{{short description|Species of worms}} {{Speciesbox | image = Goto 1894 - Studies on the Ectoparasitic Trematodes of Japan - Plate 1 - Microcotyle sebastis.png | image_caption = ''Microcotyle sebastis'', drawing from original description | genus = Microcotyle | species = sebastis | authority = Goto, 1894 <ref name="Goto1894"/> | synonyms = }}
'''''Microcotyle sebastis''''' is a species of monogenean, parasitic on the gills of a marine fish. It belongs to the family Microcotylidae.<ref name="Goto1894">{{cite journal|last1=Goto|first1=Seitaro.|title=Studies on the ectoparasitic Trematodes of Japan|year=1894|doi=10.5962/bhl.title.56506|doi-access=free}} {{open acess}}</ref>
==Studies dealing with ''Microcotyle sebastis''== ''Microcotyle sebastis'' was first described by Goto in 1894, based on specimens obtained from the gills of rockfish, ''Sebastes'' sp.<ref name="Goto1894"/> In the original description, the author also illustrated the various stages of spermatogenesis of the species.<ref name="Goto1894"/> Bychowsky (1957) provided a brief description of the oncomiracidium; his study was completed by Thoney who described the post-larval growth and morphological changes during development.<ref name="Thoney1986"/> It has been subsequently recorded on several host species, mostly from the genus ''Sebastes''.<ref name="Thoney1986"/> Bonham & Guberlet (1937) redescribed this species based on ten mature specimens from ''Sebastodes'' spp collected from Puget Sound, United States.<ref name="BonhamGuberlet1937">{{cite journal|last1=Bonham|first1=Kelshaw|last2=Guberlet|first2=John E.|title=Notes on ''Microcotyle sebastis'' Goto from Puget Sound|journal=Journal of Parasitology|volume=23|issue=3|year=1937|pages=281|issn=0022-3395|doi=10.2307/3272417|jstor=3272417|doi-access=free}}</ref>
Yamaguti redescribed ''Microcotyle sebastis'' based on two specimens from the gills of ''Sebastes schlegelii'' from Mutsu Bay, Japan.<ref>{{cite journal |last1=Yamaguti |first1=S. |title=Studies on the helminth fauna of Japan. Part II. Trematodes of fishes, I |journal=Japanese Journal of Zoology |date=1934 |volume=5 |issue=3 |pages=249–541 |id={{NAID|10027668348}} }}</ref> Yamaguti noted that the framework of the posterior clamps differed from Goto's representation, and that his specimens had lateral branches from the oesophagus, not mentioned by Goto. Bonham & Guberlet noted that their specimens were rather intermediate in both characters.<ref name="BonhamGuberlet1937"/> Yoon et al. studied the seasonality and the microhabitat of ''Microcotyle sebastis'' from the gills of farmed ''Sebastes schlegeli''. <ref name="YoonShinnSommervilleJo1997">{{cite journal |last1=Yoon |first1=Gil Ha |last2=Shinn |first2=Andrew |last3=Sommerville |first3=Christina |last4=Jo |first4=Jae-Yoon |title=Seasonality and the microhabitat of Microcotyle sebastis Goto, 1894, a monogenean gill parasite of farmed rockfish, Sebastes schlegeli Hilgendorf 1880 |journal=Korean Journal of Aquaculture |date=1997 |volume=10 |issue=4 |pages=387–394 |url=https://dspace.stir.ac.uk/handle/1893/10235 }}</ref>
Radujkovic & Euzet reported one specimen of ''M. sebastis'' from the gills of ''Helicolenus dactylopterus''.<ref name="Radujkovic&Euzet1989">Branko M. Radujkovic, Louis Euzet, Parasites des poissons marins du Monténégro: Monogènes, in: B. M. Radujkovic, A. Raibaut (Eds.),Faune des parasites de poissons marins des côtes du Monténégro (Adriatique Sud), Acta Adriatica, 30, 51–135.</ref> Ayadi et al. suggested that the species of ''Microcotyle'' collected from ''Helicolenus dactylopterus'' from off Montenegro and identified as ''M. sebastis'' by Radujkovic & Euzet was probably a different species, based on extremely geographically distant localities (Pacific Ocean vs Mediterranean Sea), absence of detailed morphological evidences of identity, and absence of molecular information.<ref name="AyadiGey2017"/>
