Oxyrrhis marina, from Calkins (1901).

Belongs within: Myzozoa.
Contains: Oodiniaceae, Syndina, Noctilucales, Peridinea, Gyrodinium, Amphidinium.

The Dinoflagellata are a clade of unicellular eukaryotes with phycodnavirus-like basic chromatin proteins (Cavalier-Smith 2018).

Little whirling photosynthetic (and not so photosynthetic) thingies
Published 27 May 2007

Dinoflagellates are unicellular protists, generally accepted to form a clade called Alveolata with ciliates and sporozoans. They are most familiar to the general public as the main culprit behind toxic algal blooms. The main distinguishing feature of dinoflagellates is that they possess two distinct flagella—a fairly straight one that sticks out from the cell, and a wavy one that wraps around the cell, usually in a groove. Most dinoflagellates also have a distinctive nucleus that lacks histones, the proteins that DNA wraps around in other eukaryotes, and with chromosomes that don’t decondense between divisions. According to Fensome, Taylor et al. (1993), about half of dinoflagellates are photosynthetic, while the other half are mostly parasitic (some are both).

Generalised dinoflagellate, from Andrew MacRae’s Dinoflagellates.

Dinoflagellates have perhaps the worst taxonomy of any group of organisms—worse than fossil plants, worse than South American harvestmen, worse than hominins. You may be aware that there are separate taxonomic codes for plants and animals. There are organisms that are neither plants nor animals but, because the codes were developed before this was understood, protists are assigned to either the botanical or zoological codes depending on which they were traditionally regarded as. Photosynthetic protists are covered by the botanical code, mobile protists are zoological. Problem is, some protists are both photosynthetic and mobile. Dinoflagellates are probably the largest group of organisms that have been regarded by different workers as under different taxonomic codes. As a result, the literature is full of names for dinoflagellates that are valid under one code but not under the other, and cases different codes require different names for the same thing. Palaeontologists working on dinoflagellates agreed to use the botanical code after 1961, and Fensome, Taylor et al. (1993) suggested the same thing for neontological taxa.

The other major issue with dinoflagellates is reconciling the fossil and living taxa. Many dinoflagellates form resistant vegetative cysts at some stage in the life-cycle, and these are the only stage that can be fossilised. Fossil taxonomy, therefore, is based on these. Neontological taxonomy, however, is generally based on the motile stage of the cycle. As a result, two separate taxonomies have developed in parallel, and there are relatively few cases where a cyst can be connected with a motile form. The worst case of this problem involves the fossil genus Spiniferites Mantell 1850, which has long been known to represent the cyst of the living genus Gonyaulax Diesing 1866. Unfortunately, because both of these genera are quite large and involve a lot of species, most workers have turned something of a blind eye to this point, and no real solution has been developed.

Pseudo-worms and such
Published 28 May 2007

In the Fensome, Taylor et al. (1993) classification of dinoflagellates, Blastodiniales were a group of extracellular parasites with a dinokaryon (the distinctive dinoflagellate nucleus) for only part of their complicated life cycles. Blastodiniales were a diverse group and Fensome et al. made no secret of its probable polyphyly. Most families of Blastodiniales start out as a trophont (feeding stage) attached to the host by rhizoids, a peduncle or a stylet (the exception is Blastodinium, in which the trophont is not actually attached but resides within the gut of copepods). The trophont may produce spores while attached and feeding (palisporogenesis), or may detach first before producing spores (palintomy). The spores are eventually released as motile dinospores, that have been recorded fusing to form gametes in at least some taxa, or give rise directly to the new generation of trophonts. Plastids are present in Blastodininium and Protoodinium whereas other Blastodiniales are non-photosynthetic.

In Cachonella (Cachonellaceae), the trophont is attached to its siphonophore host by rhizoids. When it is finished feeding, it detaches and develops long tubular processes within the host’s gut (the illustration in Fensome et al. has definite B-grade sci-fi appeal). After being passed from the host, the ex-trophont produces coccoid aplanospores (non-motile spores) that in turn remain attached to each other while shedding a series of cyst membranes, to form a branching structure with a spore at the end of each branch. Eventually the non-motile aplanospores give rise to motile dinospores.

