Morphological and Molecular Evidence of an Intergeneric Host-Range in Clavisodalis sentifer (Crustacea: Copepoda: Taeniacanthidae) Associated with Diadematid Sea Urchins from the Western Pacific.

Sea urchins have a wide variety of symbionts on their body surfaces and inside their bodies. Copepods of the genus Clavisodalis (Taeniacanthidae) collected from the esophagus of sea urchins of the genera Diadema and Echinothrix in southern Japan were identified based on their morphological characteristics, and molecular analysis was conducted to determine whether genetic variation occurs in copepods from different localities and hosts. Morphological observations identified individuals from southern Japan as Clavisodalis sentifer Dojiri and Humes, 1982, making this the first record of this species in the northern hemisphere and the first record of its genus in Japan. Morphological and molecular analysis suggested that the copepod specimens collected from multiple hosts across two genera would be the same species. Considering the typically observed high level of host specificity among taeniacanthid copepods, the utilization of hosts from two genera by C. sentifer is noteworthy.

From commensalism to parasitism within a genus-level clade of barnacles.

Understanding how animals evolve to become parasites is key to unravelling how biodiversity is generated as a whole, as parasites could account for half of all species richness. Two significant impediments to this are that parasites fossilize poorly and that they retain few clear shared morphological features with non-parasitic relatives. Barnacles include some of the most astonishingly adapted parasites with the adult body reduced to just a network of tubes plus an external reproductive body, but how they originated from the sessile, filter-feeding form is still a mystery. Here, we present compelling molecular evidence that the exceedingly rare scale-worm parasite barnacle Rhizolepas is positioned within a clade comprising species currently assigned to Octolasmis, a genus exclusively commensal with at least six different phyla of animals. Our results imply that species in this genus-level clade represent an array of species at various transitional stages from free-living to parasitic in terms of plate reduction and host-parasite intimacy. Diverging only about 19.15 million years ago, the route to parasitism in Rhizolepas was associated with rapid modifications in anatomy, a pattern that was likely true for many other parasitic lineages.

Ceratosomicola oki n. sp., a New Species of Copepod (Cyclopoida: Splanchnotrophidae) Parasitic on the Chromodoridid Nudibranch Glossodoris misakinosibogae Baba, 1988 Off the Oki Islands, Japan, with Microanatomical Observation Using Micro-CT.

A new species of the family Splanchnotrophidae Norman and Scott, 1906 (Cyclopoida) is described based on both sexes collected from off the Oki Islands, the Sea of Japan. Specimens of both sexes of Ceratosomicola oki n. sp. were found in the body cavities of Glossodoris misakinosibogae Baba, 1988 (Nudibranchia: Chromodorididae). The copepod is characterized by the following female characters: the cephalosome with a pair of dorsolateral horn-like processes; the prosome with hemispherical posterolateral lobes on the middle region. Non-destructive, micro-computed tomography (micro-CT) imaging performed on a single specimen of the nudibranch revealed a heavy infection by a total 17 specimens of C. oki n. sp. Almost all individuals of the copepod were attached on the surface of the middle to posterior parts of the visceral sac, forming a dense cluster. The four females bearing developed lateral processes on the prosome faced the anterior end of the visceral sac and positioned the posterior tip of the body under the secondary gills of the host. The males fitted in the gaps between the females' bodies. Further, the distribution and shape of the reproductive organs of both sexes were partially clarified by micro-CT imaging.

Choreftria shiranui, a new genus and species of cyclopoid copepod (Crustacea: Copepoda) associated with the worm goby from southern Japan, with the proposal of a new family.

A new genus and species of cyclopoid copepod, Choreftria shiranui n. g., n. sp. (Crustacea: Copepoda) is described based on an adult female found from the worm goby, Taenioides snyderi Jordan & Hubbs (Actinopterygii: Perciformes: Gobiidae), from mud flats in the Yatsushiro Sea, southern Japan. The new genus is characterized by bearing the following characters in the female: body distinctly segmented cyclopiform with 4-segmented prosome and 6-segmented urosome; genital somite clearly separated from first abdominal somite; antennule 7-segmented; antenna 4-segmented with one fused serrated claw and long claw on second endopodal segment; mandible reduced with one serrated blade; maxillule rod-like with one element; maxilla 2-segmented with recurved terminal claw; maxilliped 2-segmented; legs 1 to 4 biramous with 3-segmented rami. Since the copepod is not attributable to any of the known cyclopoid families, a new family, Choreftriidae n. fam. is established to accommodate Choreftria n. g. LSID urn:lsid:zoobank.org:pub:C1FB9F60-9871-4D4B-A1BF-3202BA24189F.

