Kudoa azevedoi n. sp. (Myxozoa, Multivalvulida) from the oocytes of the Atlantic horse mackerel Trachurus trachurus (Perciformes, Carangidae) in Tunisian coasts

First report of Kudoa species (Myxozoa, Multivalvulida) infection in purple-spotted Bigeye (Priacanthus tayenus) from the Saudi Arabian Gulf

The purple-spotted bigeye, Priacanthus tayenus, is a marine benthic fish native to the Indian and Pacific Oceans, including the Arabian Gulf in Saudi Arabia. This study identified a myxozoan parasite infecting wild P. tayenus from the Saudi Arabian Gulf. These parasites produced spherical to ovoid-shaped, white plasmodia enclosed within pseudocysts in the fish musculature. The annual infection rate was 5.1%, with the highest prevalence in summer (7.6%), followed by spring (6%), and autumn (2.5%), while no infections were observed in winter. The number of plasmodia per fish ranged from 100 to 150 (135.1 ± 16.2). Their dimensions were 4-4.7 mm (4.3 ± 0.3 mm) in length and 4.5-7 mm (6 ± 1.1 mm) in width. Milky-colored exudates within the plasmodia contained mature spores measuring 8-9 μm (8.6 ± 0.4 μm) x 6-7.5 μm (6.9 ± 0.5 μm). The polar capsules of the spores exhibited dimensions of 2-5 μm (3.5 ± 0.5 μm) x 2.5-4.5 μm (3 ± 0.45 μm). Both morphological and genetic analyses confirmed these plasmodia as a novel Kudoa species. Histopathological examination revealed atrophy in the surrounding muscles without an inflammatory response. This study documents the first occurrence of a novel Kudoa sp. in P. tayenus at the Jubail landing site in Saudi Arabia, emphasizing the need for further surveillance and investigations to elucidate its pathogenesis and implications for wild fish stocks.

Morphological and molecular characterization of Chloromyxum dasyatidis n. sp. (Myxosporea: Chloromyxidae) in the common stingray Dasyatis pastinaca (Linnaeus) from Tunisian waters (Central Mediterranean Sea)

A new species of Chloromyxum Mingazzini, 1890, C. dasyatidis n. sp., is described from the gallbladder of the elasmobranch fish Dasyatis pastinaca (Linnaeus) from the Mediterranean coast off Tunisia. Mature myxospores were subspherical measuring 13.0 ± 0.3 (12.5-13.9) µm in length, 11.3 ± 0.5 (10.2-12.2) µm in width, and 11.8 ± 0.5 (11.4-12.7) µm in thickness. Four pyriform polar capsules 4.4 ± 0.3 (4.0-4.9) µm long and 3.5 ± 0.3 (3.0-3.8) µm wide. Valves were ornamented by 5 to 7 elevated surface ridges and displayed short caudal filaments. Chloromyxum dasyatidis n. sp. had an overall prevalence of infection of 38.5%, with significant seasonal variation, being more prevalent during summer (60.0%) and autumn (70.8%). Phylogenetically, this species grouped within the Chloromyxum sensu stricto lineage, forming a small clade together with the genetically more similar species C. acuminatum and C. myolibati, both from stingray hosts.

Four carangid fish species as new host records for Kudoa trachuri Matsukane, Sato, Tanaka, Kamata et Sugita-Konishi, 2011 (Myxozoa: Multivalvulida), and description of a new species, Kudoa longichorda sp. n., forming pseudocysts in the muscle of Decapterus tabl Berry

