Myxozoans are microscopical parasites widely distributed in fish, with over 2,600 described species, but their actual diversity is still underestimated. Among salmonids, more than 70 myxozoan species have been identified. This study focuses on species of Chloromyxum Mingazzini, 1890 that infect salmonid kidneys, particularly C. majori Yasutake et Wood, 1957 and C. schurovi Shulman et Ieshko, 2003. Despite their similar spore morphology, they exhibit distinct host preferences, tissue affinities and geographical distributions. Chloromyxum schurovi predominantly infects the renal tubules of Salmo salar Linnaues and S. trutta Linnaeus in Europe, while C. majori targets the glomeruli of Oncorhynchus mykiss (Walbaum) and O. tshawytscha (Walbaum) in North America. The sequence data for C. majori and C. schurovi have been either missing or questionable. In our study, we examined the kidneys of two salmonid species for chloromyxid infections, using both morphological and molecular data to characterise Chloromyxum species in salmonids. The sequence of C. schurovi obtained in our study did not match the previously published parasite data. Instead, it clustered as an independent lineage sister to the Paramyxidium Freeman et Kristmundsson, 2018 clade gathering the species from various fish organs, including the urinary tract. Our findings clarified the taxonomic origin of the previous C. schurovi sequence as Myxidium giardi Cépède, 1906, highlighting the risks associated with the presence of myxozoan blood stages in the bloodstream of their fish host and the challenges of non-specific PCR amplification. We redescribe C. schurovi, thus contributing to a better understanding of the diversity and phylogeny of kidney-infecting species of Chloromyxum.

• Klíčová slova
• Myxozoan diversity, PCR screening, Salmo trutta, phylogeny,
• MeSH
• fylogeneze * MeSH
• ledviny parazitologie   MeSH
• Myxozoa * klasifikace   genetika   anatomie a histologie   izolace a purifikace   MeSH
• nemoci ryb * parazitologie   MeSH
• parazitární nemoci u zvířat * parazitologie   epidemiologie   MeSH
• pstruh * parazitologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Myxidium rhodei Léger, 1905 (Cnidaria: Myxozoa) is a kidney-infecting myxosporean that was originally described from the European bitterling Rhodeus amarus. Subsequently, it has been documented based on spore morphology in more than 40 other cypriniform species, with the roach Rutilus rutilus being the most commonly reported host. This study introduces the first comprehensive data assessment of M. rhodei, conducted through morphological, ecological and molecular methods. The morphological and phylogenetic analyses of SSU rDNA sequences of Myxidium isolates obtained from European bitterling and roach did not support parasite conspecificity from these fish. In fact, the roach-infecting isolates represent three distinct parasite species. The first two, M. rutili n. sp. and M. rutilusi n. sp., are closely related cryptic species clustering with other myxosporeans in the freshwater urinary clade, sharing the same tissue tropism. The third one, M. batuevae n. sp., previously assigned to M. cf. rhodei, clustered in the hepatic biliary clade sister to bitterling-infecting M. rhodei. Our examination of diverse cypriniform fishes, coupled with molecular and morphological analyses, allowed us to untangle the cryptic species nature of M. rhodei and discover the existence of novel species. This underscores the largely undiscovered range of myxozoan diversity and highlights the need to incorporate sequence data in diagnosing novel species.