Ayadi et al., suggested that species of ''Microcotyle'' from scorpaeniform fish on the Eastern side of the Pacific (USA coast) might be the same as ''M. sebastis'' (for which the type-locality is off Japan) and emphasised the need for a detailed morphological and molecular study of specimens from different localities and hosts.<ref name="AyadiGey2017"/>
==Morphology== ''Microcotyle sebastis'' has the general morphology of all species of ''Microcotyle'', with a slender symmetrical body. The body comprises an anterior part which contains most organs and a posterior part called the haptor. The haptor bears 58 clamps, arranged as two rows (29 on each side). The clamps of the haptor attach the animal to the gill of the fish. There are also two buccal septate suckers at the anterior extremity. The digestive organs include an anterior, terminal mouth, a pharynx, and a posterior intestine with two branches provided with only a few short branches towards the median side, the left branch is longer than the right, and both branches extends for a certain distance into the haptor. Each adult contains male and female reproductive organs. The reproductive organs include a genital atrium opening a little in front of the point of bifurcation of the alimentary canal, armed with conical slightly curved spines, unarmed vagina opening middorsally behind the common genital opening, a single ovary, with an anterior portion shaped as in inversed V and a posterior portion somewhat S-shaped, about 40 small testes posterior to the ovary and occupying a little less than one-fifth the whole length of the body.<ref name="Goto1894"/> Information on the surface topography of ''Microcotyle sebastis'' is available in the study of Alyousif (1986).<ref name="Alyousif M.S., 1986.">Alyousif M.S., 1986. Surface topography of ''Microcotyle sebastis'' (Trematoda Monogenea) by scanning électron microscopy. Annals of Zoology (Agra), 24, 1-18.</ref>
==Post-larval growth== During post-larval development of ''Microcotyle sebastis'', the ciliated epidermal jacket, ocellus, and larval opisthaptor are lost, and the clamps and genitalia develop. ''Microcotyle sebastis'' is protandrous and the genital elements develop in a specific order, following that of ''M. mormyri''.<ref name="Thoney1986"/> The larval ciliated epidermal jacket and the four pairs of lateral hooks were shed by the "2 clamp-pair stage". The other hooks remain on the haptor and are lost between the 3 and 5 clamp-pair stage. As the clamps are then added, the genitalia develop and the intestinal branches extend. The 20 clamp-pair stage is reached within 12 days after hatching.<ref name="Thoney1986">{{cite journal|last1=Thoney|first1=Dennis A.|title=Post-Larval Growth of ''Microcotyle sebastis'' (Platyhelminthes: Monogenea), a Gill Parasite of the Black Rockfish|journal=Transactions of the American Microscopical Society|volume=105|issue=2|year=1986|pages=170–181|issn=0003-0023|doi=10.2307/3226389|jstor=3226389}}</ref>
==Etymology== The specific epithet ''sebastis'' is derived from the generic name of the type-host ''Sebastes'' sp.<ref name="Goto1894"/>