Multivalvulid myxosporeans of the genera Kudoa Meglitsch, 1947 and Unicapsula Davis, 1924 (Cnidaria: Myxozoa) are often the cause of unsightly cyst formation or postmortem myoliquefaction in the trunk muscle of commercial marine fish, which reduces the market value of infected individuals. Twenty species (18 Kudoa spp. and two Unicapsula spp.) have been recorded from carangid fish, although the majority of them, excluding polyxenous species, such as K. amamiensis Egusa et Nakajima, 1980, K. iwatai Egusa et Shiomitsu, 1983, K. nova Naidenova, 1975, K. quadratum (Thélohan, 1895) and K. yasunagai (Hsieh et Chen, 1984), are limited to a single or a few fish species. We report the occurrence of macroscopic cysts of Kudoa trachuri Matsukane, Sato, Tanaka, Kamata et Sugita-Konishi, 2011 in the trunk muscle of four new host fish species, i.e., Pseudocaranx dentex (Bloch et Schneider), Decapterus akaadsi Abe, D. muroadsi (Temminck et Schlegel) and Decapterus tabl Berry, fished from the Philippine Sea (Northwest Pacific Ocean), off southwestern of Japan. Myxospore morphology and genetic characteristics of the ribosomal RNA gene (rDNA) of these isolates were consistent with previous records of K. trachuri from Trachurus japonicus (Temminck et Schlegel) from around Japan. In addition, a new species of Kudoa that forms long filamentous pseudocysts in trunk myofibres was found in four of the six D. tabl collected in this study. We describe Kudoa longichorda sp. n. for this new isolate, based on its morphology of subquadrate myxospores with four shell valves and polar capsules and with small dimensions (length 4.3-5.5 µm, width 6.0-6.8 µm, thickness 4.8-6.3 µm, polar capsule length 2.3-3.1 µm, polar capsule width 1.1-1.7 µm), as well as 18S and 28S rDNA sequences distinct from those of known species.

Kudoa rousseauxii n. sp. (Cnidaria: Multivalvulida) Infects the Skeletal Muscles of the Freshwater Fish Brachyplatystoma rousseauxii in the Amazon River

PURPOSE

Members of the genus Kudoa Meglitsch, 1947 are known to infect the muscles of commercially important fishes worldwide, including those in the order Siluriformes. This paper describes the occurrence of a new species of Kudoa in the catfish Brachyplatystoma rousseauxii based on morphological study and molecular analysis of the ribosomal RNA gene (SSU rDNA).

METHODS

Fifteen specimens of Brachyplatystoma rousseauxii were purchased from fishing zones near Mosqueiro Island, Belém, Pará, Brazil. After necropsy, tissue samples and cysts were analyzed using a stereomicroscope, and fresh slides were viewed under a light microscope to confirm parasitic infection. The tissue fragments were removed and processed for molecular and histological analyses.

RESULTS

Microscopic pseudocysts were found in the epaxial region of skeletal muscle fibers in 80% of the analyzed specimens. The myxospores were quadrangular with four shell valves (SV), pyriform polar capsules (PC), and internal symmetry. Phylogenetic analyses indicated that the new species formed a cluster with the species previously described in the Amazon, being close to two freshwater species.

CONCLUSIONS

Morphological differences and molecular data of SSU rDNA support that Kudoa rousseauxii n. sp. is a new species that infects B. rousseauxii, a freshwater fish with intense migratory cycles that is widely captured and consumed in the Amazon.

Morphological Redescription and Phylogenetical Position of Ceratomyxa truncata Thelohan (1895) and Coccomyxa morovi Léger and Hesse, 1907 (Myxozoa: Myxosporea) Infecting the Gall Bladder of Sardina pilchardus (Walbaum) from Tunisian Coast

PURPOSE

Two myxosporean species have been, so far, independently reported from the gallbladder of the European pilchard, Sardina pilchardus (Walbaum) (synonym Clupea pilchardus) in the Northern shore of the Mediterranean Sea; Ceratomyxa truncata Thélohan, and Coccomyxa morovi Léger and Hesse, 1907. The two species were described with incomplete morphological data and based only on line drawings of their mature myxospores.

METHODS

During a parasitological survey in the Southern shores of the Mediterranean coast in the gulf of Gabès off Tunisia, two coelozoic myxosporean species were found in the European pilchard and described using morphological and molecular phylogenetic tools. Morphological characterization was based on the mature myxospore study and some vegetative stages. The SSU rDNA sequences were performed for molecular and phylogenetic study.

RESULTS

The most frequently encountered species belongs to the genus Ceratomyxa Thelohan, 1892. The second species belongs to the genus Coccomyxa. Morphological examinations, allowed us to match these two recorded species with Ceratomyxa truncata and Coccomyxa morovi, respectively, as previously described in the same host species referring to the original manuscripts instead of some morphological differences. Molecular analyses based on the partial SSU rDNA sequences did not much with any of the previously reported myxozoan sequences. Phylogenetic analysis positioned C. truncate in a well-supported clade including Ceratomyxa ssp. from Mediterranean Sea, while C. morovi was positioned on the basis of the subclade grouping all Coccomyxidae species.

