Myxosporean Species Research Articles

Ceratomyxa azevedoi n. sp. (Myxozoa: Myxosporea) parasitizing the gallbladder of Lutjanus ehrenbergii in the Arabian Gulf.

A novel myxosporean species, Ceratomyxa azevedoi sp. n. is described from the gallbladder of the blackspot snapper, Lutjanus ehrenbergii (Peters), captured from the Arabian Gulf off Saudi Arabia. A total of 45 (26.8%) out of 168 fish specimens were found to be infected with Ceratomyxa azevedoi sp. n., the highest prevalence being observed in winter (42.9%, 18/42) and the lowest in autumn (11.9%, 5/42). Mature spores appeared as crescent to slightly elliptical-shaped, measuring 5-7 (6) μm in length and 12 (10-14) μm in thickness, with spherical polar capsules containing three polar filament coils. The morphometric and morphological comparison with similar species revealed the taxonomic novelty of this form, suggesting that it should be considered as new species. The phylogenetic analysis of C. azevedoi sp. n., based on partial SSU rDNA sequences, revealed close genetic relatedness to C. buri with 91.3% homogeneity and to C. hamour, with 90.1% homogeneity.

Parasitological and histological analysis of a new species of the genus Thalohanellus and description of a myxozoan parasite (Myxosporea: Bivalvulida) from cultured ornamental goldfish, Carassius auratus L.

An ornamental fish parasitological survey of West Bengal, India during the year 2014–16 revealed that goldfish, Carassius auratus, was the most susceptible species for myxozoan infestation. This communication revealed the presence of two myxosporean species belonging to the genera Myxobolus and Thelohanellus. Although myxozoan infestation has been determined by isolating small to large, spherical to ellipsoidal plasmodia up to 0.5–2.5mm were filled with disporic pansporoblasts and mature spores. M. ichkeulensis and one new species T. dipaki n. sp. have been isolated infecting the ornamental goldfish (Carassius auratus) for the first time in India. In the present study, new host, and new locality for M. ichkeulensis have been reported. The description of M. ichkeulensis is being considered as a first report from India. Spore of T. dipaki n. sp. measures uniquely 13.99±0.60×9.82±0.60μm in size, having a one globular pyriform polar capsule measuring 7.45±0.62×5.91±0.39μm. The severity of newly isolated myxozoan infestation has also been assessed by the histopathological changes of fins of the hostfish. A combination of light and scanning electron microscopic observation along with its severity of infestation, comparison of same and closely related species has been incorporated to identify the new species. The paper deals with the diversity, distribution and taxonomic descriptions of new and known myxozoan species along with new host, locality records and incidence of infestation.

Myxosporea (Cnidaria : Myxozoa) infecting the saddled seabream Oblada melanura (L. 1758) (Teleostei : Sparidae) and the painted comber Serranus scriba(L. 1758) (Teleostei : Serranidae) in Tunisia.

