Search

The coastal waters of Vietnam are home to a wide diversity of fishes, but the parasite diversity of these potential hosts is much less well characterized. To begin addressing this knowledge gap, we carried out surveys of myxozoan parasites in fishes collected from Nha Trang Bay in Vietnam's East Sea in 2018-2019. Mugilid fishes were collected in March-April 2018, January-February 2019, and November-December 2019, and examined for myxozoans. Myxospores consistent with those of the genus Ellipsomyxa were found in the gall bladder of four mullet species, and we thoroughly characterized those from Planiliza melinoptera. Myxospores were elliptoid and devoid of striation, with a distinct sinuous suture line. Polar capsules were pyriform and oriented toward the poles of the spore. Morphological features were compared to nominal species and this species from Vietnam was distinct. Phylogenetic analysis based on partial small subunit rDNA sequence revealed that broadly, Ellipsomyxa species split into three phylogenetic lineages, and although in some branches there are groupings by host family, habitat or locality, there are no clear phylogenetic patterns. The new species we encountered in P. melinoptera had a close sister relationship with Ellipsomyxa adlardi, with both species part of a larger subclade within the Ellipsomyxa lineage. Despite this phylogenetic similarity, these species were morphologically distinct, and partial large subunit DNA sequences were only 93% similar to each other. A combination of the morphological characteristics and molecular data suggest that this is an undescribed species and we propose the name Ellipsomyxa gordeyi n. sp., Competing Interests: Declaration of competing interest The authors declare they have no conflict of interest or competing interests. ORCID. Yurakhno, VM: 0000–0002–0571-6716. Ha,VT:0000–0001-7740-954×. Whipps, CM: 0000–0001–6139-0426., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Myxosporean parasites Kudoa spp. have been reported in several marine fish species worldwide. However, little is known about the contamination of these parasites in raw fish in Southeast Asia, where the consumption demand of uncooked fish is increasing. In 2019, the occurrence of several cases of raw yellowfin tuna (Thunnus albacares) obtained from retail shops with the presence of unknown white, nodular cysts within the musculature have raised public health concerns for the consumption of raw marine fish in Vietnam. Microscopic examination revealed numerous myxospores with the quadratic shape of the Kudoidae. Morphologically, stained spores detected in this study are suspected to Kudoa thunni. To confirm the suspected Kudoa species, further examination of the 18S small-subunit (SSU) was conducted and the results of nucleotide sequence analysis obtained from nodular cysts revealed 99.18-100% identity to that of Kudoa thunni sequences available in GenBank. Detection of K. thunni infection in tuna in Southeast Asia highlights the need for appropriate surveillance and control measures to ensure high quality standards and safety on raw fish production and consumption., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The present study describes Hoferellus jutubensis n. sp., a myxozoan parasite found in the urinary bladder of the driftwood catfish Ageneiosus inermis, captured on Jutuba Island in the state of Pará, northern Brazil. A total of 30 A. inermis specimens were examined, of which 26 (86.7%) had myxospores and polysporic plasmodia of varying shapes and sizes dispersed in the lumen of the urinary bladder, either floating freely or attached to the epithelium. In the apical view, the myxospores of Hoferellus jutubensis n. sp. are rounded, 6.1 ± 0.2 (5.7-6.3) μm long and 5.5 ± 0.3 (5.2-6.0) μm wide, with two sub-spherical polar capsules, equal in size and shape, 2.5 ± 0.2 (2.3-2.7) μm long and 1.7 ± 0.2 (1.4-2.2) μm wide. The phylogenetic analysis of a partial sequence of the SSU rDNA gene, indicated that the new species is the sister taxon of Hoferellus azevedoi, with these two species forming a Brazilian lineage of Hoferellus. The comparison of the morphological and molecular data with those of the existing members of the genus confirmed the species status of Hoferellus jutubensis n. sp., which adds one further Hoferellus taxon to the known myxosporean diversity of the Amazon basin., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Kudoa ocellatus n. sp. was found in the musculature of Astronotus ocelattus (Agassiz, 1831) from the Arari River on Marajó Island in Pará, Brazil. The new species forms pseudocysts in the epaxial and hypaxial musculature composed of various spores that are pseudoquadrate in the apical view. In the lateral view, the spores were triangular or pyramidal. In the lateral view, the spores were 46 ± 0.11 μm (4.5-4.8) in length and 6.6 ± 0.3 μm (6.2-7.2) in width, with four pyriform polar capsules of equal size that measured 2.0 ± 0.16 μm (1.8-2.2) in length and 1.5 ± 0.18 μm (1.3-1.8) in width. Based on the partial (1418 bps) sequence of the SSU rDNA gene, Kudoa ocellatus n. sp. was distinct from all the other Kudoa species deposited in GenBank. The phylogenetic Bayesian Inference and P distance placed the new species together with the other Kudoa species that parasitize freshwater Amazonian fish. The morphological evidence, together with the SSU rDNA gene sequence, supported the description of Kudoa ocellatus n. sp., a distinct new species of the genus, which parasitizes a freshwater Amazonian cichlid., (Copyright © 2021 Elsevier B.V. All rights reserved.)