Distribution and Genetic Divergence of Deep-Sea Hydrothermal Vent Copepods (Dirivultidae: Siphonostomatoida: Copepoda) in the Northwestern Pacific.

Copepods in the family Dirivultidae are one of the most successful meiofauna in deep-sea hydrothermal vent fields and are abundant near venting fluid. Although vents are spatially limited ocean habitats, they are distributed widely in the Atlantic, Pacific, and Indian Oceans. However, knowledge of dirivultid biogeography and phylogeography remains limited, especially in the northwestern Pacific. Here, we obtained partial mitochondrial COI gene sequences of three dirivultids from the northwestern Pacific-Stygiopontius senokuchiae and an unidentified Chasmatopontius species from vent fields in the Izu-Bonin Arc and Stygiopontius senckenbergi associated with the squat lobster Shinkaia crosnieri in the Okinawa Trough-and analyzed them in comparison with existing data. The among-species sequence diversity exceeded 80 out of 560 bp (14% or 0.166 in Kimura 2-parameter distance), whereas the within-species diversity was less than 10 bp (2% or 0.018 in Kimura 2-parameter distance), with no genetic saturation. Each species formed a monophyletic clade and the genetic region targeted is deemed reliable for identifying species and populations for these copepods. Among the three genera targeted, only Chasmatopontius formed a monophyletic cluster, while Aphotopontius and Stygiopontius did not. Species delimitation analyses suggested the existence of cryptic species in Chasmatopontius. Subdivision among local populations was observed in Aphotopontius, but not in Stygiopontius in the same distribution, implying potential differences in dispersal ability among different genera of dirivultids. Further sampling is required, to fill the spatial gaps to elucidate the biogeography and evolution of dirivultids in the global deep ocean.

Three species of copepods parasitic on the blue mackerel Scomber australasicus Cuvier (Actinopterygii: Perciformes: Scombridae) from southern Japan, with description of a new species Colobomatus itoui n. sp. (Cyclopoida: Philichthyidae).

The blue mackerel Scomber australasicus is one of the major commercial fishes consumed in southern Japan. Three species of parasitic copepods were collected from S. australasicus in the East China Sea off the west coast of Kyushu Island, southern Japan. These copepods are each characterized based on the females: Pumiliopes scombri (Bomolochidae) differs from its congeners by the presence of fine ventral spinules on legs 2 to 4; Colobomatus itoui n. sp. (Philichthyidae) is characterized by having the cephalosome with a pair of dorsal hemispherical cephalic protrusions but without an apical cephalic process and the anal somite with a pair of posterolateral protrusions with a smooth tip; and Caligus kanagurta (Caligidae) is distinguishable from its congeners accommodated in the Caligus diaphanus-group by bearing an atypical bulged leg 4 with long protruded pectens. The collection of C. kanagurta in Japanese waters represents its new country record. Parasitic copepods reported from S. australasicus and its related species S. japonicus from the western Pacific Ocean are tabulated.LSID urn:lsid:zoobank.org:pub:382569AD-5188-4443-AAA8-1C2DB4FE2689.

Lomanoticola nishiharai n. sp., a New Species of Copepod Parasitic on the Facelinid Nudibranch, Sakuraeolis enosimensis (Baba, 1930), from the Seto Inland Sea, Western Japan, Including Histological Observations of the Female Lateral Body Process.

Splanchnotrophidae Norman and Scott, 1906 is a family of parasitic copepods that infest nudibranchian and sacoglossan sea slugs. In this study, a new species of splanchnotrophid copepod, Lomanoticola nishiharai n. sp., is described based on specimens of both sexes collected from the facelinid nudibranch, Sakuraeolis enosimensis (Baba, 1930), in the Seto Inland Sea off Hiroshima, central Japan. It represents the third species of Lomanoticola Scott and Scott, 1895 and is characterized by the following female characters: the cephalosome distinctly protruded; the second and third lateral processes on the body originated from same bases; the caudal rami bears a seta V which almost same as long as the rami. Ultrastructural observations revealed that the cuticular surface of the lateral process on the female body is covered with numerous protuberances that may have protective functions against the cellular immune system of the host.