Haplozoon is a very distinctive form that Fensome et al. assigned to Blastodiniales (though Leander et al. (2002) disputed this position, as Haplozoon appears to possess a dinokaryon throughout its life-cycle). Haplozoon initially attaches to its host (a larvacean or annelid) as a unicellular trophont by a stylet. It then undergoes multiple cell divisions to give rise to a flat worm- or ribbon-like (apparently) multicellular form with a single trophocyte (feeding cell), multiple rows of gonocytes (dividing cells) and a distal row of sporocytes (spore-producing cells). The single nuclei of the sporocytes become four, and individual sporocytes are released as cysts (probably eventually releasing four dinospores, but this doesn’t appear to have actually been observed). Though the mature stage of Haplozoon has generally been interpreted as multicellular (or colonial), Leander et al. found that SEM images of H. axiothellae appeared to show a single continuous membrane covering all “cells”, and so interpreted Haplozoon as forming a unique compartmentalised syncytium (multinucleate single cell).

The non-photosynthetic Syndiniales possess dinoflagellate-like flagella, but do not possess a dinokaryon. In the Syndiniaceae, the trophont is a multinucleate plasmodium. In the Sphaeriparaceae, the trophont produces a long chain of aplanospores that are eventually released as dinospores.

Amoebophrya is a member of Syndiniales whose trophont develops a large conical cavity, the mastigocoel, in which multiple flagella are formed before the entire structure flips inside-out to give rise to a long worm-like, multinucleate, multiflagellate, mobile stage, the vermiform. The vermiform then undergoes multiple cleavages to form hundreds of individual dinospores.

Systematics of Dinoflagellata
<==Dinoflagellata (see below for synonymy)
    |--Arpylorus Calandra 1964 [Arpyloraceae]FT93
    |    `--A. antiquus Calandra 1964FT93
    |    |--Myzodinida [Myzodinea]C-S18
    |    |    |--Psammosa Okamoto et al. 2012 [Psammosidae]C-S18
    |    |    `--Colpovora Cavalier-Smith 2018 [Colpovoridae]C-S18
    |    |         `--*C. ungiis (Patterson & Simpson 1996) [=Colpodella unguis]C-S18
    |    `--Oxyrrhinales [Oxyrrhea, Oxyrrhia, Oxyrrhida]FT93
    |         |--‘Glyphidium’ Fresenius 1865 non Massal. 1860FT93
    |         `--Oxyrrhis Dujardin 1841JG17, FT93 [Oxyrrhinaceae]
    |              |--*O. marina Dujardin 1841SW70
    |              |--O. maritima Van Meel 1969S73
    |              `--O. tentaculifera Conrad 1939S73
            `--Eudinea [Dinophyceae, Gymnodiniphycidae]C-S18
                 |  i. s.: CeratoperidiniaceaeAB19
                 |           |--KirithraAB19
                 |           `--Ceratoperidinium Margalef ex Loeblich 1980FT93
                 |                `--C. yeye Margalef 1969S73
                 |         Levanderina Moestrup et al. 2014AB19
                 |         Margalefidinium Gómez, Richlen & Anderson 2017AB19
Dinoflagellata incertae sedis:
  Yalkalpodium scutum Morgan 1980RC02
  Downiesphaeridium Islam 1993QS03
    `--D. armatum (Deflandre) Islam 1993RC02
  Sepispinula ancorifera (Cookson & Eisenack) Islam 1993RC02
  Cysta moebii (Jörgensen) Loeblich & Loeblich 1970 [=Pterosphaera moebii]S73
  Halophilodinium Loeblich & Loeblich 1966 (see below for synonymy)FT93
    `--H. gessneri (Schiller) Loeblich & Loeblich 1968 [=Haematodinium gessneri Schiller 1956]S73
  Agrosphaera Lo Bianco 1903FT93
  Geodinium Chodat 1921 [incl. Chlorodinium Chodat 1921 (n. n.)]FT93
  Gleba Bruguière 1791 non Forskal 1776 (ICZN)FT93
  Glenoaulax Diesing 1866FT93
  Parapodinium Chatton 1920FT93
  Proaulax Diesing 1866FT93
  Radiozoum Mingazzini 1904FT93
  ‘Diplocystis’ Cleve 1901 nec Berkeley & Curtis 1869 nec Künstler 1887 (ICZN0 nec Agardh 1896FT93
  Paralecaniella Cookson & Eisenack 1970E77
    `--*P. indentata (Deflandre & Cookson) Cookson & Eisenack 1970 (see below for synonymy)E77
  Wanea Cookson & Eisenack 1958E77
    `--*W. spectabilis (Deflandre & Cookson) Cookson & Eisenack 1958 (see below for synonymy)E77
  Fromea Cookson & Eisenack 1958E77, FT93
    |--*F. amphora Cookson & Eisenack 1958E77
    `--F. staveia Elsik 1977E77
  Hypodium sphericumSW70
  Cabra mattaSMO10
  Pseudothecadinium campbeliiSMO10
  Pronoctiluca Fabre-Domergue 1889FT93, GE87 (see below for synonymy)
    |--*P. pelagica Fabre-Domerague 1889SW70
    |--P. acutaSW70
    `--P. spiniferaGE87
  Bonetocardiella Dufour 1968 [Bonetocardiellidae]HW93
  Schuettiella mitra [incl. Oxytoxum gigas Kofoid 1907]G18