CONCLUSION

We provided herein a first morphological redescription of Ceratomyxa truncata and Coccomyxa morovi parasite of Sardina pilchardus from the Southern shores of the Mediterranean Sea and we successfully obtained the SSU rDNA sequences of these two species and positioned them in the phylogenetic tree.

Utrastructure and molecular phylogeny of the myxozoan Kudoa ocellatus n. sp. (Myxozoa: Kudoidae), a parasite of the Oscar, Astronotus ocellatus (Agassiz, 1831; Teleostei: Cichlidae), a fish from northern Brazil

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.

Streptococcus, Centrocestus formosanus and Myxobolus tilapiae concurrent infections in farmed Nile tilapia (Oreochromis niloticus)

Stress triggered concurrent microbial/parasitic infections are prevalent in earthen pond based farmed Nile tilapia Oreochromis niloticus. In the current study, a total of thirty five O. niloticus were collected from a commercial fish farm with a history of severe mortalities at Port Said, Egypt. Nile tilapia samples were subjected to bacteriological, parasitological and pathological examinations. Twenty one Enterococcus fecalis and 15 Streptococcus agalactiae isolates were presumptively identified utilizing the semi-automated API 20 Strept test kit. The identities of the retrieved bacteria were confirmed by the sequencing of 16 S rRNA gene. Moribund O. niloticus were found to be heavily infected by one or both of Centrocestus formosanus encysted metacercariae (EMC) and/or Myxobolus tilapiae spores presenting a unique form of synergistic and/or symbiotic relationship. The identities of both parasites were confirmed through morphological and molecular characterization. Variable circulatory, degenerative, necrotic and proliferative changes were also noticed in hematopoietic organs. Interestingly, multiple myxobolus spores and EMC were noticed in some histological sections. It was obvious that the current concurrent bacterial and parasitic infections are triggered by the deleterious effects of some stressing environmental conditions. The unfavorable climatic conditions (high temperature and high relative humidity) recorded at the surge of mortalities are probable predisposing stress factors.

Negative impact on the reproductive potential of blue jack mackerel Trachurus picturatus by Kudoa infection of the ovary

Reproduction of Trachurus picturatus off the western Portuguese coast was studied over 1 yr. During histological analyses, the presence of Kudoa sp. was detected in advanced vitellogenic oocytes. Kudoa infections are known to cause economic loss through the induction of post-mortem liquefaction of fish muscles, but ovarian infection as reported in this study will seriously affect the reproductive potential of the species and thus impact fisheries productivity. Only females showed gonad infection which led to total degradation of advanced vitellogenic oocytes. No macroscopic, somatic or condition indices revealed differences between infected and uninfected females, rendering this infection event a concealed suppression of reproduction.

First report of Kudoa sp. in the palate and pharyngeal musculature of Gobioides grahamae Palmer and Wheeler, 1955 (Perciformes, Gobiidae) from Marajó Island, Brazil

ABSTRACT The aim of this study was to describe the first occurrence ofKudoasp. inGobioides grahamae, contributing to the understanding of this group of parasites in the Amazonian ichthyofauna. Forty specimens ofG. grahamaecollected from the natural environment were analyzed. Cysts ofKudoasp. were diffusely distributed through the striated skeletal muscle fibers with severe edema and inflammatory infiltrate composed of lymphocytes were observed in 30% of the specimens. Edema and marked coagulation necrosis of the muscle fibers was associated with infection byKudoasp. spores, which had accumulated inside the skeletal muscle fibers. Although there are no records of foodborne outbreaks caused by Kudoa spp. in Brazil, it is of paramount importance that we evaluate its occurrence, since the consumption of fish, especially raw fish, has increased because of the adoption of Japanese cuisine. To minimize the economic impacts on the fisheries market and the risk of this parasite to public health, it is necessary to initiate a program to monitor the presence of this likely underdiagnosed, emerging parasite.

