''Calydiscoides'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

monopisthocotylea The Monopisthocotylea are a subclass of parasitic flatworms in the class Monogenea. WoRMS (2019). Monopisthocotylea. Accessed at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=119219 on 2019-02-08 Yamaguti, S. (1963). Systema Helminthum V ...

monogenea Monogeneans are a group of ectoparasitic flatworms commonly found on the skin, gills, or fins of fish. They have a direct lifecycle and do not require an intermediate host. Adults are hermaphrodites, meaning they have both male and female reprod ...

ns, included in the family

Diplectanidae The Diplectanidae are a family of monopisthocotylean monogeneans. They are all parasitic on the gills of fish (marine or freshwater). Diplectanids are small animals, generally around 1 mm in length. As parasites, they can be extremely numerou ...

. The genus currently includes 16

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

, which are all 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 ar ...

s of marine fish of the family Lethrinidae and

Nemipteridae Nemipteridae are a family of fishes within the order Perciformes. They are known as threadfin breams, whiptail breams and false snappers. They are found in tropical waters of the Indian and western Pacific Oceans. Most species are benthic carni ...

. All species are from the

Indo-Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...

Ocean. The type-species of the genus is '' Calydiscoides australis'' Young, 1969.

Morphology

Lamellodisc of Calydiscoides euzeti (Monogenea, Diplectanidae)

All species of ''Calydiscoides'' are small animals, ranging 0.5–1 mm in length. As with most monogeneans, they are flat, with an anterior head bearing four oculi and head

glands In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormones) for release into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland). Structure De ...

, a main elongate 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 differ ...

. The digestive system includes an anterior muscular

pharynx The pharynx (plural: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the oesophagus and trachea (the tubes going down to the stomach and the lungs). It is found in vertebrates and invertebrates, though its ...

, and two lateral intestinal branches (or caeca); as in all

Platyhelminthes The flatworms, flat worms, Platyhelminthes, or platyhelminths (from the Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") are a phylum of relatively simple bilaterian, unsegment ...

, there is no anus. The

, in the posterior part of the body, is a specialized organ used to attach to the

host A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places *Host, Pennsylvania, a village in Berks County People * Jim Host (born 1937), American businessman * Michel Host ...

. The haptor includes sclerotized elements, namely a ventral bar, two lateral (dorsal) bars, two ventral hooks, and two dorsal hooks, and fourteen hooklets. As in most diplectanids, the haptor bears characteristic, structures called

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). The squamodiscs of species of ''Calydiscoides'' are special: they are

lamellodisc Lamellodiscs are epidermal structures, which are typical of and found only in certain monogeneans of the family Diplectanidae. There are, typically, two lamellodiscs, one ventral and one dorsal, located on the haptor of the monogenean. Lamellodis ...

s, which are made up of concentric lamellae, not separate rodlets as in regular squamodiscs. The diameter of the lamellodiscs range 25–60 µm. When observed from its concentric axis (ventral or dorsal observation of the specimen, ‘polar’ view of the lamellodisc), the lamellodisc appears as concentric circles. Generally, central lamellae are circles, but peripheral lamellae may be circles or semicircles. 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 se ...

. The reproductive organ include a single

ovary The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the bod ...

and a single

testis A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testoster ...

. As in all diplectanids, the

(or germarium) is anterior to the

and loops around the right intestinal caecum. Species of ''Calydiscoides'' are characterized by a sclerotized male copulatory organ, which is used in

systematics Biological systematics is the study of the diversification of living forms, both past and present, and the relationships among living things through time. Relationships are visualized as evolutionary trees (synonyms: cladograms, phylogenetic t ...

to differentiate species.

Systematics

The characteristics of the lamellodisc, without paired elements, is the main character which differentiate ''Calydiscoides'' from other

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial ...

of the family Diplectanidae. Relationships of ''Calydiscoides'' Young, 1969 with ''

Protolamellodiscus ''Protolamellodiscus'' is a genus of monopisthocotylean monogeneans in the family Diplectanidae.Oliver G., 1969. Recherches sur les Diplectanidae (Monogenea) parasites de Téléostéens du Golfe du Lion. II. Lamellodiscinae nov. sub-fam. Vie & ...

'' Oliver, 1969 are not clear; the two genera were described almost simultaneously, and it might be that they are synonym.

Hosts

Hosts of species of ''Calydiscoides'' are only members of the families

(Threadfin breams) and Lethrinidae (Emperors). These families are restricted to the

Ocean. Lethrinids known to harbour ''Calydiscoides'' species include ''

Lethrinus miniatus ''Lethrinus miniatus'', the sweetlip emperor, sweetlip swoose or trumpet emperor, is a fish of the family Lethrinidae. It can be found on coral reefs and moderately warm waters in the Western Pacific Ocean, although its primary habitat is the ...