First parasitological surveys of Myxozoa are performed on the sparid saddled seabream Oblada melanura (Linnaeus, 1758) and the serranid painted comber Serranus scriba (Linnaeus, 1758) caught from the Bay of Bizerte and the Gulf of Tunis respectively in Northeast Tunisia, Western Mediterranean. In this study, 6 bivalvulid myxosporean species belonging to the 3 genera Ceratomyxa Thélohan, 1892, Myxodavisia Zhao, Zhou, Kent & Whipps, 2008 and Zschokkella Auerbach, 1910, are isolated infecting their hosts. Two species Ceratomyxa sp. 1 ex O. melanura (Prevalence (P) = 36%) and Ceratomyxa sp. 2 ex O. melanura (P = 13%) infected the saddled seabream and four species Ceratomyxa sp. 1 ex S. scriba (P = 11.7%), Ceratomyxa sp. 2 ex S. scriba (P = 6.7%), Myxodavisia sp. (P = 8.3%) and Zschokkella sp. (P = 5.6%) infected the painted comber. These myxosporeans differ, in vegetative stages and/or in mature spores, from all the previously known congeneric species, and are described here on the basis of their morphological and morphometric features, their host and tissue specificities and their biogeographical distribution. This is the first report of myxosporean infections in O. melanura and S. scriba. The occurrence of two ceratomyxid species in each host species supports that the genus Ceratomyxa is host-specific not only in sparids but also in serranids, which agrees with data previously obtained from Sparidae in Mediterranean Sea and from Serranidae in GBR, Australia. A member of the myxosporean genus Myxodavisia is recorded from the Mediterranean Sea for the first time, and Zschokkella spp. infections have not previously been recorded from a host in Serranidae. During the examination, a several cases of Co-infection among myxosporeans, both with two and three species, are provided and statistically studied. Indeed, 5% of the breams and 9.4% of the combers are infected with more than one myxosporean parasite. The relationship between myxosporean infections and some biological parameters are pointed out. A higher prevalence of myxosporean infection is coincided with the peak period of spawning activity in May-June for S. scriba. For both hosts, analysis using Fulton's condition factor (K) has revealed no significant difference between infected and non-infected fishes. Clinically, no external signs of disease have been occurred in infected hosts, but some changes in the bile fluid, colour, and viscosity and in the gall bladder 's tissue are examined in S. scriba.

Morphological re-description and phylogenetic relationship of five myxosporean species of the family Myxobolidae infecting Nile tilapia.

Freshwater fish have a major economic and nutritional importance worldwide. Myxosporeans are highly dangerous parasites that infect different fish species, causing severe damage to a large number of economically important species, especially in aquaculture. We conducted a survey of myxosporean parasites infecting Nile tilapia Oreochromis niloticus (Perciformes: Cichlidae) collected from different localities along the River Nile passing through Giza province, Egypt. Out of 100 fish specimens collected, 45 were found to be naturally infected with these parasites in the region of the trunk kidney. Light microscopic examination revealed the presence of 5 distinct myxosporean species belonging to 2 different genera, viz. Myxobolus and Triangula, belonging to the family Myxobolidae; all 5 species have been previously described. Morphological characteristics, host specificity and geographical distribution, tissue tropism, and molecular analysis of the partial sequence of small subunit ribosomal DNA gene revealed that the recovered myxosporean species described herein were genetically distinct from other myxozoan species but had 95% sequence similarity to M. cerebralis. Also, phylogenetic analysis placed the present myxosporean species in the freshwater Myxobolus clade, which is a sister group of freshwater Myxobolus/Henneguya species.

A new Myxidium species (Myxozoa: Myxosporea) infecting the gallbladder of the turtle Podocnemis unifilis (Testudines: Podocnemididae) from Peruvian Amazon

A new myxosporean species, Myxidium peruviensis n. sp., is described parasitizing the gall bladder of the yellow-spotted river turtle Podocnemis unifilis kept in captivity in an Amazonian Peruvian turtle rescue unit in the city of Iquitos, State of Loreto, Peru. The parasite was found in four of ten (40%) P. unifilis examined. The new species was characterized based on morphological and molecular phylogeny analyses. SSU rDNA sequence of the spores of M. peruviensis n. sp. resulted in 1876 nucleotides and this sequence did no match any of the Myxozoa available in the GenBank. Phylogenetic analysis identified the new species as a sister species of Myxidium turturibus, the unique Myxidium species described in a Neotropical turtle. Nevertheless, the SSU rDNA sequences of the new species and M. turturibus have only a 91.5% similarity. This is the first description and molecular study of a Myxozoa in a reptile from Peru. Considering the status of P. unifilis as vulnerable species, the infection by Myxidium parasites is emphasized as possible disease impeller, representing menace to the turtle conservation.

Development of a multiplex PCR method for the simultaneous detection of four myxosporeans infecting gibel carp Carassius auratus gibelio.

