{{Short description|Genus of protists}} {{Automatic taxobox |image = Heterocapsa_rotundata_2.jpg |image_caption = |parent_authority = R.A. Fensome, F.J.R. Taylor, G. Norris, W.A.S. Sarjeant, D.I. Wharton & G.L. Williams |taxon = Heterocapsa |authority = Stein }}
'''''Heterocapsa''''' is a genus of dinoflagellates belonging to the family ''Heterocapsaceae.''<ref name="GBIF2">{{cite web |title=Heterocapsa Stein, 1883 |url=https://www.gbif.org/species/8022260 |access-date=25 April 2021 |website=www.gbif.org |language=en}}</ref> It is an unicellular photosynthetic dinoflagellate with thecal plates arranged as Po, cp, 5<nowiki>', 3a, 7'', 6c, 5s, 5''', 2''''</nowiki> 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,<ref name="WoRMS2">{{cite WoRMS|title=''Heterocapsa'' Stein, 1883|id=109540|access-date=5 December 2023|author=Guiry, M.D. & Guiry, G.M.|db=AlgaeBase|year=2023}}</ref> being able to switch to phagotrophy, when light penetration is low.<ref name=":0">{{Cite journal |last=Iwataki |first=Mitsunori |date=2008 |title=Taxonomy and identification of the armored dinoflagellate genus Heterocapsa (Peridiniales, Dinophyceae) |url=https://www.jstage.jst.go.jp/article/pbr/3/3/3_3_135/_article |journal=Plankton and Benthos Research |language=en |volume=3 |issue=3 |pages=135–142 |doi=10.3800/pbr.3.135 |bibcode=2008PBenR...3..135I |issn=1880-8247|hdl=10069/23074 |hdl-access=free }}</ref>
== Characteristics == Theca is the body armor that overlays the surface of many members of Peridiniales and Gonyaulacales (under Peridiniphycidae),<ref>{{Citation |title=Present Classification of Modern Dinoflagellates |date=1974 |work=Fossil and Living Dinoflagellates |pages=134–137 |url=https://doi.org/10.1016/b978-0-12-619150-9.50017-2 |access-date=2025-12-04 |publisher=Elsevier |doi=10.1016/b978-0-12-619150-9.50017-2 |isbn=978-0-12-619150-9|url-access=subscription }}</ref> 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.<ref>{{Cite journal |last1=Kwok |first1=Alvin Chun Man |last2=Chan |first2=Wai Sun |last3=Wong |first3=Joseph Tin Yum |date=2023-01-20 |title=Dinoflagellate Amphiesmal Dynamics: Cell Wall Deposition with Ecdysis and Cellular Growth |journal=Marine Drugs |language=en |volume=21 |issue=2 |pages=70 |doi=10.3390/md21020070 |doi-access=free |issn=1660-3397 |pmc=9959387 |pmid=36827111}}</ref>
In ''Heterocapsa'', the arrangement of theca is crucial for the identification of species.<ref name=":0" /> Each has similar yet distinguishable thecal patterns from each other's (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<nowiki>''</nowiki> , 6c, 5s, 5<nowiki>'''</nowiki> , 2'<nowiki>'''</nowiki><ref name=":0" />(abbreviation below).
(Pore plate, canal plate, apical plates, anterior intercalary plates, precingular plates, cingular plates, sulcul plates, postcingular plates, antapical plates.) thumb|Tabulation Nomenclature<ref>{{Cite journal |last1=Al-Yamani |first1=Faiza |last2=Saburova |first2=Maria |last3=Polikarpov |first3=Igor |date=2012-01-01 |title=A preliminary assessment of harmful algal blooms in Kuwait's marine environment |url=https://doi.org/10.1080/14634988.2012.679450 |journal=Aquatic Ecosystem Health & Management |volume=15 |issue=sup1 |pages=64–72 |doi=10.1080/14634988.2012.679450 |bibcode=2012AqEHM..15S..64A |issn=1463-4988|url-access=subscription }}</ref>
=== Body scales === 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 === 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,<ref name=":0" /> 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 === 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.