We described two novel myxozoan parasite species Ceratomyxa argentina n. sp. and Ceratomyxa raneyae n. sp. from the gall bladder of Raneya brasiliensis (Kaup) from the Patagonian coast of Argentina. Both species can be distinguished from other ceratomyxids by myxospore and polar capsule (nematocyst) morphology and morphometry, fish host and geographic locality. Phylogenetic reconstruction using ssrDNA gene sequences showed that the two new species are placed in a long-branching ceratomyxid clade which also include Ceratomyxa appendiculata Thélohan, 1892, Ceratomyxa anko Freeman, Yokoyama and Ogawa, 2008, Ceratomyxa pantherini Gunter, Burger and Adlard, 2010 and Pseudoalataspora kovalevae Kalavati, MacKenzie, Collins, Hemmingsen and Brickle, 2013. This study documents additional biodiversity of marine myxozoans in the South Atlantic, a region still largely unexplored for this group of parasitic cnidarians., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The present study describes a new coelozoic, eukaryotic microparasite of the genus Ellipsomyxa Køie, 2003 (Ceratomyxidae: Myxozoa) found parasitizing the gallbladder of Satanoperca jurupari Heckel, 1840 collected in the Curiaú River Environmental Protection Area in Macapá, Amapá state, Brazil. The fish were collected using mesh cast net. The gallbladders were examined, preserved in 80% alcohol for molecular analysis (SSU rDNA gene), and fixed in Davidson for histological slide preparation. The new parasite had a prevalence of 81% in the gallbladder, asymmetric plasmodia, irregular free spores in the bladder fluid, with no cyst formation. The spores are elliptical, with characteristics of the genus Ellipsomyxa, and they had a mean length of 10.11 (8.56-10.5) μm, mean width of 7.81 (5.96-9.56) μm, and thick walls. The polar capsules are sub-spherical in shape, slightly asymmetrical, with a mean length of 3.12 (2.31-3.99) μm and mean width of 2.5 (2.22-2.95) μm, containing polar filament with five or six coils perpendicular to the longitudinal axis of the capsule. The Bayesian Inference assigned the new species to a subclade formed by a lineage of Ellipsomyxa species from the Amazon region. Ellipsomyxa tucujuensis n. sp. is the sixth species of this genus described in fish from the Amazon region, and the first for the state of Amapá., (Copyright © 2021. Published by Elsevier B.V.)

