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

gill A gill () is a respiratory organ that many 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 respiration on land provided they are ...

s of species of

grouper Groupers are fish of any of a number of genera in the subfamily Epinephelinae of the family Serranidae, in the order Perciformes. Not all serranids are called "groupers"; the family also includes the sea basses. The common name "grouper" is ...

s. It is the

type species In 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 species that contains the biological type specime ...

of the genus '' Pseudorhabdosynochus'' Yamaguti, 1958.

Description

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

hermaphroditic In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes. Many taxonomic groups of animals (mostly invertebrates) do not have s ...

. 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 differe ...

, 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. Squamodisc ...

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 '' Pseudorhabdosynochus''. The

vagina In mammals, the vagina is the elastic, muscular part of the female genital tract. In humans, it extends from the vestibule to the cervix. The outer vaginal opening is normally partly covered by a thin layer of mucosal tissue called the hymen ...

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
ArticlePDF
(as ''Pseudorhabdosynochus epinepheli'' Yamaguti, 1958). In both papers, the species was described from parasites collected from the same fish species, the grouper '' Epinephelus akaara'' off Japan.
According to Kritsky & 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
PDF
, ''Pseudorhabdosynochus epinepheli'' Yamaguti, 1958 is a junior synonym of ''Pseudorhabdosynochus epinepheli'' (Yamaguti, 1938) Kritsky & 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 in Paris, France, and a specialist of fish parasites and invasive land planarians. Higher education and career Justine w ...

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 '' Epinephelus akaara'' and the type-locality if off Japan. The species has also been redescribed from the brown spotted reef cod '' Epinephelus chlorostigma'' off New Caledonia, 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 ''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 Fauna of New Caledonia Fauna of China Taxa named by Satyu Yamaguti