Gibel carp Carassius auratus gibelio (Bloch), a commercially important freshwater-cultured fish in China, is threatened by myxosporeans, particularly Thelohanellus wuhanensis, Myxobolus honghuensis, M. wulii and M. turpisrotundus. Here, we developed a multiplex PCR assay for simultaneous detection of these 4 myxosporeans. The specific primers for each species were designed based on the 28S rDNA gene of T. wuhanensis, the ITS-5.8S rDNA of M. honghuensis and M. wulii, and the 18S rDNA gene of M. turpisrotundus. Specificity testing confirmed that the 4 primer sets have no cross-reactivity with other related myxosporean species tested. Detection limits of the multiplex PCR assay were 0.2, 0.3, 3.1 and 3.8 spores for T. wuhanensis, M. honghuensis, M. wulii and M. turpisrotundus, respectively. Following screening of 104 field samples, the analytical sensitivity of the present multiplex PCR assay was found to be similar to the sensitivity obtained by the singleplex PCR assays and was higher than that of microscopic examination. Moreover, Kappa analysis showed a strong agreement between the results of the singleplex and multiplex PCR assays, indicating that the developed multiplex PCR assay was an efficient approach for the diagnosis of the 4 myxosporeans infecting gibel carp.

Redescription and Histopathology of Two Species of Myxozoans Infecting Gills of Fingerlings of Indian Major Carps

During the present study, two myxosporean species, M. potularis Madhavan et al. (2013) and M. rocatlae Basu and Haldar (2002) have been described from the gills of Labeo rohita Hamilton vern. rohu and Cirrhinus mrigala Hamilton vern. mrigal at nursery ponds located in village Fagan majra, District Fategarh Sahib, Punjab, India. Earlier, both the species M. potularis and M. rocatlae were described from West Bengal. 30 speciemens of Labeo rohita and 40 specimens of Cirrhinus mrigala were examined. Out of which 23 and 21 fishes were infected respectively. The prevalence rate was more in M. potularis (76.66%) than M. rocatlae (52.5%). At the time of collection various physico-chemical parameters like temperature, pH, TDS, DO etc. were also recorded. The histological effects of the pathogen were observed by light microscopy. The plasmodia of M. potularis were located in the afferent artery of the gill filament and plasmodia of M. rocatlae were located in the fine blood capillaries at the tip of the gill lamellae. M. potularis was highly pathogenic than M. rocatlae. The plasmodia of M. potularis were typed in “D” category caused complete destruction of all the cellular elements of gills and caused inflammation and abscesses. When present in large number and regarded as highly pathogenic parasite infects fingerlings in aquaculture. The gill plasmodial index (GPI) was 4 for M. potularis n. sp. indicated severe infection and 1 for M. rocatlae indicated light infection.

Ultrastructural, ssrDNA sequencing of Myxobolus prochilodus and Myxobolus porofilus and details of the interaction with the host Prochilodus lineatus.

Myxobolus prochilodus and Myxobolus porofilus are parasites of Prochilodus lineatus, an economically important South American fish found in La Plata and Paraiba do Sul river basins. This study focusing on parasite-host interaction provides an ultrastructural and phylogenetic analysis, the latter based on ssrDNA sequencing of these parasites respectively infecting the gill filaments and fins of P. lineatus taken from the Mogi Guaçu River, São Paulo, Brazil. A total of 13 adult specimens were examined in this study. The prevalence of infection was 7.69% for M. prochilodus and 15.38% for M. porofilus. Phylogenetic analysis showed M. prochilodus and M. porofilus clustered in a subclade composed of parasites of the Prochilodontidae family. In M. prochilodus infecting gill filaments, where cellular degeneration in the epithelium was observed, the plasmodia were surrounded by a capsule composed of layers of fibrocyte-like cells, with cellular projections joined to the projections of other fibrocyte-like cells by desmosomes, and more externally typical fibroblast layers. Some granular leukocytes were seen interspersed among these layers. In M. porofilus infecting the fins, the capsule of connective tissue was represented only by loosely arranged collagen fibers, and no granular leucocytes were observed. Finally, several unusual vacuoles with filamentous content and some characteristics usually described as degenerative alterations, as myelin figure, were noted in plasmodia and pansporoblasts of both myxosporean species. The possible influence of inflammatory response and xenobiotics was considered to be the explanation for the alterations observed in Myxobolus species and its host.