Two new species of Sagum Wilson, 1913 (Copepoda: Siphonostomatoida: Lernanthropidae) parasitic on reef fishes off the Ryukyu Islands.

Two new species of parasitic copepods, Sagum gurukun n. sp. and S. bitaro n. sp. (Siphonostomatoida: Lernanthropidae), are described based on specimens collected from the gill filaments of the double-lined fusilier Pterocaesio digramma (Bleeker) (Actinopterygii: Perciformes: Caesionidae) and the five-lined snapper Lutjanus quinquelineatus (Bloch) (Actinopterygii: Perciformes: Lutjanidae), respectively, caught off Iriomote-jima Island, the Ryukyu Islands, East China Sea, Japan. The findings bring the number of species of Sagum to 14. The two new species are similar in the morphology of the head and the legs 3 and 4 to the three congeners, S. folium Ho, Liu & Liu, 2011, S. paracaesionis Izawa, 2014 and S. vietnamiensis Kazachenko, Kovaleva, Nguyen & Ngo, 2017. Sagum gurukun n. sp. is differentiated from the three congeners by the proportions of the caudal rami, the absence of leg 5, and the shape of the legs 1 and 2. Sagum bitaro n. sp. differs from the three congeners and S. gurukun n. sp. by the presence of the conical leg 5 armed with an apical seta. A key to the species of the genus Sagum, based on the available information on female morphology in previous publications and the present study, is provided. To date, a total of 19 species of lernanthropid copepods considered valid are known in Japanese waters.

Histopathology of a mesoparasitic hatschekiid copepod in hospite: does Mihbaicola sakamakii (Copepoda: Siphonostomatoida: Hatschekiidae) fast within the host fish tissue?

Mihbaicola sakamakii is a mesoparasitic copepod that infests the branchiostegal membranes of groupers (Perciformes: Serranidae). In this study, we observed M. sakamakii within host tissue. Histologically, copepods were found enclosed inside a pouch composed of the thickened epidermis of the host, tightly encased on all sides by the host epidermal pouch wall. There were no host blood cells or other food resources in the pouch lumen. Since the host epidermis was intact and continuous, even in the vicinity of the oral region of the parasite, the copepod would not have access to the host blood in this state. However, the stomach (ampullary part of the mid gut) was filled with granular components, the majority of which were crystalloids that likely originated from fish erythrocyte hemoglobin. We supposed that the parasite drinks blood exuded from the lesion in the fish caused by copepod entry into the host tissue. Invasion of the parasite may elicit immune responses in the host, but there were no traces on the copepod of any cellular immune reactions, such as encapsulation. The array of minute protuberances on the copepod cuticle surface may be involved in avoidance of cell adhesion. After the lesion has healed, the copepod is enclosed in a tough epidermal pouch, in which it gradually digests the contents of its stomach and continues egg production.

First record of Phoronopsis (Phoronida) from Japan, with a description of Phoronopsiscalifornica Hilton, 1930 from Okinawa.

Background: Phylum Phoronida currently contains two genera, Phoronis Wright, 1856 and Phoronopsis Gilchrist, 1907, with approximately thirteen speices. Phoronida is distributed worldwide, ranging from northern Europe to southern New Zealand and also from intertidal to 400 m depths. From Japanese waters, four species of Phoronis have been reported, viz. Phoronisijimai Oka, 1897, Phoronisaustralis Haswell, 1883, Phoronispsammophila Cori, 1889 and Phoronisemigi Hirose et al., 2014. New information: We describe the morphology of Phoronopsiscalifornica Hilton, 1930, based on five specimens collected at a sandy-mud habitat in Nago Bay and Oura Bay, Okinawa, Japan. We examined the internal anatomy by serial paraffin sections. We also examined the genetic distance of Japanese specimens from the other phoronid sequences in GenBank. This is the first record of Phoronopsis from Japanese waters and the fifth species record of phoronids in addition to the previously recorded four species of Phoronis.

The genus Hatschekia (Copepoda: Hatschekiidae) from pufferfishes (Tetraodontiformes: Tetraodontidae) off the Ryukyu Islands, Japan, with descriptions of four new species and a redescription of H. pholas.

