Calydiscoides | |
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Calydiscoides euzeti | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Platyhelminthes |
Class: | Monogenea |
Order: | Dactylogyridea |
Family: | Diplectanidae |
Genus: | Calydiscoides Young, 1969 |
Species | |
See text |
Calydiscoides is a genus of monopisthocotylean monogeneans, included in the family Diplectanidae. [1]
The genus currently includes 16 species, which are all parasitic on the gills of marine fish of the family Lethrinidae and Nemipteridae. [1] [2] All species are from the Indo-Pacific Ocean. The type-species of the genus is Calydiscoides australis Young, 1969. [3]
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, a main elongate body and a posterior haptor. The digestive system includes an anterior muscular pharynx, and two lateral intestinal branches (or caeca); as in all Platyhelminthes, there is no anus. The haptor, in the posterior part of the body, is a specialized organ used to attach to the 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 squamodiscs (one ventral and one dorsal).
The squamodiscs of species of Calydiscoides are special: they are lamellodiscs , 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. [2] Generally, central lamellae are circles, but peripheral lamellae may be circles or semicircles.
Adults are hermaphroditic. The reproductive organ include a single ovary and a single testis. As in all diplectanids, the ovary (or germarium) is anterior to the testis and loops around the right intestinal caecum. Species of Calydiscoides are characterized by a sclerotized male copulatory organ, which is used in systematics to differentiate species.
The characteristics of the lamellodisc, without paired elements, is the main character which differentiate Calydiscoides from other genera of the family Diplectanidae. Relationships of CalydiscoidesYoung, 1969 with Protolamellodiscus Oliver, 1969 are not clear; the two genera were described almost simultaneously, and it might be that they are synonym. [2] [4]
Hosts of species of Calydiscoides are only members of the families Nemipteridae (threadfin breams) and Lethrinidae (emperors). These families are restricted to the Indo-Pacific Ocean. Lethrinids known to harbour Calydiscoides species include Lethrinus miniatus , Lethrinus nebulosus and Lethrinus atkinsoni ; [2] nemipterids include Nemipterus japonicus , Scolopsis temporalis , Scolopsis monogramma , Scolopsis margaritifera and Pentapodus aureofasciatus . [5] [6] In all cases, species of Calydiscoides were only found on the gills of the fish.
List according to the World Register of Marine Species [7]
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Pseudorhabdosynochus is a genus of monopisthocotylean monogeneans, included in the family Diplectanidae. The type-species of the genus is Pseudorhabdosynochus epinepheli .
The Diplectanidae are a family of monopisthocotylean monogeneans. They are all parasitic on the gills of fish. Diplectanids are small animals, generally around 1 mm in length. As parasites, they can be extremely numerous, up to several thousand on an individual fish.
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 are usually made up of scales embedded in the epidermis, which appear from the outside as rodlets arranged in rows.
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. Lamellodiscs are made up of concentric lamellae embedded in the epidermis. Lamellodiscs are considered as special type of squamodiscs, which are homologous structure found in many diplectanid monogeneans but formed of rows of rodlets instead of lamellae.
Pseudorhabdosynochus huitoe is a diplectanid monogenean parasitic on the gills of the highfin grouper, Epinephelus maculatus. It was described in 2007.
Pseudorhabdosynochus caledonicus is a diplectanid monogenean parasitic on the gills of the Blacktip grouper, Epinephelus fasciatus. It has been described in 2005.
Lamellodiscus is a genus of monopisthocotylean monogeneans in the family Diplectanidae; all species of Lamellodiscus are small worms, parasitic on the gills of teleost fish.
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Pseudorhabdosynochus cyathus is a diplectanid monogenean parasitic on the gills of the grouper Epinephelus howlandi. It has been described in 2006.
Pseudorhabdosynochus oliveri is a diplectanid monogenean parasitic on the gills of the dusky grouper.
Pseudorhabdosynochus justinei is a species of diplectanid monogenean that is parasitic on the gills of the longfin grouper Epinephelus quoyanus. It was described in 2007 by Binjian Zeng and Tingbao Yang from material from the South China Sea, and redescribed in 2009 by Justine, Dupoux & Cribb from material from off Queensland, Australia.
Pseudorhabdosynochus jeanloui is a diplectanid monogenean parasitic on the gills of the Pacific creolefish, Paranthias colonus. It has been described in 2015 by Knoff, Cohen, Cárdenas, Cárdenas-Callirgos & Gomes.
Pseudorhabdosynochus exoticus is a species of diplectanid monogenean that is parasitic on the gills of the blue grouper Epinephelus cyanopodus. It was described in 2008.
Pseudorhabdosynochus cupatus is a species of diplectanid monogenean parasitic on the gills of groupers.
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Pseudorhabdosynochus hargisi is species of a diplectanid monogenean parasitic on the gills of the White grouper Epinephelus aeneus. It was described in 1984 as Diplectanum hargisi and transferred to the genus Pseudorhabdosynochus by Santos, Buchmann & Gibson in 2000. Its systematic position has been clarified by Kritsky, Bakenhaster & Adams in 2015, who differentiated it from Pseudorhabdosynochus americanus.
Pseudorhabdosynochus magnisquamodiscum is species of diplectanid monogenean parasitic on the gills of a fish. It was described in 1984 under the name Cycloplectanum magnisquamodiscum and later transferred to the genus Pseudorhabdosynochus.
Pseudorhabdosynochus summanae is a species of diplectanid monogenean parasitic on the gills of the grouper Epinephelus summana. It was described in 1969, from only four specimens, under the name Diplectanum summanae and transferred to the genus Pseudorhabdosynochus in 1986.
Pseudorhabdosynochus vagampullum is a species of diplectanid monogenean parasitic on the gills of a grouper. It was described in 1969, from eight specimens, under the name Diplectanum vagampullum and transferred to the genus Pseudorhabdosynochus in 1986. The species has been redescribed several times.
Rhabdosynochus is a genus of monopisthocotylean monogeneans, belonging to the family Diplectanidae.