Morphological description and phylogeny of Ceratomyxa scorpaeni n. sp. (Myxosporea: Ceratomyxidae) infecting the gallbladder of Scorpaena porcus (L.) (Scorpaeniformes: Scorpaenidae) from the bay of Bizerte in Tunisia.

A new marine myxosporean species Ceratomyxa scorpaeni n. sp. is described using morphological characteristics and small subunit ribosomal DNA (rDNA) sequence data. The parasite was found infecting the gallbladder of Scorpaena porcus Linnaeus, 1758 collected from the Bay of Bizerte. Mature plasmodia were disporous free floating in the bile. Spores were transversely elongated and crescent-shaped with unequal shell valves and measured 7.6 ± 0.2 (7.2-8.0) μm in length and 32.8 ± 0.3 (21.6-44.0) μm in thickness. Two sub-spherical polar capsules equal in size, situated at the same level and measured 3.0 ± 0.2 (3.0-3.2) μm in length and 2.4 ± 0.3 (2.3-3.3) μm in width. The infection with C. scorpaeni n. sp. was prevalent throughout the year with a maximum prevalence of infection during spring and summer. Molecular analysis of the SSU rRNA gene confirmed the parasite as a new member of the genus Ceratomyxa and showed close relationship with the species of Ceratomyxa infecting the gallbladders of Sparidae from the Mediterranean Sea. This is the first report of Ceratomyxa species from the gallbladder of S. porcus in Tunisian coastal waters.

Enteromyxum leei (Myxosporea: Bivalvulida) as the cause of myxosporean emaciation disease of farmed olive flounders (Paralichthys olivaceus) and a turbot (Scophthalmus maximus) on Jeju Island, Korea.

A life-threatening emaciation disease of unknown cause(s) is affecting the farming of olive flounders (Paralichthys olivaceus) and turbots (Scophthalmus maximus) on Jeju Island, Korea. As this is one of the major industries in the region, it is of great concern to local farmers trying to develop successful and sustainable aquaculture. We examined 16 olive flounders and one turbot cultured at three farms located in the southern part of Jeju Island, which manifested moderate to severe emaciation such as thinning of the body with notable appearance of bony ridges of the skull on heads. Fresh mucosal scrapings of the intestinal mucosa contained many myxosporean vegetative stages at various developments but not fully grown spores. Histological examination of gastrointestinal and other visceral organs revealed striking changes in the intestinal mucosa such as detachment and loss of the epithelium due to intensive parasitism of the myxosporean vegetative stages, accompanied by considerable leukocyte infiltration in the lamina propria, and at the final stage villus atrophy with no epithelial lining. Specific polymerase chain reaction using a pair of primers targeting a fragment of the 18S ribosomal RNA gene (rDNA) of Enteromyxum leei, a known pathogen causing myxosporean emaciation disease in a variety of cultured fish in Mediterranean countries and Japan, amplified 433-bp products in almost all diseased fish samples, particularly the gastrointestinal tract. Nearly the whole length of the 18S rDNA, 1672-bp long excluding primer-aligning sequences, of the present Korean isolate was comparable to those of E. leei isolates from Japan and Europe, particularly those from the former region. Taking the heavy load of various developmental stages of E. leei in the gastrointestinal mucosa into account, we ascribe the emaciation disease of the fish examined in the present study to this well-known myxosporean species and not to another unknown pathogen(s).