TITLE: Résoudre le casse-tête de Myxidium rhodei (Myxozoa) : aperçu de sa phylogénie et de sa spécificité d’hôte chez les Cypriniformes. ABSTRACT: Myxidium rhodei Léger, 1905 (Cnidaria : Myxozoa) est un Myxosporea infectant les reins qui a été décrit à l’origine chez la bouvière, Rhodeus amarus. Par la suite, il a été documenté, sur la base de la morphologie des spores, chez plus de 40 autres espèces de cypriniformes, le gardon Rutilus rutilus étant l’hôte le plus fréquemment signalé. Cette étude présente la première évaluation complète des données sur M. rhodei, réalisée par des méthodes morphologiques, écologiques et moléculaires. Les analyse morphologiques et phylogénétiques des séquences d’ADNr SSU des isolats de Myxidium obtenus à partir de bouvières et de gardons européens n’ont pas confirmé la conspécificité du parasite de ces poissons. En fait, les isolats infectant les gardons représentent trois espèces distinctes de parasites. Les deux premières, M. rutili n. sp. et M. rutilusi n. sp., sont des espèces cryptiques étroitement apparentées, regroupées avec d’autres Myxosporea du clade urinaire d’eau douce, partageant le même tropisme tissulaire. La troisième, M. batuevae n. sp., précédemment attribuée à M. cf. rhodei, appartient au clade biliaire hépatique, groupe-frère de M. rhodei infectant la bouvière. Notre examen de divers poissons cypriniformes, couplé à des analyses moléculaires et morphologiques, nous a permis de démêler la nature cryptique des espèces de M. rhodei et de découvrir l’existence de nouvelles espèces. Cela souligne la diversité largement méconnue des Myxozoaires et souligne la nécessité d’incorporer des données de séquence dans le diagnostic de nouvelles espèces.

• Klíčová slova
• Cryptic species, Host specificity, Kidney-infecting Myxidium spp., Myxozoa, PCR screening, Phylogeny,
• MeSH
• Cyprinidae parazitologie   MeSH
• fylogeneze * MeSH
• hostitelská specificita * MeSH
• ledviny parazitologie   MeSH
• máloostní * parazitologie   MeSH
• Myxozoa * klasifikace   genetika   izolace a purifikace   MeSH
• nemoci ryb * parazitologie   MeSH
• parazitární nemoci u zvířat * parazitologie   MeSH
• ribozomální DNA MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• ribozomální DNA MeSH

Myxozoans are a unique group of microscopic parasites that infect mainly fishes. These extremely reduced cnidarians are highly diverse and globally distributed in freshwater and marine habitats. Myxozoan diversity dimension is unknown in Mexico, a territory of an extraordinary biological diversity. This study aimed to explore, for the first time, myxozoan parasite diversity from fishes of the Neotropical region of Mexico. We performed a large morphological and molecular screening using host tissues of 22 ornamental and food fish species captured from different localities of Veracruz, Oaxaca and Chiapas. Myxozoan infections were detected in 90% of the fish species, 65% of them had 1 or 2 and 35% had 3 and up to 8 myxozoan species. Forty-one putative new species were identified using SSU rDNA phylogenetic analyses, belonging to two main lineages: polychaete-infecting (5 species) and oligochaete-infecting (36 species) myxozoans; from those we describe 4 new species: Myxidium zapotecus sp. n., Zschokkella guelaguetza sp. n., Ellipsomyxa papantla sp. n. and Myxobolus zoqueus sp. n. Myxozoan detection increased up to 6 × using molecular screening, which represents 3.7 × more species detected than by microscopy. This study demonstrated that Neotropical fishes from Mexico are hosts of a multitude of myxozoans, representing a source of emerging diseases with large implications for economic and conservation reasons.

• MeSH
• Cnidaria * genetika   MeSH
• fylogeneze MeSH
• Myxobolus * genetika   MeSH
• Myxozoa * genetika   MeSH
• nemoci ryb * epidemiologie   parazitologie   MeSH
• parazitární nemoci u zvířat * epidemiologie   parazitologie   MeSH
• ribozomální DNA genetika   MeSH
• ryby genetika   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Mexiko MeSH
• Názvy látek
• ribozomální DNA MeSH