Dinoflagellata [Adiniferae, Adinophycidae, Amphilothales, Athecatales, Cilioflagellata, Desmocapsineae, Desmokontae, Desmomonadineae, Desmophyceae, Dinifera, Diniferae, Diniferida, Diniferidea, Diniferina, Diniferophycidae, Dinocapsales, Dinocapsineae, Dinococcales, Dinococcineae, Dinococcophycidae, Dinoflagellatae, Dinoflagellatophycidae, Dinoflagelliae, Dinoflagellida, Dinoflagellidea, Dinoflagellidia, Dinokontae, Dinomastigota, Dinomonadea, Dinophyta, Dinotrichales, Dinotrichineae, Endoflagellatophycidae, Kolkwitziellales, Mesocaryota, Peridineae, Peridiniaea, Peridinieae, Peridinina, Peridiniophyceae, Peridinophyceae, Phytodinierae, Phytodinozoa, Pyrrhophycophyta, Pyrrhophyta, Pyrrophyta, Rhizodineae, Rhizodininae, Thecatales]

Halophilodinium Loeblich & Loeblich 1966 [=Haematodinium Schiller 1956 non Hematodinium Chatton & Poisson 1930]FT93

*Paralecaniella indentata (Deflandre & Cookson) Cookson & Eisenack 1970 [=Epicephalopyxis indentata Deflandre & Cookson 1955]E77

Pronoctiluca Fabre-Domergue 1889GE87, FT93 [incl. Pelagorhynchus Pavillard 1917FT93, Protodinifer Kofoid & Swezy 1921FT93]

*Wanea spectabilis (Deflandre & Cookson) Cookson & Eisenack 1958 [=Epicephalopyxis spectabilis Deflandre & Cookson 1955]E77

*Type species of generic name indicated


[AB19] Adl, S. M., D. Bass, C. E. Lane, J. Lukeš, C. L. Schoch, A. Smirnov, S. Agatha, C. Berney, M. W. Brown, F. Burki, P. Cárdenas, I. Čepička, L. Chistyakova, J. del Campo, M. Dunthorn, B. Edvardsen, Y. Eglit, L. Guillou, V. Hampl, A. A. Heiss, M. Hoppenrath, T. Y. James, A. Karnkowska, S. Karpov, E. Kim, M. Kolisko, A. Kudryavtsev, D. J. G. Lahr, E. Lara, L. Le Gall, D. H. Lynn, D. G. Mann, R. Massana, E. A. D. Mitchell, C. Morrow, J. S. Park, J. W. Pawlowski, M. J. Powell, D. J. Richter, S. Rueckert, L. Shadwick, S. Shimano, F. W. Spiegel, G. Torruella, N. Youssef, V. Zlatogursky & Q. Zhang. 2019. Revisions to the classification, nomenclature, and diversity of eukaryotes. Journal of Eukaryotic Microbiology 66: 4–119.

