Heterocapsa

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Heterocapsa
Scientific classification Edit this classification
Domain: Eukaryota
Clade: Sar
Superphylum: Alveolata
Phylum: Dinoflagellata
Class: Dinophyceae
Order: Peridiniales
Family: Heterocapsaceae
R.A. Fensome, F.J.R. Taylor, G. Norris, W.A.S. Sarjeant, D.I. Wharton & G.L. Williams
Genus: Heterocapsa
Stein

Heterocapsa is a genus of dinoflagellates belonging to the family Heterocapsaceae.[1] It is an unicellular photosynthetic dinoflagellate with thecal plates arranged as Po, cp, 5', 3a, 7'', 6c, 5s, 5''', 2'''' and extracellular, three-dimensional triradiate body scales. The genus is often found in worldwide algal blooms, causing harmful algal blooms (HABs) that devastate the environment or agriculture. Its mixotroph properties grants an advantage to its cosmopolitan distribution[2], being able to switch to phagotrophy, when light penetration is low.[3]

Characteristics

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Theca is the body armor that overlays the surface of many members of Peridiniales and Gonyaulacales (under Peridiniphycidae)[4], including Heterocapsa. It is mainly composed of cellulose secreted in the Amphiesmal Vesicles, which is right beneath the cell membrane and serves important functions and characters to dinoflagellates, as they are of SAR Super group.[5]

In Heterocapsa, the arrangement of theca is crucial for the identification of species[3]. Each has similar yet distinguishable thecal patterns from each others (e.g. cone-shape, oval-shape, antapical horn), this pattern is called "Tabulation". The first theory of how tabulation can be of significance to phylogeny was proposed by late Zoologist Charles Atwood Kofoid.

Thecal plates of this genus are categorized as following: epitheca, hypotheca, cingulum, sulcus. Each part is composed of various series of plates: apical, postcingular, sulcul, etc., and is denoted by numbers or letters and apostrophes, starting from the anterior-most series. The common tabulation series of Heterocapsa is: Po, cp, 5' , 3a, 7'' , 6c, 5s, 5''' , 2''''[3](abbreviation below).

(Pore plate, canal plate, apical plates, anterior intercalary plates, precingular plates, cingular plates, sulcul plates, postcingular plates, antapical plates.)

Tabulation Nomenclature[6]

Body scales

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Body scales is a very unique shared feature of Heterocapsa. It has been widely studied to identify certain species. However, no previous study had pounded the question of how does Heterocapsa produce its body scales. Some had speculated such process may be involved with the Golgi Apparatus, as scales were observed inside vesicles. Morphology of the body scales is a common triradiate basal plate, with vertical spines and longitudinal bars constructed on top of basal plate.

Organelles

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Like many other Dinoflagellates, the nucleus of Heterocapsa contains large amount of genetic information. Named Dinokaryon, DNA found inside is intensely condensed into a Liquid Crystal State.

Being photosynthetic, which isn't commonly seen in Dinoflagellates, Heterocapsa possesses reticulated chloroplast and pyrenoid. As suggested by Iwataki, 2008[3], the relative position of these two organelles may provide insights on distinguishing species with similar tabulation series. For instance, H. pygmaea has two pyrenoids in one cell. In H. circularisquama, the pyrenoid is located in the hypotheca, whereas in H. illdefina, it is located in the epitheca. Trichocyst for defensive mechanisms can also be observed in Heterocapsa.

Harmful algal blooms

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Many species under Heterocapsa have been reported causing algal blooms in late summer to winter, and all but blooms caused by H.rotundata in the Chesapeake Bay, Maryland, USA were not toxic. H.circularisquama on the other hand, is constantly found in HABs globally, especially from Japan, and with signs of intruding the Bay of Kuwait.[7] The hemolytic toxin[8][9] produced by H.circularisquama is lethal to bivalves and fishes[10][11], with reports of cardiac arrest to oyster farms in western Japan. Though the mechanism of toxin production is still unknown, some suggested the endosymbiotic bacteria[12] may have participate in the process.