Morphology, seasonality and phylogeny of Zschokkella trachini n. sp. (Myxozoa, Myxosporea) infecting the gallbladder of greater weever Trachinus draco (L.) from Tunisian waters.

We describe a new myxosporean species, Zschokkella trachini n. sp., infecting the gallbladder of greater weever Trachinus draco Linnaeus 1758 from Tunisia. This is the first record of Zschokkella species in T. draco. Plasmodia were polysporic producing six to eight mature spores; they were attached to the gallbladder epithelium or free floating in the bile. Mature spores were sub-ovoid in the frontal view, measured 15.2 ± 0.6 (14.4-16.0) μm in length and 9.8 ± 0.7 (9.0-10.8) μm in width. Two equal spherical polar capsules 4.0 ± 0.4 (3.6-4.5) μm in diameter, were located separately at the spore's extremities. The prevalence of infection ranged from 23.5 to 87.7%. Morphological data and molecular analysis of the small subunit rDNA gene identified this parasite as a new species of Zschokkella. Neighbour joining clustered the parasite in a sub-clade containing other Zschokkella species parasiting the gallbladder of marine fish hosts, located within the coelozoic clade of the major freshwater clade. This is the second Zschokkella species reported from Tunisia.

Intraspecific morphometric variation in myxosporeans.

Morphometric data from spores of ten myxosporean species were statistically analysed to explore myxosporean intraspecific variation in measurements when obtained from a sample from: (1) the same plasmodium, (2) different plasmodia from the same host and (3) different host individuals and localities. In some cases, significant differences in spore dimensions were found between samples from the same plasmodium, highlighting the difficulty of obtaining representative measurements of myxosporean spore. In addition, significant differences in spore dimensions were found when plasmodia from the same site of infection were compared, suggesting that measurements of spores should come from several different plasmodia of the sampling to increase the reliability of the morphology data. Moreover, significant differences in spore dimensions were observed for most spore dimensions when data were compared between localities. In all cases, there was clear overlap in ranges of dimensions even when means differed significantly. The present statistical analysis shows that intraspecific morphometric variation of myxosporean species commonly occurs, highlighting the importance of reporting ranges of measurements for a species, not just the mean dimensions, and taking into account all evidence when assigning or describing myxosporean species.

Prevalence, site and tissue preference of myxozoan parasites infecting gills of cultured fish in Punjab (India).

Native carp species cultured in Indian farms in Punjab (catla Catla catla, rohu Labeo rohita, mrigal Cirrhinus mrigala, exotic carps such as silver carp Hypophthalmichthys molitrix, grass carp Ctenopharyngodon idella, common carp Cyprinus carpio and a catfish Sperata seenghala) were examined for the presence of myxozoan parasites infecting gills. Firstly, the gills were examined under a zoom-stereomicroscope for the presence of plasmodia. The number of plasmodia per gill was counted to determine the index for the intensity of infection. Infected tissues were processed for histology, and 3-4 µm sections of infected gills were stained with haematoxylin & eosin and Luna's method. A total of 19 species of myxosporean were found infecting various cell types in the gills. Of these, 14 species belonged to the genus Myxobolus, 3 species to the genus Thelohanellus and 2 species to the genus Henneguya. Species belonging to the genus Myxobolus formed the interlamellar and intralamellar vascular (LV) type plasmodia, and species belonging to the genus Thelohanellus and Henneguya formed intrafilamental vascular (FV) type plasmodia. Mixed infections comprising 2, 3 or 4 different myxozoan species were noted in individual fish. The most common type of parasitism was polyparasitism due to 4 myxobolids co-occuring in fish with an infection rate of 23.16%. All species caused mild to severe haemorrhagic gill disease with little clinical symptomatology.

Morphological and molecular genetic characterization of two Kudoa spp., K. musculoliquefaciens, and K. pleurogrammi n. sp. (Myxosporea: Multivalvulida), causing myoliquefaction of commercial marine fish.