Morphological and molecular characterization of Ceratomyxa batam n. sp. (Myxozoa: Ceratomyxidae) infecting the gallbladder of the cultured Trachinotus ovatus (Perciformes: Carangidae) in Batam Island, Indonesia

A new coelozoic myxozoan species, Ceratomyxa batam n. sp., was identified in cultured carangid fish, Trachinotus ovatus (Perciformes: Carangidae), in waters off Batam Island of Indonesia. The bi- and trivalved spores were observed in the gallbladder of T. ovatus. Mature bivalved spores of C. batam n. sp. were transversely elongated and narrowly crescent in shape, 3.8 ± 0.36 (2.7-4.6) μm long and 19.2 ± 1.75 (16.2-22.0) μm thick. Two sub-spherical polar capsules were 2.3 ± 0.18 (2.0-2.8) μm long and 2.6 ± 0.16 (2.3-2.9) μm wide. Prevalence was 72.2% in 72 examined T. ovatus according to evaluations dating from November 2016. The maximum likelihood phylogenetic tree based on small subunit rDNA sequence showed similarity with Ceratomyxa robertsthomsoni and Ceratomyxa thalassomae found in Australia. This is the first report of Ceratomyxa species identified in a seawater fish at Batam Island, Indonesia.

Morphological and molecular identification of a new Kudoa thyrsites isolate in Mediterranean silver scabbardfish Lepidopus caudatus

Myxozoans of the genus Kudoa (Myxosporea, Multivalvulida) infect marine and estuarine fish species worldwide. Some Kudoa species are of concern to the seafood industry since they may generate macroscopic cysts in the fish host's musculature, or cause post mortem myoliquefaction, commonly known as 'soft flesh'. One of the economically most important species is K. thyrsites, a myoliquefactive myxosporean parasite that occurs in many wild and cultured marine fish species worldwide. Here we identified a K. thyrsites isolate as the causative agent of myoliquefaction in silver scabbardfish Lepidopus caudatus from the Alboran Sea (western Mediterranean Sea). For comparative and validation purposes, the morphological and molecular characteristics of the isolate were compared with fresh spores of a K. thyrsites isolate infecting Atlantic mackerel Scomber scombrus from the Norwegian Sea. Myxospores of both isolates shared a stellate appearance and contained 4 unequal pyriform polar capsules (1 large, 1 small and 2 intermediate). These morphological traits were consistent with all other previously described K. thyrsites isolates. Moreover, the small subunit rDNA sequences of the Mediterranean and Norwegian Sea isolates revealed 100% similarity, and matched 100% with K. thyrsites isolates previously recorded in myoliquefactive Atlantic mackerel from the North Sea and off southern England. The findings suggest that K. thyrsites is the primary cause of myoliquefaction in silver scabbardfish from the Alboran Sea. This report represents the first morphological and molecular characterization of K. thyrsites in the Mediterranean Sea. A set of new allometric characters is proposed as additional descriptors for more accurate and specific description of kudoid myxospores.

Myxobolus sp. and Henneguya sp. (Cnidaria: Myxobolidae) natural co-infection in the kidney of Piaractus mesopotamicus (Characiformes: Serrasalmidae)

This study evaluated the myxozoan infection and histopathology of the kidney of freshwater fish Piaractus mesopotamicus from intensive fish farming in Brazil. A total of 55 fish were examined for myxozoan infection. Infected organs were processed by usual histology and stained with hematoxylin-eosin (H&E) and Ziehl-Neelsen (ZN). From the total of 55 fish analyzed, 47 (85.45%) presented myxospores, being 9.09% (5/55) only with Myxobolus sp., 5.45% (3/55) only with Henneguya sp., and 70.91% (39/55) presenting both parasites. The presence of myxospores was associated with histological alterations in both stromal and renal parenchyma. Myxospores were found mostly in the peritubular interstitial tissue and in low intensity in the glomerulus which caused nuclear hypertrophy and loss of Bowman space. An increase in the glomerular tuft and a reduction in the lumen of the collector tubules were also observed, besides the high number of melanomacrophage cells in the glomerulus. This study reports for the first time detection of myxozoan mixed infection in one organ of pacu and discuss the possible transportation of myxospores in the circulating blood.

Immune response of olive flounder (Paralichthys olivaceus) infected with the myxosporean parasite Kudoa septempunctata

This study evaluated the pathophysiological, biochemical, and immunological status of olive flounder (Paralichthys olivaceus) infected with the myxosporean parasite Kudoa septempunctata. Flounder fish collected from Kudoa-infected and uninfected farms were confirmed by microscopic and TaqMan probe-based quantitative PCR screening. Morphological, biochemical, histological, and immune gene expression analyses were performed on uninfected and infected hosts to assess the effect of K. septempunctata. Histological studies confirmed the presence of Kudoa myxospores in the trunk muscles of infected flounder fish. Serum biochemical parameters, including the levels of myeloperoxidase activity, superoxide dismutase activity, alanine aminotransferase, alkaline phosphatase, amylase, bilirubin, total protein, cholesterol, calcium, potassium, sodium, phosphorus, glucose, and galactose, were found to exhibit no significant variations (p > 0.05) between uninfected and infected flounder fish. However, immune-related genes such as Mx, lysozyme, signal transducer and activator of transcription 1, interferon-γ, interferon regulatory factor, and tumour necrosis factor showed significantly elevated expression (p < 0.05) in the trunk muscles of infected flounder fish while no significant differences were noted in uninfected fish trunk muscle and head-kidney of infected and uninfected flounder fish.