Four new species of the genus Hatschekia Poche, 1902 (Copepoda: Siphonostomatoida: Hatschekiidae) are described based on female specimens collected from pufferfishes (Tetraodontiformes: Tetraodontidae) caught in coastal waters off the Ryukyu Islands, Japan: H. longiabdominalis sp. n. on Arothron hispidus (Linnaeus), H. geniculata sp. n. on A. hispidus (type host) and A. stellatus (Bloch et Schneider), H. ellipsocorpa sp. n. on A. mappa (Lesson), and H. boonah sp. n. on A. nigropunctatus (Bloch et Schneider) (type host) and A. meleagris (Schneider). Hatschekia longiabdominalis sp. n. and H. boonah sp. n. differ from all other congeners by sharing an unusual, projected abdomen and a fusiform trunk with posterior lobes; these two species are differentiated from each other by the shape of the dorsal chitinous frame on the cephalothorax. Hatschekia geniculata sp. n. can be distinguished by the combination of the following morphological characters: a rhomboidal cephalothorax with a pair of lateral conical protrusions, a cylindrical trunk with posterior lobes and a bent abdomen with a dorsal protrusion. Hatschekia ellipsocorpa sp. n. resembles H. pholas (Wilson, 1906) but can be distinguished from the latter by the possession of one distal and one inner setae on the terminal endopodal segment of legs 1 and 2. Hatschekiapholas is also redescribed based on female specimens from the tetraodontid A. stellatus. At present, 44 nominal species of the genus have been reported from Japan, including four new species described in this paper; 38 of them have been described originally from Japan.

A new genus and species of hatschekiid copepod (Siphonostomatoida) from groupers (Actinopterygii: Serranidae) collected off the Ryukyu Archipelago, Japan.

A new genus and species of copepod, Mihbaicola sakamakii n. g., n. sp., belonging to the siphonostomatoid family Hatschekiidae, is described based on the females collected from inside the tissue of the branchiostegal membrane in three species of the groupers, Epinephelus fasciatus (Forsskål) (type-host), E. merra Bloch and Cephalopholis leopardus (Lacépède), collected off Okinawa-jima Island and Iriomote-jima Island, Ryukyu Archipelago, North Pacific Ocean. The new genus can be distinguished from other hatschekiid genera by a combination of the following characters in the female: the head is composed of the cephalosome and the pedigerous somite; the cephalothorax is expanded into a pair of posteroventral lobes carrying leg 1; legs 1 and 2 are biramous and composed of the protopod and both rami are 2-segmented; leg 3 is absent; and leg 4 is represented by a rounded lobe with a chitinous pointed apical process.

Parasitic copepods from two species of commercial fishes collected off Iraq, with description of Hatschekia shari n. sp.

Two species of parasitic copepods, including one new species, are described based on specimens collected from off Basrah, Iraq (Arabian Gulf). Hatschekia shari n. sp. (Siphonostomatoida: Hatschekiidae) was found from the gill filaments of the spangled emperor Lethrinus nebulosus (Forsskål) (Perciformes: Lethrinidae). The new species is characterised by the following characters in the female: a rectangular cephalothorax with dorsal frame composed of two short and one long bifid longitudinal bars, connecting to one short and one long latitudinal bars; elongate, cylindrical trunk without posterolateral processes or lobes; absence of parabasal papillae; and antennae bearing middle segments without narrow median part and with terminal claws without basal conical processes. Bactrochondria formosana Ho, Lin & Liu, 2011 (Cyclopoida: Chondracanthidae) was found on the gill filaments of the largescale tonguesole Cynoglossus arel (Bloch & Schneider) (Pleuronectiformes: Cynoglossidae). Close comparison of the specimens of B. formosana collected from off Iraq with the original description revealed some differences in elements and ornamentations on the body and appendages. Our finding of B. formosana represents not only a new record from the Indian Ocean but also from a new host.

Two new species of Cardiodectes Wilson, 1917 (Copepoda: Siphonostomatoida: Pennellidae) from gobiid fishes (Actinopterygii: Perciformes) in the western Pacific Ocean.

