Nematodinium Kofoid & Swezy, 1921

Holotype species: Nematodinium partitum Kofoid & Swezy

Original publication and holotype designation: Kofoid, C.A. & Swezy, O. (1921). The free-living unarmored Dinoflagellata. Memoirs of the University of California 5: i-viii, 1-562.

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Description: Unicellular biflagellated heterodynamic small to large (30-1110 µm long) cells of oval or fusiform shape, characterized by the possession of an ocelloid and nematocysts. Cell-body with torsion, the cingulum makes more than one to 2.5 loops. Consequently the sulcus is no straight furrow but follows the torsion of the cell, encircling the body up to 1.5 times. In some species the cingulum and sulcus extend to a tentacle-like protrusion of the posterior part of the cell. The ocelloid is composed of a lens, a retinoid and a pigment cup. This organelle is derived from chloroplasts and in some species chlorophyll can be detected by epifluorescence microscopy in the pigment cup. During binary cell division, the ocelloid is reorganized, the lens is fragmented. The nematocysts, called by other authors cnidocysts are presumably explosive organelle of unknown function. So far they have not been observed exploded. They have a complicated structure and resemble to those of Polykrikos Bütschli, differing in lacking a spiral thread. Chloroplasts present or absent. Cells often enclosed in a hyaline temporary cyst, sexual reproduction and resting cyst formation unknown. Habitat: Marine plankton, reported from cold-temperate to warm waters. One species is also recorded in the brackish waters of the Baltic Sea. The presence of a tentacle-like extension of the posterior cell part caused Greuet (1973) to separate the species earlier called Proterythropsis vigilans Marshall into a new genus Nematopsides. Sournia regards this taxon as not distinct from Nematodinium on genus level.

Information contributed by: M. Elbrächter. The most recent alteration to this page was made on 2017-05-23 by M.D. Guiry.

Taxonomic status: This name is of an entity that is currently accepted taxonomically.

Most recent taxonomic treatment adopted: Kawai, H. & Nakayama, T. (2015). Introduction (Heterokontobionta p.p.), Cryptophyta, Dinophyta, Haptophyta, Heterokontophyta (except Coscinodiscophyceae, Mediophyceae, Fragilariophyceae, Bacillariophyceae, Phaeophyceae, Eustigmatophyceae), Chlorarachniophyta, Euglenophyta. In: Syllabus of plant families. Adolf Engler's Syllabus der Pflanzenfamilien. Ed. 13. Phototrophic eukaryotic Algae. Glaucocystophyta, Cryptophyta, Dinophyta/Dinozoa, Haptophyta, Heterokontophyta/Ochrophyta, Chlorarachnniophyta/Cercozoa, Chlorophyta, Streptophyta p.p. (Frey, W. Eds), pp. 11-64, 103-139. Stuttgart: Borntraeger Science Publishers.

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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.

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M.D. Guiry in Guiry, M.D. & Guiry, G.M. 23 May 2017. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched on 04 March 2024

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