''Protocotyle euzetmaillardi'' is a species of

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 repro ...

n of the family Hexabothriidae. It is the third described species of the

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 nom ...

'' Protocotyle'', after '' Protocotyle grisea'' (Cerfontaine, 1899) Euzet & Maillard, 1974Euzet, L. & Maillard, C. 1974: Les Monogènes Hexabothriidae Price, 1942. Historique, systématique, phylogenèse. Bulletin du Muséum National d'Histoire Naturelle, 3° série, 206, Zoologie 136, 113-141
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and '' Protocotyle taschenbergi'' (Maillard & Oliver, 1966Maillard, C. & Oliver, G. 1966: Monogenea, Hexabothriidae. Vie et Milieu Série A: Biologie marine, 17, 1201-1216.) Euzet & Maillard, 1974. The body is 4.5-6.1 millimetres in length, elongate, and it includes, like all

ns, a posterior attachment organ called

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 ...

. The haptor is symmetrical, armed with six suckers, each provided with one hook-shaped

sclerite A sclerite (Greek , ', meaning " 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. Instead it refers most commonly ...

, and there is a lateral appendix bearing a single pair of terminal suckers and a single pair of hooks (also called hamuli). There is a single ovary, located at mid-length of the body, and numerous

testes 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 testoste ...

, more posterior. The oötype wall has longitudinal rows of large cells (a structure called "ootype côtelé" by Euzet & Maillard, 1974). The eggs are elongate, fusiform, with a single terminal filament. The species is distinguished from other species of the

'' Protocotyle'' by the following combination of characters: posterior lobe of seminal vesicle absent, diverticulum of oviduct present, and small body size. Hexanchus nakamurai JNC2615 body 1

It is ectoparasite on the gills of a deep-sea fish, the bigeyed sixgill shark ''

Hexanchus nakamurai The bigeyed sixgill shark (''Hexanchus nakamurai'') is a cow shark of the family Hexanchidae. Its dorsal surface has a brownish-gray color, and is sharply separated from the light coloring of its ventral surface. The eyes are a fluorescent gre ...

''. It has been found off New Caledonia, in the South Pacific Ocean on a single shark in 2008 and never found again since. It is the single species of

n known from this

shark Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachi ...

. Both other species of '' Protocotyle'' are parasitic on the gills of the bluntnose sixgill shark ''

Hexanchus griseus The bluntnose sixgill shark (''Hexanchus griseus''), often simply called the cow shark, is the largest hexanchoid shark, growing to in length. It is found in tropical and temperate waters worldwide and its diet is widely varied by region. The ...

'';Laubier, L., Maillard, C. & Oliver, G. 1966: Contribution à l'étude des parasites du "griset": ''Hexanchus griseus'' (Bonnaterre, 1788). Vie et Milieu, Série A: Biologie marine, 17, 1197-1199. thus, species of '' Protocotyle'' seem to be restricted to species of ''

Hexanchus The sixgill sharks are a genus, ''Hexanchus'', of deepwater sharks in the family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purp ...

''. The name of the species, ''euzetmaillardi'', means that it was named in honour of both Professor Louis Euzet, a famous French parasitologist, and Claude Maillard, a collaborator of Professor Louis Euzet, both authors of a major work about hexabothriids.

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External links

{{Taxonbar, from=Q2090271 Polyopisthocotylea New Caledonia Animals described in 2011