Species

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[1]

References

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  1. ^ a b "Heterocapsa Stein, 1883". www.gbif.org. Retrieved 25 April 2021.
  2. ^ Guiry, M.D. & Guiry, G.M. (2023). Guiry MD, Guiry GM (eds.). "Heterocapsa Stein, 1883". AlgaeBase. National University of Ireland, Galway. World Register of Marine Species. Retrieved 5 December 2023.{{cite web}}: CS1 maint: multiple names: authors list (link)
  3. ^ a b c d Iwataki, Mitsunori (2008). "Taxonomy and identification of the armored dinoflagellate genus Heterocapsa (Peridiniales, Dinophyceae)". Plankton and Benthos Research. 3 (3): 135–142. Bibcode:2008PBenR...3..135I. doi:10.3800/pbr.3.135. ISSN 1880-8247.
  4. ^ "Present Classification of Modern Dinoflagellates", Fossil and Living Dinoflagellates, Elsevier, pp. 134–137, 1974, doi:10.1016/b978-0-12-619150-9.50017-2, ISBN 978-0-12-619150-9, retrieved 2025-12-04
  5. ^ Kwok, Alvin Chun Man; Chan, Wai Sun; Wong, Joseph Tin Yum (2023-01-20). "Dinoflagellate Amphiesmal Dynamics: Cell Wall Deposition with Ecdysis and Cellular Growth". Marine Drugs. 21 (2): 70. doi:10.3390/md21020070. ISSN 1660-3397. PMC 9959387. PMID 36827111.
  6. ^ Al-Yamani, Faiza; Saburova, Maria; Polikarpov, Igor (2012-01-01). "A preliminary assessment of harmful algal blooms in Kuwait's marine environment". Aquatic Ecosystem Health & Management. 15 (sup1): 64–72. Bibcode:2012AqEHM..15S..64A. doi:10.1080/14634988.2012.679450. ISSN 1463-4988.
  7. ^ Saburova, Maria; Al-Kandari, Manal; Polikarpov, Igor; Akbar, Abrar; Hussain, Sumaiah; Rahmeh, Rita; Al-Zakri, Waleed; Al-Yamani, Faiza (February 2022). "Alien toxic dinoflagellate Heterocapsa circularisquama from the Western Pacific in Kuwait, NW Indian Ocean". Deep Sea Research Part II: Topical Studies in Oceanography. 196 105027. Bibcode:2022DSRII.19605027S. doi:10.1016/j.dsr2.2022.105027.
  8. ^ Sato, Yoji; Oda, Tatsuya; Muramatsu, Tsuyoshi; Matsuyama, Yukihiko; Honjo, Tsuneo (February 2002). "Photosensitizing hemolytic toxin in Heterocapsa circularisquama, a newly identified harmful red tide dinoflagellate". Aquatic Toxicology. 56 (3): 191–196. Bibcode:2002AqTox..56..191S. doi:10.1016/S0166-445X(01)00191-6. PMID 11792435.
  9. ^ Miyazaki, Y; Iwashita, T; Yamaguchi, K; Oda, T; Matsuyama, Y; Honjo, T (September 2006). "Isolation and characterisation of photoactive haemolytic toxin fromHeterocapsa circularisquama". African Journal of Marine Science. 28 (2): 427–429. Bibcode:2006AfJMS..28..427M. doi:10.2989/18142320609504191. ISSN 1814-232X.
  10. ^ Matsuyama, Yukihiko (February 2012). "Impacts of the harmful dinoflagellate Heterocapsa circularisquama bloom on shellfish aquaculture in Japan and some experimental studies on invertebrates". Harmful Algae. 14: 144–155. Bibcode:2012HAlga..14..144M. doi:10.1016/j.hal.2011.10.019. ISSN 1568-9883.
  11. ^ Matsuyama, Yukihiko (February 2012). "Impacts of the harmful dinoflagellate Heterocapsa circularisquama bloom on shellfish aquaculture in Japan and some experimental studies on invertebrates". Harmful Algae. 14: 144–155. Bibcode:2012HAlga..14..144M. doi:10.1016/j.hal.2011.10.019.
  12. ^ Horiguchi, Takeo (1995). "Heterocapsa circularisquama sp. nov. (Peridiniales, Dinophyceae): A new marine dinoflagellate causing mass mortality of bivalves in Japan". Phycological Research. 43 (3): 129–136. doi:10.1111/j.1440-1835.1995.tb00016.x. ISSN 1440-1835. Retrieved 5 December 2025.