==Molecular information== Park et al. provided the complete mitochondrial genome of ''Microcotyle sebastis'', which is 14,407 bp in size, and considered one of the largest flatworm mitochondrial genomes published<ref name="Parketal2007">{{cite journal |last1=Park |first1=Joong-Ki |last2=Kim |first2=Kyu-Heon |last3=Kang |first3=Seokha |last4=Kim |first4=Won |last5=Eom |first5=Keeseon S |last6=Littlewood |first6=DTJ |title=A common origin of complex life cycles in parasitic flatworms: evidence from the complete mitochondrial genome of Microcotyle sebastis (Monogenea: Platyhelminthes) |journal=BMC Evolutionary Biology |date=2 February 2007 |volume=7 |pages=11 |doi=10.1186/1471-2148-7-11 |pmid=17270057 |pmc=1800851 |doi-access=free }}</ref> However, Ayadi et al. pointed that Park et al. did not indicate any deposition of material in a Museum collection.<ref name="AyadiGey2017">{{cite journal|last1=Ayadi|first1=Zouhour El Mouna|last2=Gey|first2=Delphine|last3=Justine|first3=Jean-Lou|last4=Tazerouti|first4=Fadila|title=A new species of ''Microcotyle'' (Monogenea: Microcotylidae) from ''Scorpaena notata'' (Teleostei: Scorpaenidae) in the Mediterranean Sea|journal=Parasitology International|volume=66|issue=2|year=2017|pages=37–42|issn=1383-5769|doi=10.1016/j.parint.2016.11.004|pmid=27840197|url=http://hal.upmc.fr/hal-01462207/file/El_Mouna_Ayadi_A_new_species_of.pdf}}</ref>
==Hosts and localities== [[File:Sebastes schlegelii Hilgendorf, 1880.jpg|thumb|left|The Korean rockfish ''Sebastes schelegelii'' is reported as host of ''Microcotyle sebastis'']] [[File:Sebastes melanops.jpg|thumb|left|The black rockfish''Sebastes melanops'' is also recorded as host of ''Microcotyle sebastis'']] [[File:Sebastes caurinus 1.jpg|thumb|left|The Copper rockfish ''Sebastes caurinus'' is another Sebastidae recorded as host of ''Microcotyle sebastis'']] [[File:Quillback Rockfish Alaska Sealife Center.JPG|thumb|left|''Sebastes maliger'', also known as Quillback Rockfish, is reported as host of ''Microcotyle sebastis'' as well]] [[File:Sebastes flavidus.jpg|thumb|left|The yellowtail rockfish ''Sebastes flavidus'', another Sebastidae reported as host of ''Microcotyle sebastis'']] [[File:Helicolenus dactylopterus dactylopterus.jpg|thumb|left|The Blackbelly rosefish ''Helicolenus dactylopterus'', host of ''Microcotyle sebastis'']] The type-host is ''Sebastes'' sp.<ref name="Goto1894"/> ''Microcotyle sebastis'' was also reported on several (Sebastidae); the Korean rockfish ''Sebastes schelegelii'',<ref name="KimChoi1998"/><ref name="KimCho2000"/><ref name="Kimetal1998"/> on the black rockfish ''Sebastes melanops'',<ref name="Thoney1986"/> ''Sebastodes caurinus'' ( currently synonymised with the Copper rockfish ''Sebastes caurinus''), ''Sebastodes maliger'' ( currently synonymised with the Quillback Rockfish ''Sebastes maliger'') <ref name="BonhamGuberlet1937"/> ''Sebastes oblongus'' <ref name="Machida1972">Machida, M., Araki, J., Kamiya, H. and Ohbayashi, M. (1972). Trematodes collected from sea fishes of the Hidaka District, Hokkaido. Memoirs of the National Science Museum 5: 1–9. [In Japanese with English abstract])</ref> the Blackbelly rosefish ''Helicolenus dactylopterus'',<ref name="Radujkovic&Euzet1989"/><ref name="Gajevskaja&Aljoshkina1988">A.V. Gajevskaja, L.D. Aljoshkina, Fauna of monogenea of the south-east Atlantic, its ecological and geographical analysis, Zool. Zhurnal. 57 (3) (1988) 325–330Moscow.</ref> and on the yellowtail rockfish ''Sebastes flavidus''.<ref name="StanleyLee1992">{{cite journal|last1=Stanley|first1=R. D.|last2=Lee|first2=D. L.|last3=Whitaker|first3=D. J.|title=Parasites of yellowtail rockfish, ''Sebastes flavidus'' (Ayres, 1862) (Pisces: Teleostei), from the Pacific coast of North America as potential biological tags for stock identification|journal=Canadian Journal of Zoology|volume=70|issue=6|year=1992|pages=1086–1096|issn=0008-4301|doi=10.1139/z92-152}}</ref>