Myxozoans are microscopic cnidarians that mainly parasitize fishes. The present study aimed to describe a new myxozoan parasite from the gills of Boulengerella cuvieri (Spix and Agassiz, 1829) by morphological and molecular analysis. The fish was collected in 2019 at the Pindaíba River, municipality of Cocalinho, Mato Grosso State, Brazil. Whitish and circular plasmodia were found in the primary gill filaments, occupying an intralamellar position, with an average of 0.5 mm in diameter. Henneguya Thélohan, 1892 myxospores found inside the plasmodia were elongated and ellipsoidal, consisting of two long and elliptical shell valves with two long, tapering caudal appendages. Morphometric measurements revealed a total spore length of 36.1 ± 2.0 μm; spore body length of 12.8 ± 0.5 μm; spore width of 4.9 ± 0.3 μm; tail length of 23.3 ± 1.6 μm; capsule length of 7.2 ± 0.4 μm; capsule width of 1.5 ± 0.2 μm; and 10 coils in the polar filament. Phylogenetic analysis showed that the isolates from this study were grouped into the main-clade of freshwater fishes, within a group of species parasitizing fishes from Brazil. Intergenotypic difference ranged from 23%-25.9% compared with other Brazilian myxozoan isolates. Using molecular and morphological characterization, this parasite was identified as a new species of the genus Henneguya., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Turkey has more than 200 endemic freshwater fish species, one of which is the Ankara nase, Chondrostoma angorense Elvira, 1987 (Cypriniformes: Leuciscidae), a food fish in northern Turkey. Like most endemic fish species in Turkey, its myxosporean parasite fauna (Cnidaria: Myxosporea) are not yet described. We surveyed twenty C. angorense from Lâdik Lake in northern Turkey, and identified two myxosporean parasites from gills of these fish: Myxobolus arrabonensis Cech, Borzák, Molnár, Székely, 2015, and a co-infection of a novel species, Myxobolus polati sp. nov. We characterized both infections based on myxospore morphology, morphometry, tissue tropism, small subunit ribosomal DNA sequence and phylogenetic analysis. Plasmodia of both species were observed in gills, but had distinct tropism: M. arrabonensis is an intrafilamental vascular type, and M. polati sp. nov. is an intralamellar vascular type. We identified M. arrabonensis on the basis of myxospore characters and 100% similarity to the type DNA sequence from the closely-related host C. nasus. The small subunit ribosomal DNA sequence of M. polati sp. nov. (1946 base pairs; GenBank Accession number MH392318) had a maximum similarity of 98% with any Myxobolus sp. from other Eurasian cypriniforms. Phylogenetic analysis revealed that M. polati sp. nov. is most closely related to gill-infecting Myxobolus diversicapsularis from Rutilus rutilus (L.). The present study is the first record of myxosporean species infecting C. angorense comprising a novel species, M. polati sp. nov. and a known species M. arrabonensis., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Coelozoic parasites of the family Myxidiidae were observed in fish of the order Characiformes captured in the middle Tocantins River, Maranhão, Brazil, within the transition between the Cerrado savanna biome and the eastern extreme of the Brazilian Amazon Forest. The analysis of the morphological characteristics of the parasites, complemented with a Bayesian phylogenetic analysis, supported the description of new specie Myxidium imperatrizensis n. sp., found parasitising the gallbladder of specimens of the fish Triportheus angulatus. The study is also only the second report of the occurrence of Myxidium parasites in fish of the family Triportheidae in Brazilian rivers. The results of the present study expand the known distribution of the genera Myxidium the basin of the Tocantins River, the largest hydrographic basin located entirely within Brazil, which encompasses parts of both the Cerrado and Amazon biomes., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Kudoa hexapunctata was taxonomically separated from Kudoa neothunni, but their main host is tuna. K. hexapunctata has been identified as causative agent of foodborne diseases associated with the ingestion of raw Pacific bluefin tuna (PBT) in Japan, but K. neothunni has not. Therefore, it is clinically and epidemiologically important to detect and distinguish these two species. In the present study, we developed a novel duplex polymerase chain reaction (dPCR) targeting the 28S rRNA gene sequences of K. hexapunctata and K. neothunni. The dPCR amplified the desired genetic regions of each species, and the detection limit was 10 copies/reaction. A total of 36 retail tuna samples from different fishing ports were purchased and tested by dPCR. Thirty-one tested positive for K. hexapunctata and four tested positive for K. neothunni. Several retail PBT samples were examined in some of the fishing ports, and among these samples, the detection rates of K. hexapunctata was higher than 85%, and the rates were similar between wild and farmed PBT. The detection rates of K. hexapunctata in wild and farmed retail PBT were 75% and 71%, respectively, in May. However, the rates in June and July were 100% for both. K. hexapunctata and K. neothunni myxospores were not observed in the dPCR-positive samples, except in juvenile PBT, suggesting that the number of parasites was insufficient to cause foodborne disease. Thus, dPCR is a useful method for detecting and distinguishing K. hexapunctata and K. neothunni, and can be used in epidemiological studies of these parasites., Competing Interests: Declaration of Competing Interest The authors declare that they have no conflict of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Plasmodia containing spores of a new species of myxozoan, Henneguya jundiai n. sp., were found in the gill arches of Rhamdia quelen catfish. The present study describes H. jundiai n. sp. based on morphological and molecular analysis. The mature spores were elongated and measured 26.9 ± 1.9 (22.9-29.2) μm in total spore length, 9.5 ± 0.4 (8.8-10.0) μm in spore body length, 4.6 ± 0.4 (4.1-5.5) μm in spore body width, 17.3 ± 1.8 (14.1-19.8) μm in tail length, 4.9 ± 0.3 (4.6-5.5) μm in polar capsule length and 1.4 ± 0.2 (1.2-1.7) μm in polar capsule width. The polar filaments had 6-7 coils. Histological analysis revealed the formation of a large plasmodium connected to the gill arch through the epithelial tissue. Ultrastructural analysis revealed the presence of a binucleated sporoplasm, as well as the polar capsules and the coils of the polar filament. Phylogenetic analysis found that H. jundiai n. sp. is located within a subclade formed by species of Henneguya which parasitize siluriform fish from Brazil. Henneguya jundiai n. sp. appears as a sister species of H. quelen. The results of the analyzes clearly indicated the existence of a new species, H. jundiai., (Copyright © 2019 Elsevier B.V. All rights reserved.)

