{{short description|Species of worms}} {{Speciesbox | image = Goto 1894 - Studies on the Ectoparasitic Trematodes of Japan - Plate 1 - Microcotyle caudata.png | image_caption = ''Microcotyle caudata'', drawing from original description | genus = Microcotyle | species = caudata | authority = Goto, 1894 | synonyms = *''Microcotyle (Microcotyle) caudata''<small> (Goto, 1894) Unnithan, 1971</small><ref name="Unnithan1971"/> }}
'''''Microcotyle caudata''''' is a species of monogenean, parasitic on the gills of a marine fish. It belongs to the family Microcotylidae.<ref name="Goto1894">{{cite journal|last1=Goto|first1=Seitaro.|title=Studies on the ectoparasitic Trematodes of Japan|year=1894|doi=10.5962/bhl.title.56506|doi-access=free|hdl=2027/coo.31924003409327|hdl-access=free}} {{open acess}}</ref>
==Systematics== ''Microcotyle caudata'' was first described by Goto in 1894, based on specimens obtained from the gills of rockfish, ''Sebastes'' sp.<ref name="Goto1894"/> Unnithan created the subgenus ''Microcotyle'' in which he placed ''Microcotyle caudata'' as ''Microcotyle (Microcotyle) caudata''.<ref name="Unnithan1971">Unnithan, R. V. (1971). On the functional morphology of a new fauna of Monogenoidea on fishes from Trivandrum and environs. Part IV. Microcotylidae sensu stricto and its repartition into subsidiary taxa. American Midland Naturalist, 366-398.</ref> ''Microcotyle caudata'' was redescribed by Yamaguti based on two specimens found on the gills of ''Sebastodes inermis'' (currently ''Sebastes inermis'' <ref name="Nitta & Nagasawa2015"/> )from Ise Bay, that differs from ''Microcotyle caudata'' of Goto only by the characters of the esophagus and the frame of clamps.<ref name="Yamaguti1934">Yamaguti, S. (1934). Studies on the helminth fauna of Japan. Part 2, Trematodes of fishes, I. Japanese Journal of Zoology, 5(3), 249-541.</ref> Four years later, Yamaguti provided some measurements of ''Microcotyle caudata'' based on several specimens recovered from the gills ''Sebastodes inermis''.<ref name=" Yamaguti1938"> Yamaguti, S. (1938). Studies on the helminth fauna of Japan. Part 24. Trematodes of fishes, V. Japanese Journal of Zoology, 8(1), 15-74.</ref> Yamaguti hesitated in assigning his specimens to ''Microcotyle caudata'' as he was uncertain of the extent of variability of the number of clamps according to individuals. He even pointed that the specimens of ''Microcotyle caudata'' recovered from ''Sebastodes inermis'' may represent a distinct species.<ref name="Yamaguti1934"/> An issue that remains currently is that ''Sebastes inermis'' (= ''Sebastodes inermis'') was separated into three species (''S. inermis'', ''S.ventricosus'', and ''S. cheni'') by Kai and Nakabo in 2008, and thus it is unclear which species corresponds to Yamaguti (1938)’s host <ref name="Nitta & Nagasawa2015">Nitta, M., & Nagasawa, K. (2015). A checklist of the monogeneans (Platyhelminthes) parasitic on fishes and invertebrates of the Seto Inland Sea, Japan (1894–2015), with new locality records for ''Anoplodiscus spari'' (Anoplodiscidae) and ''Dactylogyryus gotoi'' (Dactylogyridae). Bulletin of the Hiroshima University Museum, 7, 117-127. [https://home.hiroshima-u.ac.jp/museum/siryou-data/kennkyuuhoukoku7/09%20nitta.pdf PDF] {{open acess}} </ref>
==Morphology== ''Microcotyle caudata'' has the general morphology of all species of ''Microcotyle'', with an elongated symmetrical body. The body comprises an anterior part which contains most organs and a posterior part called the haptor. The haptor bears about 50 clamps, arranged as two rows (about 25 on each side). The clamps of the haptor attach the animal to the gill of the fish. There are also two buccal suckers provided with a membranous septum and situated at the anterior extremity. The digestive organs include an anterior, terminal mouth, a pharynx, and a posterior intestine with two branches provided with lateral branches both inwards and outwards; the left branch and extends