae more-or-less simple, arranged in rows radiating from the centre, becoming smaller at the angles to form pseudocelli; closed externally by a layer of silica in which there is a ring of usually six pores, each closed by rotae. A septum occurs at each corner. Our figure suggests that there is a septum on the valvocopula. Rimoportulae low lying, clustered in the centre of the valve; their external openings are inconspicuous. Cingulum deep, containing porous, complete copulae.The most recent alteration to this page was made on 7 Dec 2015 by M.D. Guiry.
Comments: Hendey (1964) clarified Cleve's description and rejected later modifications. His concept of the genus seems now to be accepted (e.g. by Glezer, 1975 and Hoban, 1983) although Simonsen (1974) has a different concept, using the name for Triceratium alternans. Keeping to the Cleve-Hendey concept helps to bring some order to the confusion of tri- and multiangular taxa. Hoban (1983) discusses and figures the type species of Trigonium; our material of another species (T. formosum?) is clearly in the same genus.
Numbers of names and species: There are 45 species names in the database at present, as well as 13 infraspecific names. Of the species names, 9 have been flagged as accepted taxonomically on the basis of the listed literature under the species name. In some instances, opinions on taxonomic validity differ from author to author and users are encouraged to form their own opinion. AlgaeBase is a work in progress and should not be regarded as a definitive source only as a guide to the literature..
Names: ('C' indicates a name that is accepted taxonomically; 'S' a homotypic or heterotypic synonym; 'U' indicates a name of uncertain taxonomic status, but which has been subjected to some verification nomenclaturally; 'P' indicates a preliminary AlgaeBase entry that has not been subjected to any kind of verification. For more information on a species click on it to activate a link to the Species database):
Click here to also show infraspecific names in the list below.
Verification of data
Users are responsible for verifying the accuracy of information before use, as noted on the website Content page.
Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera, organised in the 1990s by Dr Bruce Parker on behalf of the Phycological Society of America (PSA) and intended to be published in CD format. These AlgaeBase descriptions are now being continually updated, and each current contributor is identified above. The PSA and AlgaeBase warmly acknowledge the generosity of all past and present contributors and particularly the work of Dr Parker.
Descriptions of chrysophyte genera were subsequently published in J. Kristiansen & H.R. Preisig (eds.). 2001. Encyclopedia of Chrysophyte Genera. Bibliotheca Phycologica 110: 1-260.
Created: 23 April 2002 by M.D. Guiry
Verified by: 07 December 2015 by M.D. Guiry
Linking to this page: http://www.algaebase.org/search/genus/detail/?genus_id=44473
Please cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 2021. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 28 September 2021.