Effects of Kudoa septempunctata genotype ST3 isolate from Korea on ddY suckling mice

This study investigated the effects of Kudoa septempunctata genotype ST3 spores on ddY suckling mice. Purified Kudoa septempunctata spores were administered into the stomachs of the mice at 5 × 10(6) or 5 × 10(7) spores/mouse, with inactivated Kudoa (5 × 10(6) spores/mouse) or vehicle as controls. No abnormal clinical symptoms were observed and there were no variations in fluid accumulation ratio and cytokine gene expression in all groups. In addition, intact Kudoa spores and the 18S rDNA gene were only detected (by microscopy and quantitative PCR, respectively) in the groups administered such spores. This study thus confirms that spores from the ST3 strain of Kudoa septempunctata were excreted in the faeces without infecting the gastrointestinal tract in ddY suckling mice.

Ultrastructure and phylogeny of Kudoa barracudai sp. nov. infecting Sphyraena putnamae in the Red Sea

Kudoa barracudai n. sp. has been found infecting the muscles of Sphyraena putnamae from Red Sea, Saudi Arabia. The prevalence of the infection was 10 % (5/50). Its ovoidal plasmodia encapsulated with fibrous connective tissue and measuring 700 × 510 μm. Local myolysis was observed around the plasmodia without inflammatory reaction. Mature spores were quadrate in the apical view with rounded edges and subspherical to ovoid in the side view and measured 5 μm (4.5-5.5) in width and 5.5 μm (5-6) in thickness. Polar capsules were pyriform, equal in size, and measured 2.5 μm (2-3) in length and 1.5 μm (1-2) in width with two filament coils. Ultrastructural analysis showed a demarcated border between the parasite cellular mass and host cellular components that represented the cyst wall, and cysts were filled with mostly mature spores. Phylogenetic analysis of the small subunit ribosomal RNA (SSU rRNA) using the maximum likelihood and Bayesian inference approaches showed the new species clustered in a robust clade with Kudoa amamiensis, Kudoa kenti, and Kudoa quraishii. The SSU rRNA gene of K. barracudai was most similar to K. amamiensis (98.7 %), followed by K. kenti (97.4 %) and K. quraishii (96.6 %). This combination of morphological data and molecular analysis served to identify this parasite as a new species of Kudoa, which we have named K. barracudai n. sp.

Ceratomyxa tunisiensis n. sp. (Myxosporea: Bivalvulida) from the Gallbladders of Two Carangid Fish Caught Off the Coast of Tunisia

A new coelozoic Myxozoan species, Ceratomyxa tunisiensis n. sp., was found infecting the gallbladders of two carangid fish, Caranx rhonchus and Trachurus trachurus (Perciforme, Carangidae), from the Gulf of Gabès, on the southern coast of Tunisia. The parasite develops in spherical mono-, diplo-, or polysporic tropozoites in the gallbladder of the hosts. Mature spores are typical of the genus Ceratomyxa. They are transversely elongated and narrowly crescent-shaped with a slightly convex anterior and concave posterior, and measure 23 ± 0. 27 (20-25) μm width × 6 ± 0.26 (5-8) μm in length. Spore shell valves are symmetrical with rounded ends. Two spherical polar capsules situated on either side of the sutural line measure 2.2 μm (2.0-3.0) in diam. Periodical sampling of C. rhonchus and T. trachurus from Marsh 2012 to February 2013 showed that infection due to C. tunisiensis occurs in 59% and 69% of the examined fish, respectively. Molecular analysis based on the small subunit (SSU) rRNA sequence shows high genetic divergence with all other ceratomyxid species. A Maximum Likelihood phylogenetic tree shows association with the species C. leatharjecketi Fiala, kova, Kodadkova, Freeman, Bartošova-Sojkova, and Atkinson, 2015 reported from the gallbladder of Aluterusmonoceros (L.) caught in the Andaman Sea, off Malaysia. Nonetheless, the SSU rRNA sequences of C. tunisiensis and C. leatharjecketi have only a 90% similarity.