It is assumed that complex life cycles in cnidarian parasites belonging to the Myxozoa result from incorporation of vertebrates into simple life cycles exploiting aquatic invertebrates. However, nothing is known about the driving forces and implementation of this event, though it fostered massive diversification. We performed a comprehensive search for myxozoans in evolutionary ancient fishes (Chondrichthyes), and more than doubled existing 18S rDNA sequence data, discovering seven independent phylogenetic lineages. We performed cophylogenetic and character mapping methods in the largest monophyletic dataset and demonstrate that host and parasite phylogenies are strongly correlated, and that tectonic changes may explain phylogeographic clustering in recent skates and softnose skates, in the Atlantic. The most basal lineages of myxozoans inhabit the bile of chondrichthyans, an immunologically privileged site and protective niche, easily accessible from the gut via the bile duct. We hypothesize that feed-integration is a likely mechanism of host acquisition, an idea supported by feeding habits of chimaeras and ancient sharks and by multiple entries of different parasite lineages from invertebrates into the new host group. We provide exciting first insights into the early evolutionary history of ancient metazoan parasites in a host group that embodies more evolutionary distinctiveness than most other vertebrates.

• Klíčová slova
• Chondrichthyes, cnidaria, co-diversification, co-phylogeny, feed-integration, migration, myxozoa, phylogeography,
• Publikační typ
• časopisecké články MeSH

The genus Chloromyxum (Myxozoa: Myxosporea: Bivalvulida) is defined as having ridged or smooth bivalvular myxospores containing four polar capsules, with/without caudal filaments. Currently containing more than 140 nominal species, this genus is reasonably speciose with myxospores of unique but heterogeneous morphology. Recent phylogenetic studies have demonstrated its polyphyletic nature. During our myxosporean survey of freshwater fish, a new coelozoic myxosporean species, Chloromyxum trilineatum n. sp., was detected in the gall bladder of the pale chub, Zacco platypus (Cypriniformes: Cyprinidae), which originated from central Japan. Spores were subspherical, measuring 8.5-9.1 (8.8) μm in length, 7.6-8.2 (8.0) μm in width, and 6.8-7.8 (7.4) μm in thickness (n = 20). The valvular surface was smooth and three or four distinct ridges ran parallel to the suture line. Four almost equal polar capsules, 2.9-3.8 (3.3) μm in length and 1.6-2.4 (2.0) μm in width, assembled at the apical part of the spores. The partial nucleotide sequence of the 18S ribosomal RNA gene, 2014 bp in length, was closest to that of morphologically distinct Chloromyxum ellipticum, infecting the gall bladder of grass carp (Ctenopharyngodon idella) in China with 96.99% (1673/1725) identity and three insertion/deletion (indel) sites, followed by Chloromyxum legeri, infecting the gall bladder of common carp (Cyprinus carpio) in the Czech Republic with 89.97% (1803/2004) identity and 14 indel sites. Other myxosporean species, including Chloromyxum spp. from the gall bladder or urinary system of freshwater and marine fish, were phylogenetically distant from the present species.

• Klíčová slova
• 18S rDNA, Chloromyxum, Morphology, Myxozoa, Phylogeny, SEM, Zacco platypus,
• MeSH
• Cyprinidae parazitologie   MeSH
• fylogeneze MeSH
• Myxozoa klasifikace   genetika   MeSH
• nemoci ryb parazitologie   MeSH
• parazitární nemoci u zvířat parazitologie   MeSH
• ribozomální DNA genetika   MeSH
• RNA ribozomální 18S genetika   MeSH
• sekvence nukleotidů MeSH
• žlučník parazitologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Česká republika MeSH
• Čína MeSH
• Japonsko MeSH
• Názvy látek
• ribozomální DNA MeSH
• RNA ribozomální 18S MeSH

The Patagonian seabass Acanthistius patachonicus (Jenyns, 1840) (Serranidae) is a marine fish valued for commercial and sport fisheries from Argentina. We report a new myxosporean (Cnidaria: Myxozoa) infecting the urinary system of the Patagonian seabass from San Antonio Bay, San Matías Gulf, on the Atlantic Ocean. The mature myxospores were subspherical, 8.2-11.0 μm × 7.9-11.0 μm and 7.7-9.0 μm in thickness; two subspherical polar capsules, 2.4-3.8 μm × 2.3-3.6 μm, with 3 to 4 turns of the polar tubule; openings on different valves in almost opposite directions. Ornamented shell valves exhibited 17-20 concentrically organized surface ridges. SSU rDNA phylogenetics analyses placed the new species in the freshwater urinary tract clade, clustering in a clade formed by Myxobilatus gasterostei (Parisi, 1912), Acauda hoffmani Whipps, 2011, and other Ortholinea spp. Based on spore morphology, site of infection, and molecular data, we described this myxozoan as Ortholinea concentrica n. sp.