Genetic characterization of myxosporean species, including members of the genus Kudoa, has advanced dramatically throughout the last decade. This is in stark contrast to those species described further back in time. Kudoa musculoliquefaciens described from the jellied muscle of swordfish, Xiphias gladius, in the western Pacific Ocean off the Sanriku Coast, northern Japan, is one such species. In the present study, multiple pseudocysts (0.66-1.35mm average length and 0.06-0.10mm average width) containing K. musculoliquefaciens spores were collected from three host groups: muscle blocks of swordfish caught in the western Pacific Ocean off the Sanriku Coast, or the northern Indian Ocean, and Indo-Pacific sailfish, Istiophorus platypterus, in the western Pacific Ocean off Kochi, western Japan. Subspherical K. musculoliquefaciens spores, 8.0-10.3μm in width, 7.3-10.0μm in thickness, 6.4-7.9μm in sutural thickness, and 5.5-8.1μm in length, had four subspherical polar capsules, 2.8-4.0μm in length by 2.2-3.2μm in width. The kudoid spores found in the different host groups showed morphometric variations to some extent but had essentially identical nucleotide sequences of the ribosomal RNA gene (rDNA), closest to those of Kudoa hemiscylli or Kudoa carcharhini recorded from elasmobranchs in the Indo-Pacific Ocean. Another kudoid species, Kudoa pleurogrammi n. sp., was recorded from the jellied and normal muscles of Atka mackerel, Pleurogrammus monopterygius and Pleurogrammus azonus, fished in the northern Pacific Ocean or northern Sea of Japan. Subquadrate spores found in round-ended pseudocysts (1.15-3.85mm in length and 0.11-0.26mm in width) in myofibers were 8.2-9.1μm in width, 7.1-8.2μm in thickness, 5.4-7.7μm in sutural thickness, and 5.6-6.8μm in length, with four ovoid polar capsules, 2.7-2.9μm in length by 1.4-2.0μm in width. Kudoid spores from both jellied and normal muscles or different host fish species had identical 18S or 28S rDNA nucleotide sequences. Thus, molecular genetic characterization of kudoid species with the potential to induce post-mortem myoliquefaction will facilitate the reliable and specific identification of myxosporeans found in either jellied or normal muscles of important commercial fish.

Description of a myxozoan parasite Myxobolus sp.n PKB2014 from an edible fish, with emphasis on its molecular characterization.

In India, more than 104 species of Myxobolus have so far been reported infecting freshwater as well as marine fishes. The study focuses on the description of a new myxosporean species, Myxobolus sp.n PKB 2014 from the gill lamellae of an Indian major carp Labeo rohita. The species have been described on the basis of morphological characterization of the spores, tissue architecture and 18S rDNA sequence data. The plasmodia of Myxobolus sp.n PKB 2014 were round in shape measuring, 50 to 70 μm in diameter and spores were ellipsoidal in frontal view measures 14.7 ± 0.51 μm. The 18S rRNA nucleotide sequence with 806 bp of Myxobolus sp.n PKB 2014 (Accession number KJ652226) clustered phylogenitically with other Myxobolus spp. infecting cyprinid gills with 90-99% similarity. According to the phylogenetic study we concluded that M. wulli was the closest relative having 99% similarity with the species under description but the sequence was distinct in each species which additionally exhibited different morphological features. The infection rate was low to moderate. After through comparison it can be concluded that the species being described here is new to science which is designated as Myxobolus sp.n. PKB 2014.

The phylogenetic position of Myxoboluscarnaticus (Myxozoa, Myxosporea, Bivalvulida) infecting gill lamellae of Cirrhinus mrigala (Hamilton, 1822) based on 18S rRNA sequence analysis.