Morphological and molecular aspects of Ceratomyxa mehlhorni n. sp., a parasite of the golden trevally Gnathanodon speciosus in the Arabian Gulf off the Saudi Arabian coast, with data on its seasonal prevalence

During a survey of the myxosporean fauna of the golden trevally Gnathanodon speciosus from the Arabian Gulf off Saudi Arabia, a species of Ceratomyxa that did not conform to any known species was recorded. The infection was detected as a large number of mature spores free-floating in the bile. Mature spores were hat- or helm-like in the frontal view with two short and unequal valves. The spores measured 8 (7-9) × 12 (10-14). The two polar capsules were spherical, equal in size and measured 3 (2-4) in diameter with three filament turns. Sporoplasm was binucleated and filled the whole extracapsular space. The small subunit ribosomal DNA sequence of this species did not match any available sequences in GenBank. The lowest genetic distance was 0.017, observed with Ceratomyxa moseri infecting Pomacentrus wardi from Australia's Great Barrier Reef. A maximum likelihood phylogenetic tree showed a close association between the new species and a variety of ceratomyxid species, including Ceratomyxa arabica reported from the Arabian Gulf. Given the morphological and molecular differences between this species and other Ceratomyxa spp., we proposed the present form was a new species and the name Ceratomyxa mehlhorni sp. n. for this parasite from the gallbladder of G. speciosus.

Kudoa spp. (Myxozoa) infection in musculature of Plagioscion squamosissimus (Sciaenidae) in the Amazon region, Brazil

Ninety specimens of Plagioscion squamosissimus captured using fishing tackle in the Outeiro district, state of Pará, were examined. Fish were placed in plastic bags containing water, under conditions of artificial aeration, and transported live to the Carlos Azevedo Research Laboratory (LPCA), in Belém, Pará. They were anesthetized, euthanized and necropsied; small fragments of the epaxial and hypaxial muscles were removed for examination of fresh histological sections by means of optical microscopy. In 100% of the specimens analyzed, parasitic pseudocysts were seen to be interspersed within and between the skeletal muscle. These contained pseudoquadrate and/or star-shaped spores that presented four valves and four polar capsules, which were identified from their morphology as belonging to the genus Kudoa. This is the first report of Kudoa in P. squamosissimus in the Amazon region, Pará, Brazil.

A new record of Myxobolus brachysporus and M. israelensis in the tilapia (Oreochromis niloticus) collected from the Nile River, Egypt

The present study was carried out as part of an ongoing general survey for myxosporean parasites infecting tilapias in the River Nile, Egypt. In the present study, 77 Nile tilapia (Oreochromis niloticus) were collected from boat landing sites at Beni-Suef governorate, Egypt and examined for the myxosporean infection. The infection was encountered as a huge number of free spores in the kidney and the spleen. The infection showed a prevalence of 51.9% (40/77) for Myxobolus brachysporus while it was 25.9% (20/77) for Myxobolus israelensis. Mature spores of M. brachysporus were ellipsoidal and measured 8.6 × 13.2 μm. The polar capsules were subcircular with 5–6 filament turns and measured 4.7 × 3.6 μm. Spores of M. israelensis were ellipsoidal in the frontal view and fusiform in the lateral view. Spore measurements were 13.4 μm long and 8.7 μm wide. The polar capsules were elongated with 6–7 filament coils and measured 8.6 × 3.1 μm. The findings presented here proved that tilapia fishes in the Nile River are still suffering from infections with Myxobolus species. Therefore, further studies should be carried out to survey the Myxobolus infection among tilapias under culture conditions to clarify the pathological impacts of this parasite in tilapias aquaculture.