• Klíčová slova
• Marine fish, Myxozoa, Phylogeny, SSU rDNA, South America, Taxonomy, Urinary system,
• MeSH
• fylogeneze MeSH
• močové ústrojí parazitologie   MeSH
• Myxozoa * klasifikace   genetika   izolace a purifikace   MeSH
• nemoci ryb parazitologie   MeSH
• parazitární nemoci u zvířat parazitologie   MeSH
• Percoidea parazitologie   MeSH
• ribozomální DNA genetika   MeSH
• spory klasifikace   MeSH
• zvířata MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Argentina MeSH
• Atlantský oceán MeSH
• Názvy látek
• ribozomální DNA MeSH

During a survey on the myxosporean fauna of Rajiformes from the Atlantic coast of Argentina, in waters off Buenos Aires Province (34°-42°S; 53°-62°W), the gall bladders of 217 specimens belonging to seven species of skates, representatives of two families, were examined. As a result, three species of Chloromyxum Mingazzini, 1890, namely C. atlantoraji n. sp., C. zearaji n. sp. and C. riorajum Azevedo, Casal, Garcia, Matos, Teles-Grilo and Matos, 2009 were found infecting three endemic host species, the spotback skate Atlantoraja castelnaui (Arhynchobatidae), the yellownose skate Zearaja chilensis (Rajidae) and the Rio skate Rioraja agassizii (Arhynchobatidae), respectively. These species were described based on myxospore morphology and morphometry characterization, as well as by providing their small subunit ribosomal DNA (SSU rDNA) sequences. The SSU rDNA-based phylogenetic analyses showed that these three species constituted a well-established monophyletic subclade within the marine Chloromyxum clade, while branches subtending the other Chloromyxum species were poorly resolved or unresolved, independently of the host taxonomic identities (Carchariniformes, Myliobatiformes, Orectolobiformes, Pristiophoriformes, Rajiformes, Squaliformes and Torpediniformes) and/or host geographic distribution (Atlantic coast of Portugal, Atlantic coast of the USA, Australian waters or Mediterranean Sea). The possible causes of these discrepancies are discussed, providing new insights into the phylogeny of the marine Chloromyxum clade.

Lors d’une étude de la faune des Myxozoaires des Rajiformes de la côte atlantique argentine, dans les eaux situées au large de la province de Buenos Aires (34°–42°S; 53°–62°O), les vésicules biliaires de 217 spécimens appartenant à sept espèces, représentants deux familles, ont été examinés. En conséquence, trois espèces de Chloromyxum Mingazzini, 1890, à savoir C. atlantoraji n. sp., C. zearaji n. sp. et C. riorajum Azevedo, Casal, Garcia, Matos, Teles-Grilo et Matos, 2009 ont été trouvées, infectant trois espèces hôtes endémiques, Atlantoraja castelnaui (Arhynchobatidae), Zearaja chilensis (Rajidae) et Rioraja agassizii (Arhynchobatidae), respectivement. Ces espèces sont décrites sur la base de la morphologie et de la morphométrie des myxospores, ainsi qu’en fournissant leurs petites séquences d’ADN ribosomal (SSU ADNr). Les analyses phylogénétiques basées sur l’ADNr SSU ont montré que ces trois espèces constituaient un sous-clade monophylétique bien établi dans le clade des Chloromyxum marins, tandis que les branches sous-jacentes aux autres espèces de Chloromyxum étaient mal ou non résolues, indépendamment des identités taxonomiques hôtes (Carchariniformes, Myliobatiformes, Orectolobiformes, Pristiophoriformes, Rajiformes, Squaliformes et Torpediniformes) et/ou de la répartition géographique de l’hôte (côte atlantique du Portugal, côte atlantique des États-Unis, eaux australiennes ou mer Méditerranée). Les causes possibles de ces divergences sont discutées, fournissant de nouvelles informations sur la phylogénie du clade des Chloromyxum marins.