This study presents morphologic, molecular and phylogenetic data about two new species of the genus Myxobolus and of the previously described Myxobolus colossomatis, all which are found infecting the Colossoma macropomum, a fish whose natural habitat is the Amazon Basin of Brazil, from where the specimens for this study were caught. A total of 51 C. macropomum specimens were examined between October of 2014 and January of 2016. Plasmodia of the myxosporeans were found infecting several organs: Myxobolus matosi n. sp. and Myxobolus longissimus n. sp. were respectively found in the inner face of the operculum and in the wall external surface of the stomach and gill arch. M. matosi n. sp. were 9.6 ± 0.4 μm in length, 7.0 ± 0.3 μm in width and 5.0 ± 0.3 μm in thickness of the myxospore. M. longissimus n. sp. measured 19.1 ± 0.4 μm in length, 9.4 ± 0.3 μm in width and 8.3 ± 0.4 μm in thickness. The polar capsules, which were elongated, showed 4.3 ± 0.4 μm in length and 1.9 ± 0.1 μm in width for M. matosi n. sp. and 10.5 ± 0.2 μm in length and 2.5 ± 0.1 μm in width for M. longissimus n. sp. The Myxobolus colossomatis had two myxospore morphotypes: 1) Ellipsoidal myxospores measuring 11.6 ± 0.4 μm in length and 7.6 ± 0.2 μm in width. Their elongated polar capsules measured 5.6 ± 0.2 μm in length and 2.5 ± 0.2 μm in width; 2) Oval myxospores measuring 10.4 ± 0.5 μm in length and 7.7 ± 0.3 μm in width. Their polar capsules were 5.4 ± 0.2 μm in length and 2.4 ± 0.0 μm in width. The number of turns of the polar filament was 7-8 coils. The molecular comparison of the small subunit ribosomal DNA (ssrDNA) showed a genetic divergence of 10.3% between M. matosi n. sp. and M. colossomatis, 22.4% between M. matosi n. sp. and M. longissimus n. sp., and 23.2% between M. longissimus n. sp. and M. colossomatis. Myxobolus cf. colossomatis, a parasite of Piaractus mesopotamicus, showed 11.1% of genetic divergence to M. colossomatis, demonstrating them to be distinct species. Phylogenetic analysis, based on sequences of the ssrDNA, showed the M. matosi n. sp. to be a sister species of M. colossomatis, and it also showed M. longissimus n. sp. to be a sister branch in the lineage composed by Myxobolus cf. cuneus and Henneguya pellucida., (Copyright © 2018 Elsevier B.V. All rights reserved.)

We describe two novel myxosporean parasites from Brachyplatystoma rousseauxii, an economically important freshwater catfish from the Amazon basin, Brazil. Myxobolus tapajosi n. sp., was found in the gill filaments of 23.5% of 17 fish, with myxospores round to oval in frontal view and biconvex in lateral view: length 15 (13.5-17) μm and width 10.7 (9.6-11.4) μm; polar capsules equal, length 5.8 (4.6-7.1) μm and width 3 (2.3-3.8) μm containing polar tubules with 6-7 turns. Ellipsomyxa amazonensis n. sp. myxospores were found floating freely or inside plasmodia in the gall bladder of 23.5% of fish. The myxospores were ellipsoidal with rounded extremities: length 12.8 (12.3-13.6) μm and width 7.6 (6.7-8.7) μm; with two equal, slightly pyriform polar capsules, length 3.8 (3.8-4.0) μm and width 3.1 (2.5-3.4) μm, containing polar tubules with 2-3 turns. We combined spore morphometry, small-subunit ribosomal DNA data, specific host, and phylogenetic analyses, to identify both of these parasites as new myxozoan species. Maximum likelihood and Bayesian analyses showed that Myxobolus tapajosi n. sp. clustered in a basal branch in a subclade of parasites from exclusively South American pimelodid fishes. Ellipsomyxa amazonensis n. sp. clustered within the marine Ellipsomyxa lineage, but we suspect that although the parasite was collected in freshwater, its hosts perform a large migration throughout the Amazon basin and may have become infected from a brackish/marine polychaete host during the estuary phase of its life., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Thelohanellus macrovacuolaris n. sp. is described during a survey on myxozoan diversity of common carp Cyprinus carpio L. in China. It is characterized by the presence of round or ellipsoidal plasmodium in the palate in the mouth of host. Mature spores were pyriform in frontal view, lemon shaped in lateral view, measuring 21.6±0.9 (19.3-23.8) long, 12.5±0.7 (10.3-13.6) wide, and 10.2±0.4 (9.8-11.8) thick. Most spores were surrounded by the membrane sheath. Single polar capsule was round with an apophysis at its top end presented close to apex of spore, measuring 9.1±0.6 (8.0-10.0) in length, 8.6±0.5 (7.8-9.6) in width. Polar filaments coiled, with 7 to 8 turns. A large, round iodinophilous vacuole was present, with 5.8-7.5 in diameter. The present species is morphologically distinct from all other Thelohanellus species. The BLAST search indicated that the newly obtained small subunit ribosomal RNA (ssrRNA) gene sequence of T. macrovacuolaris n. sp. did not match any available sequences in GenBank. Phylogenetically, T. macrovacuolaris n. sp. was placed sister to Thelohanellus wangi in the Thelohanellus clade. Both morphology and ssrRNA gene sequence data revealed that the present parasite is a new species of genus Thelohanellus., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