<ref>{{Cite journal |last1=Saburova |first1=Maria |last2=Al-Kandari |first2=Manal |last3=Polikarpov |first3=Igor |last4=Akbar |first4=Abrar |last5=Hussain |first5=Sumaiah |last6=Rahmeh |first6=Rita |last7=Al-Zakri |first7=Waleed |last8=Al-Yamani |first8=Faiza |date=February 2022 |title=Alien toxic dinoflagellate Heterocapsa circularisquama from the Western Pacific in Kuwait, NW Indian Ocean |url=https://linkinghub.elsevier.com/retrieve/pii/S0967064522000121 |journal=Deep Sea Research Part II: Topical Studies in Oceanography |language=en |volume=196 |article-number=105027 |doi=10.1016/j.dsr2.2022.105027 |bibcode=2022DSRII.19605027S |url-access=subscription }}</ref> The hemolytic toxin<ref>{{Cite journal |last1=Sato |first1=Yoji |last2=Oda |first2=Tatsuya |last3=Muramatsu |first3=Tsuyoshi |last4=Matsuyama |first4=Yukihiko |last5=Honjo |first5=Tsuneo |date=February 2002 |title=Photosensitizing hemolytic toxin in Heterocapsa circularisquama, a newly identified harmful red tide dinoflagellate |url=https://linkinghub.elsevier.com/retrieve/pii/S0166445X01001916 |journal=Aquatic Toxicology |language=en |volume=56 |issue=3 |pages=191–196 |doi=10.1016/S0166-445X(01)00191-6 |pmid=11792435 |bibcode=2002AqTox..56..191S |url-access=subscription }}</ref><ref>{{Cite journal |last1=Miyazaki |first1=Y |last2=Iwashita |first2=T |last3=Yamaguchi |first3=K |last4=Oda |first4=T |last5=Matsuyama |first5=Y |last6=Honjo |first6=T |date=September 2006 |title=Isolation and characterisation of photoactive haemolytic toxin from''Heterocapsa circularisquama'' |url=https://doi.org/10.2989/18142320609504191 |journal=African Journal of Marine Science |volume=28 |issue=2 |pages=427–429 |doi=10.2989/18142320609504191 |bibcode=2006AfJMS..28..427M |issn=1814-232X|url-access=subscription }}</ref> produced by ''H.circularisquama'' is lethal to bivalves and fishes,<ref>{{Cite journal |last=Matsuyama |first=Yukihiko |date=February 2012 |title=Impacts of the harmful dinoflagellate Heterocapsa circularisquama bloom on shellfish aquaculture in Japan and some experimental studies on invertebrates |url=https://doi.org/10.1016/j.hal.2011.10.019 |journal=Harmful Algae |volume=14 |pages=144–155 |doi=10.1016/j.hal.2011.10.019 |bibcode=2012HAlga..14..144M |issn=1568-9883|url-access=subscription }}</ref><ref>{{Cite journal |last=Matsuyama |first=Yukihiko |date=February 2012 |title=Impacts of the harmful dinoflagellate Heterocapsa circularisquama bloom on shellfish aquaculture in Japan and some experimental studies on invertebrates |url=https://linkinghub.elsevier.com/retrieve/pii/S1568988311001478 |journal=Harmful Algae |language=en |volume=14 |pages=144–155 |doi=10.1016/j.hal.2011.10.019 |bibcode=2012HAlga..14..144M |url-access=subscription }}</ref> 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<ref>{{cite journal |last1=Horiguchi |first1=Takeo |title=Heterocapsa circularisquama sp. nov. (Peridiniales, Dinophyceae): A new marine dinoflagellate causing mass mortality of bivalves in Japan |journal=Phycological Research |date=1995 |volume=43 |issue=3 |pages=129–136 |doi=10.1111/j.1440-1835.1995.tb00016.x |url=https://doi.org/10.1111/j.1440-1835.1995.tb00016.x |access-date=5 December 2025 |language=en |issn=1440-1835|url-access=subscription }}</ref> may have participate in the process.
== Species == *''Heterocapsa arctica'' {{small|Horiguchi, 1997}} *''Heterocapsa bohaiensis'' {{small|J.Xiao & Y.Li, 2018}} *''Heterocapsa chattonii'' {{small|(Biecheler) P.H.Campbell, 1973}} *''Heterocapsa circularisquama'' {{small|Horiguchi, 1995}} *''Heterocapsa horiguchii'' {{small|Iwataki, Takayama & Matsuoka, 2002}} *''Heterocapsa illdefina'' {{small|(Herman & Sweeney) Morrill & Loeblich III, 1981}} *''Heterocapsa kollmeriana'' {{small|M.J.Swift & McLaughlin, 1970}} *''Heterocapsa lanceolata'' {{small|Iwataki & Fukuyo, 2002}} *''Heterocapsa minima'' {{small|A.J.Pomroy, 1989}} *''Heterocapsa niei'' {{small|(Loeblich III) Morrill & Loeblich III, 1981}} *''Heterocapsa orientalis'' {{small|Iwataki, Botes & Fukuyo, 2003}} *''Heterocapsa ovata'' {{small|Iwataki & Fukuyo, 2003}} *''Heterocapsa pacifica'' {{small|Kofoid, 1907}} *''Heterocapsa psammophila'' {{small|M.Tamura, M.Iwataki & M.Horiguchi, 2006}} *''Heterocapsa pseudotriquetra'' {{small|Iwataki, G.Hansen & Fukuyo, 2002}} *''Heterocapsa pygmaea'' {{small|Lobelich III, R.J.Schmidt & Sherley, 1981}} *''Heterocapsa rotundata'' {{small|(Lohmann) Gert Hansen, 1995}} *''Heterocapsa steinii'' {{small|Tillmann, Gottschling, Hoppenrath, Kusber & Elbrächter, 2017}} *''Heterocapsa umbilicata'' {{small|Stein, 1883}} <ref name="GBIF2" />
==References== {{Reflist}}
{{Taxonbar|from1=Q19751739|from2=Q19751751}}
Category:Dinophyceae Category:Dinoflagellate genera