Two new species of the genus Cardiodectes Wilson, 1917 (Siphonostonatoida: Pennellidae) are described based on females from gobiid fishes (Actinopterygii: Perciformes) in coastal waters of the Pacific Ocean. Both new species belong to the 'rubosus' group sharing a trunk without an abdomen. Cardiodectes bellwoodi n. sp. parasitizes Istigobius nigroocellatus (Günther) in Australian waters and differs from members of the 'rubosus' group by having a trunk length less than twice its width, and a pair of large anterior lobes with branched processes. Cardiodectes shini n. sp. is similar to C. asper Uyeno & Nagasawa but is distinguishable by the presence of a well-developed, bilobed process between the bases of the maxillae, and by the cephalothorax bearing only two pairs of lobes.

A new subtidal species of the genus Petrolisthes Stimpson, 1858 (Crustacea: Decapoda: Porcellanidae) from Okinawa, with an account of species of the genus known from the Ryukyu Islands, southwestern Japan.

A new porcellanid crab, Petrolisthes uruma sp. nov., is described based on a single specimen collected from Okinawajima Island in the Ryukyus, southwestern Japan. The unique holotype was collected from a subtidal depth of 10 m, though vast majority of the genus occur in intertidal to shallow subtidal zone. The new species is morphologically closest to P. noluccensis (De Man, 1888), but is distinguished by the weaker striation on the carapace, the proportionally longer carpus of the cheliped, the number of the anterior marginal teeth of the carpus of the cheliped, and the meri of the second and third pereopods each with a much stronger spine at the lateroventral distal angle. A brief note on species of Petrolisthes presently known from the Ryukyu Islands is given.

Two new species of the genus Anilocra Leach, 1818 (Isopoda: Cymothoidae) parasitic on reef fishes from the western Pacific.

Anilocra harazakii sp. nov. and Anilocra boucheti sp. nov. are described from specimens collected from Pterocaesio marri (Caesionidae) in the northern Ryukyu Islands, Japan and Myripristis kuntee (Holocentridae) off Madang, Papua New Guinea, respectively. Anilocra harazakii sp. nov. is characterized by the combination of the following characters in the female: the elongate narrow body dorsally vaulted; the pleonite 1 concealed by the pereonite 7; the uropod extending that of the angled pleotelson, and its endopod longer than the exopod; and the dactyli of only pereopods 2 and 3 with one nodule on anterior margins. Anilocra boucheti sp. nov. is characterized by the following: body with convex lateral margins; almost part of the pleonite 1 not concealed by the pereonite 7; pleonite 5 with posterolateral acute angle strongly produced; coxa 3 clearly smaller than coxae 1 and 2; the uropod not extending past the posterior margin of the pleotelson with the tip of one of the rami not exceeding the other; and the dactyli of pereopods 1-4 without nodules. Furthermore, the coloration, i.e., the orange body with black margins, of A. boucheti sp. nov. is unique. Bayesian inference tree using partial mitochondrial cytochrome c oxidase subunit I (COI) genes supported the monophyletic clade composed of the members of the genus Anilocra including the two new species. Since the wounds caused by A. harazakii sp. nov. are often hemorrhagic, the isopod might have severe negative effects on the host. LSID urn:lsid:zoobank.org:pub:1C426C15-6FB7-49E4-AD49-02BE532D9ABB.

Species of Taeniacanthus Sumpf, 1871 (Crustacea: Copepoda: Taeniacanthidae) parasitic on boxfishes (Tetraodontiformes: Aracanidae and Ostraciidae) from the Indo-West Pacific region, with descriptions of two new species.

Two new copepod species of the genus Taeniacanthus Sumpf, 1871 (Cyclopoida: Taeniacanthidae) are described from boxfishes (Aracanidae and Ostraciidae) caught in the Indo-West Pacific region: T. larsonae n. sp. from Ostracion nasus Bloch in the Arafura Sea and off Australia and Tetrosomus concatenatus (Bloch) off Japan; and T. thackerae n. sp. from O. immaculatus Temminck & Schlegel off Palau, O. rhinorhynchos Bleeker off Australia, Lactoria cornuta (Linnaeus) and Ostracion sp. off Japan, and Kentrocapros aculeatus (Houttuyn) in the East China Sea. T. larsonae n. sp. differs from its congeners by having several rows of spinules on the large pectinate process of the antenna and by differences in the shape of the sclerotised plates on the rostral area and structure of the maxilliped. T. thackerae n. sp. can be distinguished from its congeners by differences in the shape of the sclerotised plates on the rostral area, the structure of the maxilliped and ornamentation pattern of legs 1-4. Supplemental information for the female of Taeniacanthus ostracionis (Richiardi, 1870) and T. moa (Lewis, 1967), as well as the first description of the male of T. moa, are also provided based on new material collected from ostraciid hosts caught in the Arafura Sea and off Australia, Indonesia and Japan. The four taeniacanthid species reported from boxfishes exhibit variable levels of host-specificity and have broad geographical ranges within the Indo-West Pacific region.