A new myxosporean parasite is described from the gall bladder of the gilthead seabream Sparus aurata in a Southern Portuguese fish farm, with basis on light and transmission electron microscopy, as well as in molecular procedures. In the bile, young and mature mono- to disporic plasmodia were elliptical and presented smooth surface membranes. Crescent-shaped myxospores measured 6.7±0.7 (5.3-7.6) μm in length and 27.0±3.0 (19.7-31.2) μm in thickness. The myxospore wall was constituted by two symmetrical valves united along a slightly curved suture line, each presenting a lateral projection with a rounded end. Two equal-sized subspherical polar capsules, measuring 3.6±0.2 (2.9-3.8) μm in length and 3.5±0.3 (2.9-3.8) μm in width, were located at the same level, each displaying a polar filament coiled in 5 turns. Molecular analysis of the SSU rRNA gene confirmed the parasite as a new member of the genus Ceratomyxa, making this the fourth report of Ceratomyxa from the gall bladder of S. aurata in the Iberian Peninsula. This reinforces the assumption that species richness of ceratomyxids in South European sparids is high, but the phylogenetic analysis performed disagrees with the existence of a common ancestor for Ceratomyxa species infecting sparid hosts, as well as their clustering according to geographical location. The main Ceratomyxa clade is not monophyletic due to the inclusion of Palliatus indecorus and Pseudoalatospora kovalevae; a situation that will probably be resolved by the taxonomic revision of these genera., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

Since Kudoa septempunctata in olive flounder (Paralichthys olivaceus) was indicated to cause food poisoning in humans, other Kudoa species are suspected to have pathogenic potential. Recently, a myxosporean possibly associated with food poisoning in humans consuming raw Pacific bluefin tuna, Thunnus orientalis, was identified as Kudoa neothunni. This is a known causative myxosporean of post-harvest myoliquefaction in yellowfin tuna Thunnus albacares. Regardless of the significant differences in the 28S rDNA sequence and the pathological character (with/without myoliquefaction) between the two T. orientalis and T. albacares isolates, they were considered intraspecific variants of K. neothunni. However, the light and low-vacuum electron microscopic observations in the present study revealed that there were two morphotypes; pointed- and round-type spores, which were significantly differentiated by the ratio of suture width to spore width. Furthermore, the two morphotypes were genetically distinguishable by the 28S rDNA sequence analysis. This morphological and molecular evidence validates that the two Kudoa types are separate species, and thus the pointed- and round-types are referred to as K. neothunni and Kudoa hexapunctata n. sp., respectively. K. neothunni was detected solely from T. albacares, whereas K. hexapunctata n. sp. was found not only from T. orientalis but also from T. albacares., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

Thelohanellus wuhanensis Xiao & Chen, 1993 infects allogynogenetic gibel carp Carassius auratus gibelio (Bloch) forming numerous plasmodia in the skin, resulting in high mortality of juvenile host fish. Within this paper we supplement the identification of this pathogenic species with information on its ultrastructural and histological characteristics. Measurements of the spores corresponded to the original description, but asymmetry in the spore shape was recorded. Scanning electron microscopy revealed that the spore surface was smooth and the sutural ridge of the anterior end was asymmetric as one side was thinner. In addition, the sutural line was either straight or "S" like. Transmission electron microscopy showed that most spores were surrounded by a membranous sheath, while some sheaths were difficult to observe under light microscopy as the closeness of the sheath to the valves. The small electron-dense granules in the sporoplasm ranged from 0.66 to 1.14 μm in diameter, but their function was unknown. Histology showed that the plasmodia of T. wuhanensis developed in the stratum spongiosum of skin dermis. The presence of melanocytes around the plasmodia was responsible for the black spots on T. wuhanensis cyst. The plasmodia were curved, perhaps to expand the surface area in contact with adjacent host tissue, facilitating the attainment of nutrients from the host., (Crown Copyright © 2014. Published by Elsevier Ireland Ltd. All rights reserved.)

Unicapsula seriolae (Myxozoa; Multivalvulida) was found in the trunk muscle of Malabar grouper Epinephelus malabaricus caught off Wakayama Prefecture, Japan. Numerous filamentous or sesamoid brown to black lesions were observed in the skeletal muscle. Histopathological observation indicated that the lesions were myxosporean plasmodia encapsulated by a fibrous layer, accompanied by melanin deposition. Spores having one large and two rudimentary polar capsules were subspherical in shape and 6.6 × 6.9 μm in size. Scanning electron microscopy revealed that spores were composed of three spore valves. Morphological characteristics were consistent with U. seriolae, which is reported to cause myoliquefaction in yellowtail kingfish Seriola lalandi in Australia. Molecular analysis of the SSU and LSU rDNA supported identification of the species as U. seriolae. This is the first report of Unicapsula in Japan., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