Myxozoans are an economically important group of microscopic parasites best known for the diseases they cause in commercially important fish hosts. The classification of myxosporeans is generally based on the morphology of their myxospores. Without molecular data, it is very difficult to identify new or existing species. DNA sequence information is therefore, a prerequisite to taxonomic and phylogenic studies of myxosporeans. In the present study, a myxozoan parasite, Myxobolus carnaticus, infecting the gill lamellae of mrigal carp, Cirrhinus mrigala, was characterized by the 18S rRNA gene sequence. The DNA sequence of M. carnaticus clustered phylogenetically with other gill infecting Myxobolus spp. of freshwater clades, forming a dichotomy with closely related M. pavlovskii (HM991164) that infects the gill lamellae epithelium of silver carp, Hypophthalmichthys molitrix with 95% similarity. Evolutionary pair-wise distances among M. carnaticus and other species of myxosporeans indicated high genetic diversity among myxosporeans. The present study demonstrated that tissue tropism, host specificity and habitat play important roles in phylogenetic relationships among myxozoan species.

Ultrastructural and Phylogenetic Description of Kudoa orbicularis n. sp. (Myxosporea: Multivalvulida): A Parasite Infecting the Muscle of the Fish Chaetobranchopsis orbicularis (Teleostei: Cichlidae) in the Amazon Region.

A new myxosporean species is described from the muscle of the Amazonian freshwater fish Chaetobranchopsis orbicularis (Teleostei, Cichlidae), with basis on morphometric, ultrastructural and molecular data. Numerous myxospores were observed within pseudocysts located on the hosts' dorsal and ventral muscles, near the neural spines and neural canal (spinal cord). Mature myxospores quadrangular with rounded ends in apical view, measuring 4.3 (3.6-5.0)μm in length and 5.1 (4.2-5.8)μm in width. The myxospores wall is formed by four symmetric valves. Within, four pyriform polar capsules, 2.1 (1.7-2.6)μm long and 1.3 (0.9-1.7)μm wide, located two by two in opposite sides of the myxospores longitudinal axis, each containing a polar filament forming 2-3 coils. Molecular analysis of the SSU rRNA gene by maximum likelihood, neighbor-joining and maximum parsimony confirms the parasite as a new member of the genus Kudoa, herein named Kudoa orbicularis n. sp., the second species of its genus reported from the South American freshwater fauna, and the fourth species worldwide known to occur in the freshwater environment. Furthermore, its sequence of the SSU rRNA gene constitutes the first entry of a freshwater Kudoa species in GenBank.

Twelve myxosporean species of the family Myxobolidae infecting freshwater fishes of the River Nile, Egypt, with the description of four novel species.

Myxosporidian parasites infecting fish are very dangerous parasites causing severe damage to a large number of economically important fishes especially in aquaculture. A survey of myxosporean parasites infecting four species of fishes from the River Nile in Egypt is conducted. One hundred and ninety-five out of 316 fish specimens with a percentage of 61.7% were found to be naturally infected with these parasites. Light microscopic examination of different tissues revealed the presence of 12 myxosporean species belonging to the family Myxobolidae. Four of the identified species are novel and the other eight species are redescribed. Myxidium sp.nov. a coelozoic species inhabiting the gallbladder of Labeo niloticus with its mature spores float free in bile was detected. These spores possess a fusiform, straight, or slightly crescentic shape with less pointed ends and two equal polar capsules. Three novel histozoic Myxobolus species infecting Oreochromis niloticus were identified. Myxobolus sp(1).nov. is a species inhabiting kidney tissue with ovoid spores exhibiting a small intercapsular appendix. Myxobolus sp(2).nov. and Myxobolus sp(3).nov. recovered from kidney and intestinal tissues. Spores of Myxobolus sp(2).nov. are elliptical in shape with an anterior end wider than posterior one. Their two polar capsules are ovoid to pyriform occupied nearly the first third of the spore body. Spores of Myxobolus sp(3).nov. are broader than long with nearly rounded or ovoid two polar capsules. Eight species of the recovered myxosporean parasites are redescribed, Myxobolus niloticus Fahmy et al., 1971 from pectoral, dorsal, and tail fins of L. niloticus, Henneguya suprabranchiae Landsberg, 1987, and Henneguya branchialis Ashmawy et al., 1989 are recovered from the gills and suprabranchial organ of the catfish Clarias gariepinus, respectively, Myxobolus naffari Abdel-Ghaffar et al., 1998 and Myxobolus imami Ali et al., 2002 are found in the kidney of Barbus bynni and L. niloticus, Myxobolus caudatus Ali et al. & Parasitol Res (2002) from Tail fin of B. bynni, Myxobolus fomenai Abdel-Ghaffar et al., 2008 from kidney and intestinal tissues of O. niloticus, Thelohanellus niloticus Abdel-Ghaffar et al., 2012 are observed in the gills of L. niloticus.

