''Pseudorhabdosynochus epinepheli'' is a diplectanid monogenean parasitic on the

gill A gill () is a respiration organ, respiratory organ that many aquatic ecosystem, aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow r ...

s of species of

grouper Groupers are a diverse group of marine ray-finned fish in the family Epinephelidae, in the order Perciformes. Groupers were long considered a subfamily of the seabasses in Serranidae, but are now treated as distinct. Not all members of this f ...

s. It is the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

of the genus ''

Pseudorhabdosynochus ''Pseudorhabdosynochus'' is a genus of monopisthocotylean monogeneans, included in the family Diplectanidae. The type-species of the genus is ''Pseudorhabdosynochus epinepheli'' ( Yamaguti, 1938). The genus includes more than 80 species, which a ...

'' Yamaguti, 1958.

Description

''Pseudorhabdosynochus epinepheli'' is a small monogenean, about half a millimetre in length. Adults are

hermaphroditic A hermaphrodite () is a sexually reproducing organism that produces both male and female gametes. Animal species in which individuals are either male or female are gonochoric, which is the opposite of hermaphroditic. The individuals of many ...

. The species has the general characteristics of other diplectanids, with a flat body and a posterior

haptor The haptor is the attachment organ of the monogeneans, a group of parasitic Platyhelminthes. The haptor is sometimes called opisthaptor (from ''opistho-'': behind) to emphasize that it is located in the posterior part of the body, and to diffe ...

, which is the organ by which the monogenean attaches itself to the gill of is host. The haptor bears two

squamodisc Squamodiscs are epidermal structures, which are typical of and found only in certain monogeneans of the family Diplectanidae. There are, typically, two squamodiscs, one ventral and one dorsal, located on the haptor of the monogenean. Squamodiscs ...

s, one ventral and one dorsal, which are made up of numerous rows of rodlets. The reproductive organ include a single ovary and a single testis. The sclerotized male copulatory organ, or "quadriloculate organ", has the shape of a bean with four internal chambers, as in other species of ''

''. The

vagina In mammals and other animals, the vagina (: vaginas or vaginae) is the elastic, muscular sex organ, reproductive organ of the female genital tract. In humans, it extends from the vulval vestibule to the cervix (neck of the uterus). The #Vag ...

also includes a sclerotized part, which is a complex structure. The sclerotised vagina comprises an anterior trumpet, followed by a primary canal, a primary chamber, a secondary canal, a secondary chamber and an accessory structure. The trumpet is in continuity with the unsclerotised vagina. The primary canal is thin-walled, with regular diameter and wide lumen, and is coiled once. The primary chamber is heavily sclerotised, and complex in shape: a pear-shaped cavity continued as a heavily sclerotised cylinder arising from its thinner, posterior part; the cylinder curves and runs parallel with the longitudinal axis of the pear-shaped cavity; the cylinder continuous with primary canal. The secondary canal is thin, with an indistinct central lumen. The secondary canal is inserted into the cylinder of the primary chamber. The secondary chamber is continuous with the secondary canal, sclerotised, and elongate, ventral to and much smaller than the primary chamber. The accessory structure is small, inserted into the anterior extremity of the secondary chamber. The external and internal surfaces of the primary and secondary chambers are smooth.

Nomenclature and synonyms

The famous Japanese parasitologist

Satyu Yamaguti was a Japanese parasitologist, entomologist, and helminthologist. He was a specialist of mosquitoes and helminths such as digeneans, monogeneans, cestodes, acanthocephalans and nematodes. He also worked on the parasitic crustaceans Copepoda and ...

described the same species twice, the first time in 1938 Yamaguti, S. 1938: Studies on the helminth fauna of Japan. Part 24. Trematodes of fishes, V. Japanese Journal of Zoology, 8, 15-74. (as ''Diplectanum epinepheli'' Yamaguti, 1938) and the second time in 1958 Yamaguti, S. 1958: Studies on the helminth fauna of Japan. Part 53. Trematodes of fishes, XII. Publications of the Seto Marine Biological Laboratory, 7, 53-88
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(as ''Pseudorhabdosynochus epinepheli'' Yamaguti, 1958). In both papers, the species was described from parasites collected from the same fish species, the grouper ''

Epinephelus akaara The Hong Kong grouper (''Epinephelus akaara'') is a species of marine ray-finned fish, a grouper from the subfamily Epinephelinae which is part of the family Serranidae, which also includes the anthias and sea basses. It is found in eastern and ...

'' off

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

.
According to

Kritsky ''Kritsky'' is a genus of digeneans in the family Aporocotylidae or blood flukes.WoRMS (2018). Kritsky Orelis-Ribeiro & Bullard, 2016. Accessed at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=871002 on 2018-09-23 The name of the genus ...

& Beverley-Burton (1986) Kritsky, D. C. & Beverley-Burton, M. 1986: The status of ''Pseudorhabdosynochus'' Yamaguti, 1958, and ''Cycloplectanum'' Oliver, 1968 (Monogenea: Diplectanidae). ''Proceedings of the Biological Society of Washington'', 99, 17-20
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, ''Pseudorhabdosynochus epinepheli'' Yamaguti, 1958 is a junior synonym of ''Pseudorhabdosynochus epinepheli'' (Yamaguti, 1938)

& Beverley-Burton, 1986 and ''Pseudorhabdosynochus epinepheli'' (Yamaguti, 1938) Kritsky & Beverley-Burton, 1986 is the modern valid combination for ''Diplectanum epinepheli'' Yamaguti, 1938. Re-examination of type-specimens by

Jean-Lou Justine Jean-Lou Justine (born 1955), French parasitologist and zoologist, is a professor at the National Museum of Natural History (France), National Museum of Natural History in Paris, France, and a specialist of fish parasites and invasive species, inv ...

have confirmed this interpretation.
Other synonyms include ''Cycloplectanum americanum'' (Price, 1937) Oliver, 1968, ''partim''; ''Cycloplectanum hongkongensis'' Beverley-Burton & Suriano, 1981; ''Cycloplectanum epinepheli'' (Yamaguti, 1938) Beverley-Burton & Suriano, 1981; ''Cycloplectanum yamagutii'' Beverley-Burton & Suriano, 1981; ''Cycloplectanum yamagutti'' ic; lapsusBeverley-Burton & Suriano, 1981.

Hosts

The type-host of ''Pseudorhabdosynochus epinepheli'' is the grouper ''

'' and the type-locality if off

. The species has also been redescribed from the brown spotted reef cod ''

Epinephelus chlorostigma The brownspotted grouper (''Epinephelus chlorostigma''), also known as the brown spotted reef cod, brown-spotted rockcod, coral grouper or honeycomb cod, is a species of marine ray-finned fish, a grouper from the subfamily Epinephelinae which is ...

'' off

New Caledonia New Caledonia ( ; ) is a group of islands in the southwest Pacific Ocean, southwest of Vanuatu and east of Australia. Located from Metropolitan France, it forms a Overseas France#Sui generis collectivity, ''sui generis'' collectivity of t ...

, and recorded from the orange-spotted grouper ''

Epinephelus coioides The orange-spotted grouper (''Epinephelus coioides''), also known as the brown-spotted rockcod, estuary cod, estuary rockcod, goldspotted rockcod, greasy cod, North-west groper, orange spotted cod or blue-and-yellow grouper, is a species of marin ...

'' off South

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

''P. epinepheli'' has also been recorded from other fish species but these records have been questioned.

References

{{Taxonbar, from=Q5415425 Diplectanidae Animals described in 1938 Fauna of Japan Platyhelminthes of New Caledonia Fauna of China Taxa named by Satyu Yamaguti