'', '' Lethrinus nebulosus'' and '' Lethrinus atkinsoni''; nemipterids include ''

Nemipterus japonicus ''Nemipterus japonicus'', commonly known as the Japanese threadfin bream, is a marine fish native to the Pacific and Indian Oceans. The species now also occurs in the Mediterranean, having invaded as a Lessepsian migrant through the Suez Canal. I ...

'', ''

Scolopsis temporalis ''Scolopsis'' is a genus of threadfin breams native to the Indian Ocean and the western Pacific Ocean. Species The currently recognized species in this genus are: * ''Scolopsis affinis'' W. K. H. Peters, 1877 (Peters' monocle bream) * ''Sco ...

'', '' Scolopsis monogramma'', '' Scolopsis margaritifera'' and '' Pentapodus aureofasciatus''. In all cases, species of ''Calydiscoides'' were only found on the

gills 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 ...

of the fish.

List of species

List according to the World Register of Marine Species *'' Calydiscoides australis'' Young, 1969 *''

Calydiscoides conus ''Calydiscoides'' is a genus of monopisthocotylean monogeneans, included in the family Diplectanidae. The genus currently includes 16 species, which are all parasitic on the gills of marine fish of the family Lethrinidae and Nemipteridae. A ...

'' Lim, 2003 *'' Calydiscoides cymbidioides'' Ding & Zhang, 1996 *''

Calydiscoides difficilis ''Calydiscoides'' is a genus of monopisthocotylean monogeneans, included in the family Diplectanidae. The genus currently includes 16 species, which are all parasitic on the gills of marine fish of the family Lethrinidae and Nemipteridae. All ...

'' ( Yamaguti, 1953) Young, 1969 Yamaguti, S. 1953: Parasitic worms mainly from Celebes. Part 2. Monogenetic trematodes of fishes. Acta Medicinae Okayama, 8, 203-256 + 209 Pl
ArticlePDF
*''

Calydiscoides duplicostatus ''Calydiscoides'' is a genus of monopisthocotylean monogeneans, included in the family Diplectanidae. The genus currently includes 16 species, which are all parasitic on the gills of marine fish of the family Lethrinidae and Nemipteridae. All ...

'' ( Yamaguti, 1953) Young, 1969 *''

Calydiscoides euzeti ''Calydiscoides euzeti'' is a species of monogenean of the family Diplectanidae. As all members of the family Diplectanidae, it has a single posterior testis and a single ovary that wraps the lateral caecum of the intestine. As all members ...

'' Justine, 2007 *''

Calydiscoides flexuosus ''Calydiscoides'' is a genus of monopisthocotylean monogeneans, included in the family Diplectanidae. The genus currently includes 16 species, which are all parasitic on the gills of marine fish of the family Lethrinidae and Nemipteridae. A ...

'' ( Yamaguti, 1953) Young, 1969 *'' Calydiscoides gussevi'' Oliver, 1984 *''

Calydiscoides japonicus ''Calydiscoides'' is a genus of monopisthocotylean monogeneans, included in the family Diplectanidae. The genus currently includes 16 species, which are all parasitic on the gills of marine fish of the family Lethrinidae and Nemipteridae. A ...

'' (Pillai & Pillai, 1976) Thoney, 1989 *'' Calydiscoides kemamanensis'' Lim, 2003 *''

Calydiscoides limae ''Calydiscoides'' is a genus of monopisthocotylean monogeneans, included in the family Diplectanidae. The genus currently includes 16 species, which are all parasitic on the gills of marine fish of the family Lethrinidae and Nemipteridae. A ...

'' Justine & Brena, 2009 *'' Calydiscoides monogrammae'' Lim, 2003 *''

Calydiscoides nemipteris ''Calydiscoides'' is a genus of monopisthocotylean monogeneans, included in the family Diplectanidae. The genus currently includes 16 species, which are all parasitic on the gills of marine fish of the family Lethrinidae and Nemipteridae. All sp ...

'' Thoney, 1989 *'' Calydiscoides rohdei'' Oliver, 1984 *''

Calydiscoides scolopsidis ''Calydiscoides'' is a genus of monopisthocotylean monogeneans, included in the family Diplectanidae. The genus currently includes 16 species, which are all parasitic on the gills of marine fish of the family Lethrinidae and Nemipteridae. ...

'' Lim, 2003 *''

Calydiscoides terpsichore ''Calydiscoides'' is a genus of monopisthocotylean monogeneans, included in the family Diplectanidae. The genus currently includes 16 species, which are all parasitic on the gills of marine fish of the family Lethrinidae and Nemipteridae. ...

'' Rascalou & Justine, 2007

References

External links

{{Taxonbar, from=Q18579589 Monopisthocotylea Monogenea genera Diplectanidae