Enteromyxum leei (Myxozoa) has been identified as the aetiological agent of morbidity and mortality in captive feral parrotfish, Sparisoma cretense held at the facilities of Cretaquarium, the public aquarium of the Hellenic Centre for Marine Research in Crete. The parasite caused substantial mortality to the parrotfish exceeding 60% over a period of 3.5 months. Here we describe the course of disease, the effects of the parasite on the host based on histopathological observations and we provide morphological and molecular data on the parasite., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Kudoa leptacanthae n. sp. was identified within the pericardial cavities of two apogonid species, Zoramia leptacantha and Zoramia viridiventer, from waters off Lizard Island on the Great Barrier Reef. The species shows a close taxonomic affinity, both morphologically and genetically, to Kudoa shiomitsui Egusa & Shiomitsu 1983 reported from a tetraodontid and scombrid, both from Japan. The infection was at high prevalences (average = 75.8% ± 0.63, n = 343) within schools of the two host species. Different sporogonic stages ('developing' and 'fully-developed') were observed in pseudocysts within the pericardium of the hosts. Kudoa leptacanthae n. sp. appears to be a persistent infection within the Zoramia species hosts. No seasonal variation was detected for this host/parasite system and the parasite did not affect host condition, when assessed using host length/weight ratio as a coarse indicator. We hypothesise that a source of infection in close proximity to the home patch reef of apogonid schools may lead to the high prevalence and intensity of infection reported in this study., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Henneguya cartilaginis n. sp. (Myxozoa: Myxosporea) is described from wild masu salmon Oncorhynchus masou masou in Hokkaido, Japan. H. cartilaginis n. sp. produced white cysts, up to 3mm in size, in the head of masu salmon. Infected fish exhibited cranial protrusion due to the cysts. Spores (11.4 × 8.6 μm) of H. cartilaginis n. sp. were egg-shaped with the posterior end more pointed and possessed two caudal appendages (34.2 μm average length). Histological observations revealed that large plasmodia possessing fine fibrous pseudopodia on the surface developed in the head cartilage. H. cartilaginis n. sp. resembles H. cerebralis, which was described from the cranial cartilage of Kosogol grayling Thymallus nigrescens in Mongolia. However, they were distinguishable by spore morphology. Molecular analysis of the 18S rDNA sequences indicated that H. cartilaginis n. sp. was most closely related to Henneguya zschokkei, H. nuesslini and H. salminicola of salmonid fish, with genetic similarities of 95.3%, 95.1% and 93.9%, respectively. Based on these differences in spore morphology, molecular data, the site of infection and geographical distribution, the present species is considered to be a new species., (Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.)

In 1991, the first record of Sphaerospora epinepheli was described as a kidney parasite of wild and cultured malabar grouper, Epinephelus malabaricus, along coastlines of Thailand, the Gulf of Thailand and the Andaman Sea. However, the present study detected high infection of this parasite in kidney renal tubes of orange spotted grouper, Epinephelus coioides, collected from Andaman Sea. The highest infection rate of 36.82% was observed during the rainy season in 2009 in Phang-Nga Bay, in the north of Andaman Sea, which is an important grouper production site in Thailand. The biological and histopathological data of the parasite in this new host record are presented. Species classification is described based on morphological data of mature spore and molecular analysis of myxosporean 18S rDNA phylogeny including that of S. epinepheli which infected E. malabaricus. The genetic position of this parasite found in two host species was also studied. The phylogenetic tree analysis of small-subunit rDNA sequences of S. epinepheli from both infected hosts was constructed using two algorithms, maximum likelihood (ML) and Bayesian inference (BI). They were placed in the clustered basal sphaerosporid clade that contain four long SSU rDNA sphaerosporid species including Sphaerospora truttae, Sphaerospora elegans, Sphaerospora ranae, Sphaerospora fugu and Bipteria formosa with strong bootstrap supports. Histopathologically, renal intratubular myxosporean spores were associated with tubulonephosis, tubular necrosis, chronic interstitial nephritis and mimic membranoproliferative glomerulonephritis. This myxosporean parasite appears to be a significant pathogen on the basis of pathological changes in the renal tubules and is highly distributed in orange-spotted grouper., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Six novel species of Chloromyxum Mingazzini, 1890 are described using a whole evidence approach combining morphometric and molecular data, together with features of their biology. Elasmobranchs were collected in Australian waters, from the Great Barrier Reef, Queensland, off Lizard and Heron Islands; from Moreton Bay, southeast Queensland; off Hobart, Tasmania; and from the Tamar River, Launceston, Tasmania. The novel species proposed here are: Chloromyxum hemiscyllii n.sp. from Hemiscyllium ocellatum; Chloromyxum kuhlii n.sp. from Neotrygon kuhlii; Chloromyxum lesteri n.sp. from Cephaloscyllium laticeps; Chloromyxum mingazzinii n.sp. from Pristiophorus nudipinnis; Chloromyxum myliobati n.sp. from Myliobatis australis; and Chloromyxum squali n.sp. from Squalus acanthias. A seventh species from Squalus acanthias is also reported but due to limited material is not formally described. Molecular phylogenetic analyses revealed that the genus Chloromyxum is polyphyletic, and species from elasmobranchs form a well-supported sister clade, with the type species Chloromyxum leydigi, to all other congeneric species clustering within the freshwater myxosporean clade. Morphological analysis showed that elasmobranch-infecting species are predominantly pyriform shaped, have clearly thickened spore apex and possess caudal filaments, compared to other Chloromyxum species which are generally spherical or subspherical, and lack caudal filaments. These morphological and phylogenetic data provide further support for the erection of new genera, but we conservatively consider the species described in this study and other elasmobranch-infecting Chloromyxum species as Chloromyxum sensu strictu, whilst the freshwater teleost infecting and amphibian infecting species we will assign as Chloromyxum sensu lato, until more comprehensive data are available., (Crown Copyright © 2011. Published by Elsevier Ireland Ltd. All rights reserved.)

