''Dermocystidium'' is a genus of cyst-forming,

eukaryotic The eukaryotes ( ) constitute the Domain (biology), domain of Eukaryota or Eukarya, organisms whose Cell (biology), cells have a membrane-bound cell nucleus, nucleus. All animals, plants, Fungus, fungi, seaweeds, and many unicellular organisms ...

fish parasites, the causative agents of dermocystidiosis.

Taxonomic history

The genus ''Dermocystidium'' was described in 1907. It was previously thought to be a genus of fungal parasites, related to the

Thraustochytrida Thraustochytrids are single-celled saprotrophic eukaryotes (decomposers) that are widely distributed in marine ecosystems, and which secrete enzymes including, but not limited to amylases, proteases, phosphatases. They are most abundant in region ...

and

Labyrinthulida Labyrinthulomycetes (ICNafp) or Labyrinthulea (ICZN) is a class of protists that produce a network of filaments or tubes, which serve as tracks for the cells to glide along and absorb nutrients for them. The two main groups are the labyrinthul ...

(both those groups are now considered to be

stramenopile The stramenopiles, also called heterokonts, are protists distinguished by the presence of stiff tripartite external hairs. In most species, the hairs are attached to flagella, in some they are attached to other areas of the cellular surface, an ...

s rather than

fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

). Other biologists considered it to be a

sporozoa The Apicomplexa (also called Apicomplexia; single: apicomplexan) are organisms of a large phylum of mainly parasitic alveolates. Most possess a unique form of organelle structure that comprises a type of non-photosynthetic plastid called an apico ...

n protist. It was subsequently identified as one of a group of fish parasites (the "DRIP clade") of previously uncertain affiliation, which were later identified as nonanimal, nonfungal

opisthokont The opisthokonts () are a broad group of eukaryotes, including both the animal and fungus kingdoms. The opisthokonts, previously called the "Fungi/Metazoa group", are generally recognized as a clade. Opisthokonts together with Apusomonadida and ...

s, and renamed as

Ichthyosporea The Ichthyosporea (or DRIP clade, or Mesomycetozoea) are a small group of Opisthokonta in Eukaryota (formerly protists), mostly parasites of fish and other animals. Significance They are not particularly distinctive morphologically, appearing i ...

, and after expansion as

Mesomycetozoa The Ichthyosporea (or DRIP clade, or Mesomycetozoea) are a small group of Opisthokonta in Eukaryota (formerly protists), mostly parasites of fish and other animals. Significance They are not particularly distinctive morphologically, appearing i ...

. Parasites of crustacea (''Dermocystidium daphniae'') and

mollusc Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

s (''Dermocystidium marinum'') placed in this genus have been found to be likely a

bacterium Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among the ...

and an

alveolate The alveolates (meaning "pitted like a honeycomb") are a group of protists, considered a major unranked clade or superphylum within Eukaryota. They are currently grouped with the Stramenopiles and Rhizaria among the protists with tubulocristate ...

, respectively: Sayre, Gherna and Wergin (1983) concluded that ''Dermocystidium daphniae'' was likely identical to ''

Pasteuria ramosa ''Pasteuria ramosa'' is a gram-positive, endospore-forming bacterium in the Bacillus/Clostridia clade within Bacillota. It is an obligate pathogen of cladoceran crustaceans from the genus ''Daphnia''. ''Daphnia'' is a genus of small planktonic cr ...

'' Metchnikoff, 1888, while ''D. marinum'' has been reclassified as ''

Perkinsus marinus ''Perkinsus marinus'' is a species of alveolate belonging to the phylum Perkinsozoa.Joseph, S., et al. (2010)The alveolate ''Perkinsus marinus'': biological insights from EST gene discovery.''BMC Genomics'' 11(1), 228. It is similar to a dinofl ...

''. The frog parasite ''Dermocystidium ranae'' has been segregated as '' Amphibiocystidium ranae''.

Species

* ''Dermocystidium aegyptiacus'' El-Mansy 2008 * ''Dermocystidium anguillae'' Spangenberg 1975— a gill parasite of eels * ''Dermocystidium branchialis'' Léger 1914Index Fungorum
/ref> — a gill parasite of salmonids * ''Dermocystidium cochliopodii'' Valkanov 1967 * ''Dermocystidium cyprini'' Červinka & Lom 1974 — a gill parasite of carp * ''Dermocystidium erschowii'' Garkavi, Denisov & Afanas'ev 1980— a skin parasite of carp * ''Dermocystidium fennicum'' Pekkarinen et al. 2003— a skin parasite of perch * ''Dermocystidium gasterostei'' Elkan 1962 — a parasite of sticklebacks * ''Dermocystidium granulosum'' Sterba & Naumann 1970 * ''Dermocystidium guyenotii'' Thélin 1955 * ''Dermocystidium koi'' Hoshina & Sahara 1950 — a skin parasite of carp * ''Dermocystidium kwangtungensis'' * ''Dermocystidium macrophagi'' van de Moer, Manier & Bouix 1988 * ''Dermocystidium nemachili'' * ''Dermocystidium penneri'' (Jay & Pohley 1981) Borteiro et al. 2018 * ''Dermocystidium percae'' Reichenbach-Klinke 1950 — a skin parasite of perch * ''Dermocystidium pusulum'' (Pérez 1907) Pérez 1908 * ''Dermocystidium salmonis'' — a gill parasite of salmon * ''Dermocystidium sinensis'' * ''Dermocystidium sinipercae'' — a parasite of Chinese perch * ''Dermocystidium vejdovskyi'' Jírovec 1939 — a parasite of pike

References

* Mesomycetozoea Parasitic opisthokonts Eukaryote genera Parasites of fish Opisthokont genera {{Holozoa-stub