• MeSH
• druhová specificita MeSH
• fylogeneze * MeSH
• mikroskopie elektronová rastrovací MeSH
• Myxozoa klasifikace   genetika   izolace a purifikace   MeSH
• nemoci ryb epidemiologie   parazitologie   MeSH
• oceány a moře MeSH
• parazitární nemoci u zvířat epidemiologie   parazitologie   MeSH
• rejnokovití parazitologie   MeSH
• ribozomální DNA genetika   MeSH
• sekvence nukleotidů MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Argentina epidemiologie   MeSH
• oceány a moře MeSH
• Názvy látek
• ribozomální DNA MeSH

BACKGROUND: Myxozoa are extremely diverse microscopic parasites belonging to the Cnidaria. Their life-cycles alternate between vertebrate and invertebrate hosts, predominantly in aquatic habitats. Members of the phylogenetically well-defined Sphaerospora (sensu stricto) clade predominantly infect the urinary system of marine and freshwater fishes and amphibians. Sphaerosporids are extraordinary due to their extremely long and unique insertions in the variable regions of their 18S and 28S rDNA genes and due to the formation of motile proliferative stages in the hosts' blood. To date, DNA sequences of only 19 species have been obtained and information on the patterns responsible for their phylogenetic clustering is limited. METHODS: We screened 549 fish kidney samples from fish of various geographical locations, mainly in central Europe, to investigate sphaerosporid biodiversity microscopically and by 18S rDNA sequences. We performed multiple phylogenetic analyses to explore phylogenetic relationships and evolutionary trends within the Sphaerospora (s.s.) clade, by matching host and habitat features to the resultant 18S rDNA trees. The apparent co-clustering of species from related fish hosts inspired us to further investigate host-parasite co-diversification, using tree-based (CoRE-PA) and distance-based (ParaFit) methods. RESULTS: Our study considerably increased the number of 18S rDNA sequence data for Sphaerospora (s.s.) by sequencing 17 new taxa. Eight new species are described and one species (Sphaerospora diminuta Li & Desser, 1985) is redescribed, accompanied by sufficient morphological data. Phylogenetic analyses showed that sphaerosporids cluster according to their vertebrate host order and habitat, but not according to geography. Cophylogenetic analyses revealed a significant congruence between the phylogenetic trees of sphaerosporids and of their vertebrate hosts and identified Cypriniformes as a host group of multiple parasite lineages and with high parasite diversity. CONCLUSIONS: This study significantly contributed to our knowledge of the biodiversity and evolutionary history of the members of the Sphaerospora (s.s.) clade. The presence of two separate phylogenetic lineages likely indicates independent historical host entries, and the remarkable overlap of the larger clade with vertebrate phylogeny suggests important coevolutionary adaptations. Hyperdiversification of sphaerosporids in cypriniform hosts, which have undergone considerable radiations themselves, points to host-driven diversification.

• Klíčová slova
• Host-parasite codiversification, Myxozoa, Phylogeny, Sphaerospora sensu stricto, Taxonomy, Teleost,
• MeSH
• biodiverzita * MeSH
• biologická evoluce MeSH
• Cnidaria MeSH
• fylogeneze * MeSH
• Myxozoa klasifikace   genetika   izolace a purifikace   fyziologie   MeSH
• nemoci ryb parazitologie   MeSH
• parazitární nemoci u zvířat genetika   parazitologie   MeSH
• ribozomální DNA genetika   MeSH
• ryby klasifikace   genetika   parazitologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• ribozomální DNA MeSH