Evolutionary origin of Ceratonova shasta and phylogeny of the marine myxosporean lineage

In order to clarify the phylogenetic relationships among the main marine myxosporean clades including newly established Ceratonova clade and scrutinizing their evolutionary origins, we performed large-scale phylogenetic analysis of all myxosporean species from the marine myxosporean lineage based on three gene analyses and statistical topology tests. Furthermore, we obtained new molecular data for Ceratonova shasta, C. gasterostea, eight Ceratomyxa species and one Myxodavisia species. We described five new species: Ceratomyxa ayami n. sp., C. leatherjacketi n. sp., C. synaphobranchi n. sp., C. verudaensis n. sp. and Myxodavisia bulani n. sp.; two of these formed a new, basal Ceratomyxa subclade.We identified that the Ceratomyxa clade is basal to all other marine myxosporean lineages, and Kudoa with Enteromyxum are the most recently branching clades. Topologies were least stable at the nodes connecting the marine urinary clade, the marine gall bladder clade and the Ceratonova clade. Bayesian inference analysis of SSU rDNA and the statistical tree topology tests suggested that Ceratonova is closely related to the Enteromyxum and Kudoa clades, which represent a large group of histozoic species. A close relationship between Ceratomyxa and Ceratonova was not supported, despite their similar myxospore morphologies. Overall, the site of sporulation in the vertebrate host is a more accurate predictor of phylogenetic relationships than the morphology of the myxospore.

Ortholinea saudii sp. nov. (Myxosporea: Ortholineidae) in the kidney of the marine fish Siganus rivulatus (Teleostei) from the Red Sea, Saudi Arabia.

Myxozoans, a diverse group of microscopic obligate endoparasites, can cause diseases in a number of economically important fish, including the marbled spinefoot Siganus rivulatus. To date, only 1 myxozoan, Zschokkella helmii, has been reported to infect S. rivulatus. Here we describe another myxozoan detected in S. rivulatus. Investigations of 40 marbled spinefoot fish caught from the Red Sea coast, Jeddah, Saudi Arabia, revealed clusters of parasitic spores in the kidney. Light microscope examination of the native spores revealed sub-spherical, mature spores with smooth shell valves. The 2 polar capsules were equal in size, and the polar filament was perpendicular to the longitudinal axis of the polar capsules. Histopathological examinations of the infected kidneys demonstrated the presence of both spores and developmental stages in the lumen of the renal tubules without any pathological effect. Electron microscopy investigations showed maturing spores composed of 2 valvogenic cells, each with a prominent nucleus. The valvogenic cells enclosed 2 polar capsules containing 3 filament coils as well as a binucleated sporoplasm cell filling the space between and beneath the 2 polar capsules. BLAST search analysis of the amplified sequence from the detected parasite indicated a high percent of identity to the 18S rDNA genes of different myxosporean species. Phylogenetic analysis placed the detected parasite within a clade of Ortholinea sp. (AL-2006). Based on the results of the light and electron microscopy, histopathological, and molecular investigations, the detected parasite was identified as a myxosporean parasite belonging to the genus Ortholinea and designated as O. saudii sp. nov.