Protomicrocotylidae is a family of

monogenea Monogeneans, members of the class Monogenea, 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 ...

n parasites in the order Mazocraeidea. The type-genus of the family is '' Protomicrocotyle''. The genus was created in 1922 by Thomas Harvey Johnston and Oscar Werner Tiegs for a worm previously described under the name ''Acanthodiscus mirabile'' by MacCallum in 1918.MacCallum, G. A. 1918: Notes on the genus ''Telorchis'' and other trematodes. Zoopathologica, 1, 81-97. The worm was parasitic on a crevalle jack of the New York Aquarium. Johnston & Tiegs originally proposed to create the subfamily Protomicrocotylinae, which was later raised to family level. Members of this family are elongate, flat, and long of 1 to several millimetres. The reproductive system includes many testes, located in the anterior region of the body between the ceca, and a single posterior

ovary The ovary () is a gonad in the female reproductive system that produces ova; when released, an ovum travels through the fallopian tube/ oviduct into the uterus. There is an ovary on the left and the right side of the body. The ovaries are end ...

. The male copulatory organ usually has spines. The posterior attachment organ or haptor, which attaches the worm to the host, is asymmetrical and has three pairs of small hooks. As most other polyopisthocotyleans, members of the family Protomicrocotylidae have posterior

clamps Clamp may refer to: Tools and devices *Brick clamp, an early method of baking bricks *Clamp (tool), a device or tool used to hold objects in a fixed relative position (many types listed) **C-clamp **C-clamp (stagecraft) **Riser clamp, a device u ...

on their haptor. These clamps are of the gastrocotylid type, i.e. they include two accessory

sclerite A sclerite (Greek language, Greek , ', meaning "hardness, hard") is a hardened body part. In various branches of biology the term is applied to various structures, but not as a rule to vertebrate anatomical features such as bones and teeth. Instea ...

s in addition to the other sclerites, but in some genera the clamps are simplified as microcotylid type, i.e. they have only five sclerites, and are even absent in members of the genus '' Lethacotyle''. Justine ''et al.'' observed that protomicrocotylids had specialized structures associated with their attachment organ, such as lateral flaps and transverse striations, which were not known in other monogeneans. They hypothesized that the

in protomicrocotylids were sequentially lost during

evolution Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...

, coinciding with the development of other attachment structures. To test the hypothesis, they calculated the surfaces of

and body in 120 species of gastrocotylinean

ns. The ratio of clamp surface: body surface was the lowest in protomicrocotylids. They concluded that

in protomicrocotylids were vestigial organs, and that occurrence of gastrocotylid and simpler microcotylid clamps within the same family were steps in an evolutionary sequence, leading to the absence of these attributes in species of '' Lethacotyle''. Protomicrocotylids are all parasitic on

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 teleost fish, of only two families, the Carangidae (jacks) and Sphyraenidae (barracudas).
MacCallum (1918) found many worms on the gills of a crevalle jack and noted that he had "no doubt that at times the species may be a serious menace to the life of the fish".

Genera

;According to the World Register of Marine Species * '' Bilaterocotyle'' Chauhan, 1945Chauhan, B. S. 1945: Trematodes from Indian marine fishes. Part I. On some new monogenetic trematodes of the sub-orders Monopisthocotylea Odhner, 1912 and Polyopisthocotylea Odhner, 1912. Proceedings of the Indian Academy of Sciences, Section B, 21, 129-159. * '' Bilaterocotyloides'' Ramalingam, 1961 * '' Chauhanocotyle'' Khoche & Dad, 1975 * '' Lethacotyle'' Manter & Price, 1953Manter, H. W. & Prince, D. F. 1953: Some Monogenetic Trematodes of marine fishes from Fiji. Proceedings of the Helminthological Society of Washington, 20, 105-112. * '' Neomicrocotyle'' Ramalingam, 1960Ramalingam, K. 1960: Morphological descriptions of a new genus ''Neomicrocotyle'' and three new species of the genus ''Protomicrocotyle'' (Monogenea) with a discussion on their taxonomic position. Proceedings of the National Institute of Sciences of India. Part B, Biological Sciences, 26, 367-378. * '' Protomicrocotyle'' Johnston & Tiegs, 1922Johnston, T. A. & Tiegs, O. W. 1922: New gyrodactyloid trematodes from Australian fishes together with a reclassification of the super-family Gyrodactyloidea. Proceedings of the Linnean Society of New South Wales, 47, 83-131. * '' Vallisiopsis'' Subhapradha, 1951 * '' Youngiopsis'' Lebedev, 1972

References

{{Taxonbar, from=Q5018598 Platyhelminthes families