[AS12] Adl, S. M., A. G. B. Simpson, C. E. Lane, J. Lukeš, D. Bass, S. S. Bowser, M. W. Brown, F. Burki, M. Dunthorn, V. Hampl, A. Heiss, M. Hoppenrath, E. Lara, E. Le Gall, D. H. Lynn, H. McManus, E. A. D. Mitchell, S. E. Mozley-Stanridge, L. W. Parfrey, J. Pawlowski, S. Rueckert, L. Shadwick, C. L. Schoch, A. Smirnov & F. W. Spiegel. 2012. The revised classification of eukaryotes. Journal of Eukaryotic Microbiology 59 (5): 429–493.

[C-S18] Cavalier-Smith, T. 2018. Kingdom Chromista and its eight phyla: a new synthesis emphasising periplastid protein targeting, cytoskeletal and periplastid evolution, and ancient divergences. Protoplasma 255: 297–357.

[C-SC04] Cavalier-Smith, T., & E. E. Chao. 2004. Protalveolate phylogeny and systematics and the origins of Sporozoa and dinoflagellates (phylum Myzozoa nom. nov.) European Journal of Protistology 40: 185–212.

[E77] Elsik, W. C. 1977. Paralecaniella indentata (Defl. & Cooks. 1955) Cookson & Eisenack 1970 and allied dinocysts. Palynology 1: 95–102.

[FT93] Fensome, R. A., F. J. R. Taylor, G. Norris, W. A. S. Sarjeant, D. I. Wharton & G. L. Williams. 1993. A classification of living and fossil dinoflagellates. Micropaleontology Special Publication 7: i–viii, 1–351.

[GE87] Gaines, G., & M. Elbrächter. 1987. Heterotrophic nutrition. In: Taylor, F. J. R. (ed.) The Biology of Dinoflagellates pp. 224–268. Blackwell Scientific.

[G18] Gómez, F. 2018. A review on the synonymy of the dinoflagellate genera Oxytoxum and Corythodinium (Oxytoxaceae, Dinophyceae). Nova Hedwigia 108 (1–2): 141–165.

[HW93] Hart, M. B., & C. L. Williams. 1993. Protozoa. In: Benton, M. J. (ed.) The Fossil Record 2 pp. 43–70. Chapman & Hall: London.

[JG17] Janouškovec, J., G. S. Gavelis, F. Burki, D. Dinh, T. R. Bachvaroff, S. G. Gornik, K. J. Bright, B. Imanian, S. L. Strom, C. F. Delwiche, R. F. Waller, R. A. Fensome, B. S. Leander, F. L. Rohwer & J. F. Saldarriaga. 2017. Major transitions in dinoflagellate evolution unveiled by phylotranscriptomics. Proceedings of the National Academy of Sciences of the USA 114 (2): E171–E180.

Leander, B. S., J. R. Saldarriaga & P. J. Keeling. 2002. Surface morphology of the marine parasite Haplozoon axiothellae Siebert (Dinoflagellata). European Journal of Protistology 38: 287–297.

[QS03] Quattrocchio, M. E., & W. A. S. Sarjeant. 2003. Dinoflagellates from the Chorrillo Chico Formation (Paleocene) of southern Chile. Ameghiniana 40 (2): 129-153.

[RC02] Riding, J. B., & J. A. Crame. 2002. Aptian to Coniacian (Early – Late Cretaceous) palynostratigraphy of the Gustav Group, James Ross Basin, Antarctica. Cretaceous Research 23: 739-760.

[SMO10] Selina, M. S., T. V. Morozova & T. Yu. Orlova. 2010. Dinoflagellates in epiphytic assemblage of Peter the Great Bay, sea of Japan. In: China-Russia Bilateral Symposium: Proceedings of the China-Russia Bilateral Symposium of “Comparison on Marine Biodiversity in the Northwest Pacific Ocean”, 10–11 October 2010, Qingdao (China) pp. 61–65. Institute of Oceanology, Chinese Academy of Sciences; A. V. Zhirmunsky Institute of Marine Biology, Far East Branch of the Russian Academy of Sciences.

[S73] Sournia, A. 1973. Catalogue des espèces et taxons infraspécifiques de Dinoflagellés marins actuels publiés depuis la révision de J. Schiller. I. Dinoflagellés libres. Beihefte zur Nova Hedwigia 48: 1–92.

[SW70] Steidinger, K. A., & J. Williams. 1970. Dinoflagellates. Memoirs of the Hourglass Cruises 2: 1–251.

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