Three new species of Hatschekia Poche, 1902 (Copepoda: Siphonostomatoida: Hatschekiidae) parasitic on boxfishes (Pisces: Tetraodontiformes: Aracanidae and Ostraciidae) in Japanese waters.

Three new species of Hatschekia Poche, 1902 are described from the gill filaments of three species of boxfishes captured off southern Japan: H. pseudostracii n. sp. on Kentrocapros aculeatus (Houttuyn) (Aracanidae); H. bibullae n. sp. on Lactoria diaphana (Bloch & Schneider) (Ostraciidae); and H. kuroshioensis n. sp. on Tetrosomus concatenates (Bloch) (Ostraciidae). Of the 93 currently valid species in the genus, these new species differ from the 87 species which lack four stout processes on the posterior margin of the intercoxal sclerites of legs 1 and 2. Those processes are present on the remaining six species and the three new species. Of these nine species, H. pseudostracii n. sp. is distinguished by having a T-shaped chitinous frame on the cephalothorax, the leg 1 exopod twice as long as the endopod and a small parabasal papilla. H. bibullae n. sp. can be differentiated by a combination of morphological features as follows: a well-developed, thumb-shaped parabasal papilla, the leg 1 exopod twice as long as the endopod and a trunk lacking posterior lobes. H. kuroshioensis n. sp. can be recognised by bearing a T-shaped chitinous frame on the cephalothorax, the leg 1 exopod is three times as long as the endopod and the trunk lacks posterior lobes.

A new species of parasitic copepod of the genus Hatschekia Poche, 1902 (Siphonostomatoida: Hatschekiidae) from filefishes (Pisces: Tetraodontiformes: Monacanthidae) from off Okinawa, Japan.

Hatschekia khahajya n. sp. is described from the gill filaments of two monacanthid fishes, Cantherhines dumerilii (Hollard) and Amanses scopes (Cuvier), caught off Okinawa, Japan. The new species can be distinguished from its congeners by the possession of the following combination of characters: cephalothorax length/trunk length ratio greater than 0.40; cephalothorax with a pair of lateral bars on the chitinous ring and a posterior pair of surface ridges; trunk with a bifurcate chitinous frame extending over its anterior third and with well-developed posterior lobes that extend beyond the abdomen; and four processes plus two spinular rows on the distal margin of the intercoxal sclerite of legs 1 and 2.

Pseudohatschekiidae, a new family for Pseudohatschekia branchiostegi Yamaguti, 1939 (Crustacea: Copepoda: Siphonostomatoida) from Branchiostegus spp. (Teleostei: Perciformes: Malacanthidae) in Japanese waters, with descriptions of the early developmental stages of P. branchiostegi.

The siphonostomatoid copepod Pseudohatschekia branchiostegi Yamaguti, 1939 is redescribed in detail based on specimens of both sexes collected from the gill filaments of three species of Branchiostegus Rafinesque (Teleostei: Malacanthidae) captured in Japanese waters. Descriptions of two naupliar stages and the infective copepodid stage of P. branchiostegi are also provided for the first time, and P. mebaru Yamaguti, 1939 is recognised herein as a junior synonym of P. branchiostegi. The latter copepod species represents a new family, the Pseudohatschekiidae fam. nov., of the Siphonostomatoida characterised by the following apomorphies: (a) two free pedigerous somites present between the cephalothorax and the genital complex; (b) a chelate antenna bearing two digitate processes and a thin cuticular covering; (c) a unilobate maxillule, with the palp completely fused to the endite and represented by a surface seta; (d) a rounded process furnished with pectinate membranes on the apex of the maxillary basis; (e) 2-segmented rami on legs 1-3; and (f) the absence of leg 4. It is also now evident that P. branchiostegi is a relatively common and abundant parasite of Branchiostegus spp. in the Far East.