Dinophysis Ehrenberg, 1839

Holotype species: Dinophysis acuta Ehrenberg

Original publication: Ehrenberg, C.G. (1841). Über noch jetzt zahlreich lebende Thierarten der Kreidebildung und den Organismus der Polythalamien. Abhandlungen der Königlichen Akademie der Wissenschaften zu Berlin 1839: 81-174, 4 pls.

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Type designated in: Loeblich, A.R. & Loeblich, A.R. (1966). Index to the genera, subgenera, and sections of the Pyrrhophyta. Studies in Tropical Oceanography 3: [i]-x, 1-94, 1 plate.

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Description: Small to medium-sized (25-100 µm) laterally more or less compressed cells with a cingulum and sulcus with good visible or even large lists. Cell of cellulosic thecal plates. Two large prominent hypothecal and epithecal plates joined by a serrated sagittal dorsal suture. Four more epithecal plates are small and one bears a ventral pore, and 2 more small hypothecal plates are located ventrally in the sulcal area but are not connected with the ventral flagellar pore. Cingulum consists of 2 large and 2 small plates, sulcus of 4 major plates and a very difficult to demonstrate internal plate, called sm, which is related to the flagellar pore platelets. In summary 19 plates. The 2 large hypothecal plates may have elaborated spines or may form 1-2 horns. The right sulcal list is part of the right hypothecal plate and has one or two ribs. It is always smaller than the left sulcal list with 2-3 ribs. Cingulum is either located very much anteriorly so that the epicone is very small and is more or less hidden by the cingular lists (typical Dinophysis) or the epicone is much larger, the cingulum may be even in the middle of the cell. These species have been earlier allocated to the genus Phalacroma Stein which is now regarded as a synonym of Dinophysis. Cingulum always circular, not displaced. Thecal plates are either smooth or have a more or less elaborated surface ornamentation like poroids, pores or reticulation. Nucleus is spherical or ovoid, in most species located in the hypocone. Rhabdosomes located in the cytoplasm, are an unusual type of organelle, related to trichocysts. A row of microtubules form a sort of microtubular basket near the flagellar pore. Most species are phototrophic with chloroplasts, others are heterotrophic obligate phagotrophs without chloroplasts but with 2 large pusules. As most of the apoplastidic species have earlier been allocated to Phalacroma, some authors regard this as a possible distinction between Dinophysis and Phalacroma but there are taxa of the typical Dinophysis morphology, with very small epicone, which do not have chloroplasts but others with a very large epicone of the Phalacroma-type which do have chloroplasts. The pigments and ultrastructure of chloroplasts are unusual for dinoflagellates. They include phycobilins like cryptophytes, and chloroplasts and surrounded only by 2 membranes also like cryptophytes. It is not quite clear whether they also contain the pigment peridinin which is restricted to dinoflagellates. Speculation exists that the chloroplasts may have come from cryptophycean endosymbionts or that dinophytes originally had chloroplasts with phycobilins and peridinin. Some species have chloroplasts but also have food vacuoles with more or less digested prey; thus mixotrophy may be common. This may explain why so far no species with chloroplasts has been cultivated. Food uptake of obligate heterotrophic species is by myzocytosis, they feed on ciliates by forming a long feeding tube with which they pierce the prey, sucking out the cell contents. Dinophysis-species may be parasitized by the dinophyte Amoebophrya Koeppen. There is some evidence for sexual reproduction, but so far this has not been proven unequivocally. Cyst formation is reported. Several phototrophic and at least one chloroplastless species contain toxins which may be concentrated in mussels and which cause the so-called DSP- symptoms when eaten. The toxins involved are okadaic acid and various related chemical compounds. The symptoms are prolonged gastroenteritis. Less than 1000 cells per liter are sufficient to produce toxic mussels. Toxic mussels are known from all continents. In France, in 1983 more than 3000 consumers of toxic mussels were affected. Most countries today have a good monitoring program, but apparently there is no strong correlation between the cell number and the toxin content of the mussels. Marine plankton from polar to tropical waters; many species exclusively oceanic, others common in coastal waters but may be accumulated by currents in inshore waters.

Information contributed by: M. Elbrächter. The most recent alteration to this page was made on 2020-01-31 by M.D. Guiry.

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

Gender: This genus name is currently treated as feminine.

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.

Comments: McMinn & Scott (2005: 206) record this as a member of thr Family Amphisoleniaceae.

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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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Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 31 January 2020. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 27 May 2024

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