Morphology, phylogeny and seasonal prevalence of Ceratomyxa arabica n. sp. (Myxozoa: Myxosporea) infecting the gallbladder of Acanthopagrus bifasciatus (Pisces: Sparidae) from the Arabian Gulf, Saudi Arabia

A new myxozoan species was recovered from the gallbladder of Acanthopagrus bifasciatus from the Arabian Gulf in Saudi Arabia. The overall prevalence of infection was 28.6 % (32/112), with the highest prevalence 42.9 % (12/28) in winter and 10.7 % (3/28) as the lowest in autumn. The new species is described using its morphological characteristics and small subunit (SSU) rDNA. Spores of Ceratomyxa arabica n. sp. are stubby-shaped with unequal shell valves, 8 (7-9) μm in length × 12 (10-14) μm in thickness. Polar capsules are sub-spherical, unequal, 3 (2.5-3.5) × 2 (1.5-2.5) μm. The polar filament has three turns and is slightly slanted towards the longitudinal axis of the capsules. The small subunit rDNA (SSU rDNA) sequence confirms that the present species is a member of the genus Ceratomyxa, being most closely related to Ceratomyxa cardinalis with a sequence similarity of 97.77 %.

Molecular and morphometric characteristics of Ceratomyxa hamour n. sp. (Myxosporea: Bivalvulida) infecting the gallbladder of the orange-spotted grouper Epinephelus coioides from the Arabian Gulf, Saudi Arabia

Ceratomyxa hamour n. sp. was found to infect the gallbladder of the orange-spotted grouper, Epinephelus coioides located off the Saudi Arabian coast of the Arabian Gulf. The infection was reported as a free-floating spore in the bile, and pseudoplasmodia were not observed. Mature spores were crescent-shaped and measured on average 7 μm in length and 16 μm in thickness. The polar capsule, meanwhile, had length to width measurements of 4 μm and 3 μm on average. A periodical survey was conducted throughout a sampling period between December 2012 and December 2013, with the results showing that the parasite was present throughout the year with a mean prevalence of 32.6%. The objective of this study was to characterize this new species based on its morphological and molecular differences from previously described species. Molecular analysis based on the partial sequence of the SSU rDNA gene, showed the highest similarity (97.8%) to Ceratomyxa buri, reported in the cultured yellow tail Seriola quinqueradiata in Japan. Indeed, C. buri and the new species described here formed an individual cluster with a high degree of bootstrap support. This is the first reported species of genus Ceratomyxa from the Arabian Gulf fishes off Saudi Arabia.

Negative effects of Kudoa islandica n. sp. (Myxosporea: Kudoidae) on aquaculture and wild fisheries in Iceland

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A novel myxosporean species, Kudoa islandica, is described.

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It is prevalent in lumpfish and Atlantic and spotted wolffish.

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It causes extensive post mortem myoliquefaction.

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It was a major factor in the closure of spotted wolffish farming in Iceland.

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It infects fish from different taxonomic orders and could be a concern in aquaculture.

In the early 2000s, experimental rearing of spotted wolffish, Anarhichas minor, was started in Iceland. Health surveillance, carried out at regular intervals during the rearing period, revealed persistent and highly prevalent Kudoa infections of fish muscles which caused great financial losses due to post mortem myoliquefaction. In addition, during the traditional process of drying and smoking wild Atlantic lumpfish, Cyclopterus lumpus, the muscles from some fish almost completely disappear and the fish have to be discarded.

To describe the etiological agent responsible for these conditions, spotted wolffish, Atlantic wolffish Anarhichas lupus, northern wolffish Anarhichas denticulatus and Atlantic lumpfish were caught off the Icelandic coast and examined for the presence of Kudoa. We describe a novel myxosporean, Kudoa islandica n. sp., using morphological and molecular data, and show with histopathology that it causes extensive myoliquefaction in three different wild fish hosts, which all are commercially valuable species in Iceland. Although some spore dimensions varied significantly between fish species, the molecular analyses showed that the same parasite was responsible for infection in all fish. The northern wolffish was not found to be infected. Although robustly placed in the Kudoa clade in phylogenetic analyses, K. islandica was phylogenetically distinct from other kudoids.

A single myxosporean, K. islandica, is responsible for the infections in the somatic muscles of lumpfish and wolffish, causing extensive post mortem myoliquefaction. This myxosporean is likely to infect other fish species and it is important to study its life cycle in order to evaluate any threat to salmonid culture via the use of lumpfish as a biocontrol for sea lice.