''Microcotyle sebastis'' was first described from fishes caught off Hakodate off Japan.<ref name="Goto1894"/> It was also reported from farms in Korea,<ref name="KimChoi1998"/><ref name="KimCho2000"/><ref name="YoonShinnSommervilleJo1997"/><ref name="Kimetal1998"/><ref name="Parketal2007"/> off California,<ref name="Thoney1986"/> Puget Sound,<ref name="BonhamGuberlet1937"/> off Japan,<ref name="Machida1972"/> off Montenegro,<ref name="Radujkovic&Euzet1989"/> Southeast Atlantic,<ref name="Gajevskaja&Aljoshkina1988"/> and from the Pacific coast of North America.<ref name="StanleyLee1992"/>
Note that Tongyoung is considered an endemic area of ''M. sebastis''.<ref name="KimChoi1998"/> When Stanley & Lee investigated parasites of yellowtail rockfish, ''Sebastes flavidus''from the Pacific coast of North America as potential biological tags for stock identification, they revealed that only ''Microcotyle sebastis'' showed a latitudinal cline with a prevalence increasing from 0- 10% in samples from central British Columbia, to 80 and 100% in those off and Oregon respectively.<ref name="StanleyLee1992"/>
==Pathology of fish and treatment== ''Microcotyle sebastis'' is a major parasitic disease agent for ''Sebastes schlegeli'' in Korea, responsible for a high mortality rate of juveniles in Summer.<ref name="KimChoi1998"/><ref name="KimCho2000"/><ref name="YoonShinnSommervilleJo1997"/>
Ki Hong Kim & Eun Seok Choi evaluated the oral administration of mebendazole or bithionol for the control of ''Microcotyle sebastis'' and suggested that a single dose of 50 mg mebendazole/kg B.W., 100 mg bithionol/kg B.W. or 200 mg bithionol/kg B.W. significantly reduces the numbers of this monogenean on the gills of the host fish.<ref name="KimChoi1998">{{cite journal|last1=Kim|first1=Ki Hong|last2=Choi|first2=Eun Seok|title=Treatment of Microcotyle sebastis (Monogenea) on the gills of cultured rockfish (''Sebastes schelegeli'') with oral administration of mebendazole and bithionol|journal=Aquaculture|volume=167|issue=1–2|year=1998|pages=115–121|issn=0044-8486|doi=10.1016/S0044-8486(98)00300-7|bibcode=1998Aquac.167..115K }}</ref>
Kim & Cho also suggested that feeding a praziquantel-adsorbed diet significantly reduces the abundance of ''M. sebastis'' infestation, and that bathing in 100 ppm praziquantel for 4 min is effective for controlling infestations in practical rockfish cultures.<ref name="KimCho2000">{{cite journal|last1=Kim|first1=KH|last2=Cho|first2=JB|title=Treatment of ''Microcotyle sebastis'' (Monogenea: Polyopisthocotylea) infestation with praziquantel in an experimental cage simulating commercial rockfish ''Sebastes schlegeli'' culture conditions|journal=Diseases of Aquatic Organisms|volume=40|issue=3|year=2000|pages=229–231|issn=0177-5103|doi=10.3354/dao040229|pmid=10843562|doi-access=free}}</ref> Kim et al. investigated the influence of the temperature on the rate of egg production and on the embryonic development of ''Microcotyle sebastis'' to determine the precise time of a second treatment.<ref name="Kimetal1998">Kim, K. H., Choi, E. S., Cho, J. B., Hwang, Y. J., & Park, S. I. (1998). Influence of temperature on the egg production and hatching of ''Microcotyle sebastis'' (Monogenea: Microcotylidae), parasitic on Rockfish, ''Sebastes schlegeli''. Journal of Fish Pathology, 11(2), 113-117. [http://kosficfile.jnu.ac.kr/korea_journal/105120/105120-011-0002-004.pdf PDF] {{open acess}}</ref> It was suggested that treatment of ''M. sebastis'' with medicated feed was more practical than bath treatment in netpen farms. However, the authors noted that these chemicals should be administered to only juveniles until pharmacokinetic characteristics of these compounds in fish are investigated.<ref name="KimChoi1998"/>
==References== {{Reflist}}
{{Taxonbar|from=Q2497104|knsl=yes}}
Category:Microcotyle Category:Parasites of fish Category:Animals described in 1894 Category:Fauna of Japan Category:Fauna of South Korea