beyond the vitellarium into the caudal haptor while the right branch ends with the vitellarium. Each adult contains male and female reproductive organs. The reproductive organs include a genital atrium opening on the same level as the beginning of the intestinal branches, armed with conical and slightly curved spines, unarmed vagina opening behind the common genital opening, at about six times as far forwards from the anterior end of the ovary, a single ovary, with the oviduct end on the right side, thence extending towards the left, presenting a convex border in front, 23 large testes posterior to the ovary and occupy a little less than one quarter of the whole length of the body.<ref name="Goto1894"/> The egg is fusiform, with a very long filament at only one pole and a shorter one at the other.<ref name=" Yamaguti1938"/> In the original description Goto noted that the curvatures of the body observed in some specimens were not taken into account. He also pointed out that the length of the body varies considerably according to the different state of contraction.<ref name="Goto1894"/>
==Hosts and localities== [[File:Sebastes Inermis.jpg|thumb|left|The Darkband Rockfish ''Sebastes inermis'' is reported as host of ''Microcotyle caudata'']] [[File:Sebastes norvegicus1.jpg|thumb|left|The golden redfish ''Sebastes norvegicus'' is also reported as host of ''Microcotyle caudata'']] [[File:Sebastes mentella.jpg|thumb|left|The Beaked redfish ''Sebastes mentella'', another Sebastidae reported as host of ''Microcotyle caudata'']] [[File:Helicolenus dactylopterus dactylopterus.jpg|thumb|left|The Blackbelly rosefish ''Helicolenus dactylopterus'', host of ''Microcotyle sebastis'']] [[File:Grosserdrachenkopf-02.jpg|thumb|left|One Scorpaenidae, the red scorpionfish ''Scorpaena scrofa'', is reported as host of ''Microcotyle sebastis'']] The type-host of ''Microcotyle caudata'' is ''Sebastes'' sp. It was also reported on other Sebastidae: the Darkband Rockfish''Sebastodes inermis'' (currently ''Sebastes inermis''),<ref name="Yamaguti1934"/><ref name=" Yamaguti1938"/> the golden redfish ''Sebastes marinus'' (currently ''Sebastes norvegicus''),<ref name="Bakai2012"> Bakai, Yu. I. (2012). Ecological and parasitological characteristics of the golden grouper ''Sebastes marinus'' (Scorpaeniformes). Journal of the Murmansk State Technical University, 15 (4). [In Russian].</ref> the Blackbelly rosefish ''Helicolenus dactylopterus'',<ref name="Parukin1989">A.M. Parukhin, 1989, Parasitic Worms of Benthic Fishes of the Southern Seas, Naukova Dumka, Kiev, 1989 [In Russian]</ref> the blackbelly Rosefish ''Helicolenus maculatus'' ( currently ''Helicolenus dactylopterus''),<ref name="Parukin1989"/> the red scorpionfish ''Scorpaena scrofa'',<ref name="Parukin1989"/> and on the Beaked redfish ''Sebastes mentella''.<ref name="Melnikov2003">Melnikov, S. P., Bakay, Y. I., Bakay, I. V., Novikov, G. G., Stroganov, A. N., & Gory, V. (2003). Ecological and biological characteristics of redfish "Sebastes mentella" in Va and XIVb Divisions of ICES. ICES North-Western Working Group. [https://fishvice.hafro.is/lib/exe/fetch.php/nwwg:wd200309.pdf PDF] {{open acess}}</ref> When investigating the ecological and biological characteristics of redfish ''Sebastes mentella'', Melnikov el al. noted the absence of ''Microcotyle caudata'' in redfish from the pelagial zone.<ref name="Melnikov2003"/>
''Microcotyle caudata'' was first described from fishes caught off Mitsugahama off Japan.<ref name="Goto1894"/> It was also reported off Japan,<ref name="Yamaguti1934"/><ref name=" Yamaguti1938"/> Russia,<ref name="Bakai2012"/> Southeast Atlantic,<ref name="Parukin1989"/> Southwest Indian Ocean, the Mediterranean,<ref name="Parukin1989"/> and off the southwestern slope of Iceland.<ref name="Melnikov2003"/>
==References== {{Reflist}}
{{Taxonbar|from=Q2263911}}
Category:Microcotyle Category:Parasites of fish Category:Animals described in 1894 Category:Fauna of Japan