INTRODUCTION: Intertidal rock pools where fish and invertebrates are in constant close contact due to limited space and water level fluctuations represent ideal conditions to promote life cycles in parasites using these two alternate hosts and to study speciation processes that could contribute to understanding the roles of parasitic species in such ecosystems. MATERIAL AND METHODS: Gall bladder and liver samples from five clinid fish species (Blenniiformes: Clinidae) were morphologically and molecularly examined to determine the diversity, prevalence, distribution and host specificity of Ceratomyxa parasites (Cnidaria: Myxozoa) in intertidal habitats along the coast of South Africa. Phylogenetic relationships of clinid ceratomyxids based on the SSU rDNA, LSU rDNA and ITS regions were assessed additionally to the investigation of population genetic structure of Ceratomyxa cottoidii and subsequent comparison with the data known from type fish host Clinus cottoides. RESULTS AND DISCUSSION: Seven Ceratomyxa species including previously described Ceratomyxa dehoopi and C. cottoidii were recognized in clinids. They represent a diverse group of rapidly evolving, closely related species with a remarkably high prevalence in their hosts, little host specificity and frequent concurrent infections, most probably as a result of parasite radiation after multiple speciation events triggered by limited host dispersal within restricted spaces. C. cottoidii represents the most common clinid parasite with a population structure characterized by young expanding populations in the south west and south east coast and by older populations in equilibrium on the west coast of its distribution. Parasite and fish host population structures show overlapping patterns and are very likely affected by similar oceanographic barriers possibly due to reduced host dispersal enhancing parasite community differentiation. While fish host specificity had little impact on parasite population structure, the habitat preference of the alternate invertebrate host as well as tidal water exchange may be additional crucial variables affecting the dispersal and associated population structure of C. cottoidii.

• MeSH
• fylogeneze MeSH
• interakce hostitele a parazita genetika   fyziologie   MeSH
• Myxozoa klasifikace   genetika   MeSH
• nemoci ryb parazitologie   MeSH
• parazitární nemoci u zvířat parazitologie   MeSH
• paraziti klasifikace   genetika   MeSH
• populační genetika metody   MeSH
• ribozomální DNA genetika   MeSH
• ryby parazitologie   MeSH
• stadia vývoje genetika   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Jihoafrická republika MeSH
• Názvy látek
• ribozomální DNA MeSH

Myxosporean infections can cause severe damage to commercially grown tilapia. Here, we report a novel myxosporean that was found in gills of Oreochromis aureus male × Oreochromis niloticus female, which is an important aquaculture tilapia hybrid in Israel. Three-month-old fish were found to have cysts located in gill muscle tissue, which were filled with both immature and mature spores. Affected fish displayed higher mortality rate. Spore dimensions (10.8 ± 0.7 μm length × 6.8 ± 0.6 μm width) and molecular characterization using 18S ribosomal DNA revealed that the unknown parasite belongs in the Myxobolus clade. Based on the infection site, spore morphology and molecular characterization, we describe this parasite as Myxobolus bejeranoi n. sp. (MF401455). Phylogenetic analysis showed that the new species is most closely related to two Myxobolus spp. from O. niloticus in Egypt and Ghana.

• Klíčová slova
• Israel aquaculture, Myxobolus, Myxosporea, Oreochromis hybrid, Pathogenic parasite, Tilapia,
• MeSH
• fylogeneze MeSH
• Myxobolus klasifikace   genetika   izolace a purifikace   MeSH
• nemoci ryb parazitologie   MeSH
• parazitární nemoci u zvířat parazitologie   MeSH
• ribozomální DNA MeSH
• RNA ribozomální 18S genetika   MeSH
• spory fyziologie   MeSH
• svaly parazitologie   MeSH
• Tilapia parazitologie   MeSH
• žábry parazitologie   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Izrael MeSH
• Názvy látek
• ribozomální DNA MeSH
• RNA ribozomální 18S MeSH