Structural and molecular characterization of Kudoa quraishii n. sp. from the trunk muscle of the Indian mackerel Rastrelliger kanagurta (Perciforme, Scombridae) in Saudi Arabia coasts

A new Myxozoa, Kudoa quraishii n. sp., is reported in the striated muscle of the Indian mackerel Rastrelliger kanagurta from the Red Sea and the Arabian Gulf in Saudi Arabia. Mean prevalence of infection is about 20% and varies between localities. The parasite develops whitish and oval or rounded pseudocysts of 0.2-3 mm in the striated muscles of the body. Pseudocysts are filled with mature spores. Myxospores are quadrate in shape in apical view with rounded edges and ovoid in side view. Each spore is formed by four equal shell valves and four symmetrical polar capsules. Polar capsules are pyriform in apical view and drop-like in side view. Myxospore measurements in micrometers are 6.14 (5.9-6.34) in width, 5.48 (5.3-5.71) in thickness, and 4.27 (4.1-4.42) in length. Polar capsule measurements in apical view in micrometers are 2.08 (1.88-2.28) and 1.31 (1.10-1.52) length by width. Molecular analysis based on SSU rDNA gene shows closest association with K. amamiensis and K. kenti with respectively 98 and 97.2% of similarities.

Synopsis of the species of Kudoa Meglitsch, 1947 (Myxozoa: Myxosporea: Multivalvulida)

A synopsis of the species of Kudoa Meglitsch, 1947 (Myxozoa, Myxosporea, Multivalvulida) is presented, including 95 nominal species. For each species the most relevant morphological and morphometric features are indicated in tabulated format. Included are data on the site of infection within the host, the type-host and type-locality, plus a full bibliography of the original records for these species. Molecular data (GenBank accession numbers) are also provided whenever possible.

Unicapsula species (Myxosporea: Trilosporidae) of Australian marine fishes, including the description of Unicapsula andersenae n. sp. in five teleost families off Queensland, Australia

A survey of the myxosporean fauna of Australian marine fishes revealed the presence of three previously unreported species of Unicapsula (Multivalvulida: Trilosporidae) from sites off Southeast Queensland, off Lizard Island on the Great Barrier Reef, Queensland, and from Jurien Bay in Western Australia. Morphometric data (spore, polar capsule and caudal appendage dimensions) combined with Bayesian inference and maximum likelihood analyses of small subunit (SSU) and large subunit (LSU) ribosomal DNA (rDNA) were used for species identification and to explore relationships among these taxa. The four species of Unicapsula for which DNA data are now available for comparative purposes (Unicapsula andersenae n. sp., Unicapsula pflugfelderi, Unicapsula seriolae and Unicapsula pyramidata) formed a well-supported monophyletic sister clade to the other major multivalvulidan group, the Kudoidae. The combined morphometric and genetic diagnostic approach identified an undescribed taxon, U. andersenae n. sp., from the muscle of Argyrosomus japonicus, Acanthopagrus australis and Eleutheronema tetradactylum off the Southeast Queensland coast and in Lutjanus russellii and Sillago ciliata off Lizard Island. Intra-specific variation within U. andersenae n. sp. varied from 2-4 (0.2-0.4%) nucleotides over the SSU region to 2-20 (0.3-3.2%) over the LSU region. Inter-specific variation between U. andersenae n. sp. and the other three species for which genetic sequence data are now available ranged from 15-66 (3-6.5%) nucleotides over the SSU region to 103-120 (17.6-21.2%) nucleotides over the LSU region. The host distribution observed here for U. andersenae n. sp. (five fish species from five different fish families) represents the broadest specificity known for a single species of Unicapsula. U. pyramidata Naidjenova & Zaika 1970, whose spore morphology and presence of caudal appendages immediately distinguish it from other species, was recovered from the nemipterid, Scolopsis monogramma, off Lizard Island. U. seriolae Lester 1982 is reported here from Yellowtail Kingfish, Seriola lalandi, from sites off Queensland and from Jurien Bay, Western Australia. Comparative genetic analyses also revealed that an unidentified species of Unicapsula from Epinephelus septemfasciatus off Japan whose rDNA sequence data are available on GenBank is consistent with U. seriolae. This suggests that U. seriolae may also exhibit low host specificity and may be distributed widely throughout the Indo-West Pacific region. In comparison to other myxozoan genera, it is clear that the species richness of Unicapsula spp. falls well below that displayed by either Ceratomyxa spp. or Kudoa spp. The discovery of a further new species of Unicapsula in Australia now brings the total worldwide number of formally described Unicapsula species to a modest 11. Nonetheless, this taxon remains of significant interest to commercial and recreational fisheries through the potential production of macroscopic pseudocysts in fish muscle and post-mortem muscle liquefaction, both of which can render fish fillets unpalatable and unmarketable.