A survey of the myxosporean fauna of Australian marine fishes revealed the presence of a number of putative species of Kudoidae (Multivalvulida) forming pseudocysts between the outer meningeal layer and the outer surface of the brains of the lutjanids Caesio cuning, Lutjanus carponotatus, Lutjanus ehrenbergii and Lutjanus fulviflamma and the mugilid Liza vaigiensis from Lizard Island on the Great Barrier Reef, Australia and Lutjanus lemniscatus off Ningaloo Reef, Western Australia. Morphometric data combined with Bayesian inference and maximum likelihood analyses of small subunit (SSU) and large subunit (LSU) ribosomal DNA (rDNA) was used for species identification and to explore relationships among these taxa. The brain-infecting taxa examined here formed a well-supported clade to the exclusion of non-brain infecting species in the phylogenetic analyses. The combined diagnostic approach identified an undescribed taxon, Kudoa lemniscati n. sp., from the brain of L. lemniscatus (Perciformes: Lutjanidae) off Ningaloo Reef, Western Australia, which we describe and characterise here. K. lemniscati n. sp. can be distinguished from all other species of Kudoa based on the combination of the distinct tropism for forming pseudocysts in the brain tissue, spores with 7 or 8 equal shell valves and 7 or 8 polar capsules, spore size and the differences in the SSU and LSU rDNA sequence data relative to other kudoids. Kudoa chaetodoni was found in the lutjanids C. cuning and L. carponotatus, expanding the known host range for this species to include chaetodontids and lutjanids. L. ehrenbergii and L. fulviflamma were infected with Kudoa lethrini off Lizard Island, a parasite previously known only from lethrinids. Specimens putatively identified as Kudoa yasunagai from Liza vaigiensis and Lutjanus ehrenbergii were morphologically similar and genetically identical over the SSU rDNA dataset to previously reported specimens, but differed by 4 to 11 nucleotides over the LSU dataset from the remaining isolates examined here. While these data are not definitive, they suggest the presence of a K. yasunagai complex., (Crown Copyright © 2012. Published by Elsevier Ireland Ltd. All rights reserved.)

Thelohanellus kitauei Egusa et Nakajima, 1981, was described from common carp Cyprinus carpio L. in Japan. In China, a myxosporean infecting the intestinal tissue of the same host species was described as Thelohanellus xinyangensis Xie, Gong, Xiao, Guo, Li et Guo, 2000, despite many similarities to T. kitauei. To examine the potential conspecificity of these species, a morphological and molecular investigation of T. xinyangensis was conducted. Comparing myxospore morphology, the mean spore length and width of each species is not identical between species, but ranges of dimensions overlap. These data are more suggestive of intraspecific variation than distinct species. Comparison of relative ratios of spore length to polar capsule length and spore width to polar capsule width of T. xinyangensis and T. kitauei reveal no differences and scanning electron microscopy reveals a smooth spore surface of T. xinyangensis, which is consistent with that of T. kitauei. Most convincingly, DNA sequences of the small subunit ribosomal RNA (ssrRNA) gene of the two species were identical. From the morphological and molecular biological data, we propose T. xinyangensis from the intestine of common carp is not a distinct species and is synonymous with T. kitauei., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Kudoa prunusi n. sp. (Myxozoa; Multivalvulida) is described from the brain of Pacific bluefin tuna Thunnus orientalis cultured in Japan. Numerous white cysts, up to 0.5mm in size, were found on and in the brain. Spores having typically five spore valves and five polar capsules resembled a five-petal cherry blossom in apical view and were conical shape with a round bottom in side view. Average spore size was 9.63 (8.5-10.3) μm in width and 7.50 (6.7-8.6) μm in length. The spore dimensions of K. prunusi overlapped with those of Kudoa yasunagai ex Sillago ciliata having five to six spore valves, but they were clearly distinct in spore shape, 18S rDNA and 28S rDNA sequences (0.3% and 1.7% differences, respectively). Phylogenetic analysis of 18S rDNA revealed that K. prunusi grouped with the brain-infecting multivalvulid species, K. yasunagai, K. chaetodoni, K. lethrini and K. neurophila, rather than five-valved Kudoa spp. Combined with morphological, molecular and biological differences, K. prunusi was proven to be a new species., (Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.)

The myxozoan Zschokkella hildae Auerbach, 1910, was detected with a prevalence of 100% in cultured Atlantic cod, Gadus morhua L. aged 1+ from a culture facility on the west coast of Scotland. Sporogonic stages of Z. hildae, plasmodia producing 2-5 mature spores, were located predominantly in the collecting ducts and ureters of the kidney, and spores were present in the urine collected from the bladder. Less frequently, plasmodia were detected in the interstitial tissue of the kidney. The parasite prevalence in cultured fish was considerably higher than reported in wild fish but no obvious signs of pathology were detected. SSU rDNA sequencing and phylogenetic analysis showed that Z. hildae is closely related to a Sinuolinea sp. from the urinary system of turbot, Psetta maxima (L.), and that these two species, together with other myxozoans from the urinary system of marine fish cluster together in a sub-clade of the recognised marine clade of myxozoans. This sub-clade is characterised by a specific linear expansion segment, helix E23_15 in the secondary structure of variable region V4 of the SSU rDNA. Z. hildae and Sinuolinea sp. show extraordinary large linear expansion segment in both V4 and V7 and an important number of complementary base changes in the conservative regions of the SSU rDNA, indicating considerable evolutionary changes in the SSU rDNA of these species when compared with other myxozoans from the marine environment.

This paper describes the parasite Henneguya corruscans n. sp. which infects the gills of Pseudoplatystoma corruscans Spix and Agassiz, 1829 found in the Paraná River, Brazil. The parasites belong to the interlamellar-epithelial type as defined by Molnár (2002) [Molnár, K., 2002. Site preference of fish myxosporeans in the gills. Dis. Aquat. Org. 48, 197-207]. The spores examined had thin, smooth walls with symmetric valves; the total length of the spores was 27.6 (25-29)mum. The spore body was ellipsoidal in frontal view and biconvex in lateral view and they measured 14.3 (13-15)mum long by 5mum wide and 4mum in thickness. The polar capsules were small and elongated, equally sized, with a rounded posterior extremity and tapering anteriorly, and they corresponded more or less the half the length of the spore body; they were 6.8 (6-7)mum long by 2mum wide, and the polar filament formed 5-6 coils obliquely to the axis of the polar capsule. The tail was 13.7 (12-15)mum long and bifurcated shortly after the end of the spore body. The importance of the infection for the farming of P. corruscans is discussed.

Numerous pseudocysts of the myxosporean genus Kudoa were found infecting the body musculature of commercial frozen blocks of Patagonian hakes of the species Macruronus magellanicus, Merluccius australis, and Merluccius hubbsi. Pseudocysts consisted of numerous diminutive quadrate spores with four polar capsules. The small subunit ribosomal DNA was amplified, cloned, and sequenced for phylogenetic study. Minimum evolution and maximum parsimony analyses placed the resulting sequences in a clade with Kudoa species of Patagonian hakes, K. rosenbuschi and K. alliaria, with bootstrap values of 99%. Molecular and morphological results indicated that the above species were the same, with some differences based on host-related factors. Minor muscular damage appeared as a focal distortion of host fiber architecture to accommodate the parasite. The mild host response consisted of different stages of encapsulation. In cases of concurrent heavy infections, these fish are unappealing as food, due to the parasite's potential effect on the market's perception of macroscopic, unsightly cysts in fish musculature.

In this report, we describe Henneguya arapaima n. sp., a parasite of the gill arch and gall bladder of Arapaima gigas (pirarucu) collected in the Araguaia River, in the municipality of Nova Crixás, Goiás State, central Brazil. The plasmodia were white, round or ellipsoidal and measured 200-600 microm. Parasite development was asynchronous and the mature spores were fusiform and had smooth wall. The spores measurements were (range, with means+/-S.D. in parentheses): total length-48.4-53.1 microm (51.6+/-3.4 microm), body length-13.5-15.2 microm (14.2+/-0.8 microm), body width-5.1-6.1 microm (5.7+/-0.5 microm), body thickness-4.7-5.3 microm (4.9+/-0.2 microm) and caudal process length-38.0-41.2 microm (38.3+/-2.9 microm). The polar capsules were elongated and of unequal size, with lengths of 6.3-6.8 microm (6.5+/-0.2) and 6.2-6.6 microm (6.3+/-0.1) for the longest and shortest axes, respectively. Capsule width was 1.4-1.6 microm (1.5+/-0.1). Histological analysis showed that the plasmodia occurred in the tunica adventitia of the gall bladder and were delimited by a thin capsule of connective tissue. In the gill arch, the plasmodia were also surrounded by connective tissue similar to the endomesium of striated skeletal muscle cells. Sixty-five juvenile specimens of A. gigas weighing 1.0-25.0 kg were examined, 17 (26.1%) of which were infected. Of these, 14 (82.3%) had cysts in the gall bladder, two (11.7%) had cysts in the gill arch and only one (5.9%) had cysts in both organs. When the fish were grouped by weight, the prevalence of infection in fish weighing up to 10.0 kg (20.7%) was significantly lower than in fish weighing 10.1-25.0 kg (50%) (G=3.93; d.f.=1; p<0.05).