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In this study, a Henneguya myxosporean species is described to infect an ecological, biological, and evolutionary important fish from Amazon biome. The myxosporean was found in the skin of only one specimen of marbled swamp eel, Synbranchus marmoratus caught in a small stream from Peruvian Amazon floodplain. Mature myxospores have ovoid shape from the valvular view, measuring 32.2 ± 0.6 μm (31.6–32.8) in total length, 21.5 ± 0.3 μm (21.2–21.8) in spore body length, 11.7 ± 0.5 μm (11.2–12.2) in width and 10.6 ± 0.9 μm (9.7–11.5) in thickness. Non-bifurcate caudal appendage, measuring 10.7 ± 0.4 μm (10.3–11.1) in length. Two polar capsules elongated aubergine in shape, equal in size and measuring 4.9 ± 0.2 μm (4.7–5.1) in length and 3.1 ± 0.5 μm (2.6–3.6) in width. Polar tubules coiled in 7–8 turns. This is the first report of a Henneguya species parasitizing a fish of the order Synbranchiformes from Amazon basin and the first to describe this parasite infecting a potamodromous fish from South America.

A synopsis of 43 nominal species from five genera of tailed Myxobolidae infecting Indian freshwater and marine fishes is presented. The main characteristic of this group is the presence of at least one tail-like caudal process. For each species, relevant morphological and morphometric data are provided, such as the host(s), site(s) of infection within the host and sampling state. A key for the identification of 13 genera of tailed Myxobolidae is also included.

Key to tailed genera of Myxobolidae 1a. Spores ovoid or pyriform, with two polar capsules and a single tail-like caudal process................................. 2 1b. Spores with two or more tail-like caudal processes or bifurcated tail; composed of same materials as shell valve......3 2a. Single tail-like caudal process; caudal process symmetrically located at the posterior end........................................................................................ Unicauda Davis, 1944 2b. Single tail-like caudal process, which may be forked at the very end, originating posterolaterally and asymmetrically.................. Laterocaudata Chen et Hsieh, 1984 3a. Spores tear-shaped shaped, with a single polar capsule, caudal process bifurcated..... Phlogospora Qadri, 1962 3b. Spores with two polar capsules and 2 caudal processes... 4 3c. Spores with two polar capsules and 4 caudal processes... 5 4a. Spores with two caudal processes.......................................................................... Henneguya Thélohan, 1892 4b. Spores with two caudal processes, asymmetric...................... Hennegoides Lom, Tonguthai et Dyková, 1991 4c. Spores with two caudal processes, extending in opposite directions............... Dicauda Hoffman et Walker, 1978 5a. Spores ellipsoidal with two caudal processes at each end of the spore; polar capsules situated asymmetrically............................................. Neohenneguya Tripathi, 1953 5b. Spores with four posterolateral caudal processes, two from each shell valve........................................................................... Tetrauronema Wu, Wang et Jiang, 1988 5c. Spores rhomboidal with four caudal processes pointing in the opposite direction, connected by transverse filaments............................ Trigonosporus Hoshina, 1952

Thelohanellus nikolskii, Achmerov, 1955 is a well-known myxozoan parasite of the common carp (Cyprinus carpio L.). Infection regularly manifests in numerous macroscopic cysts on the fins of two to three month-old pond-cultured carp fingerlings in July and August. However, a Thelohanellus infection is also common on the scales of two to three year-old common carp in ponds and natural waters in May and June. Based on myxospore morphology and tissue specificity, infection at both sites seems to be caused by the same species, namely T. nikolskii. This presumption was tested with molecular biological methods: SSU rDNA sequences of myxospores from fins of fingerlings and scales of older common carp were analysed and compared with each other and with related species available in GenBank. Sequence data revealed that the spores from the fins and scales represent the same species, T. nikolskii. Our study revealed a dichotomy in both infection site and time in T. nikolskii-infections: the fins of young carp are infected in Summer and Autumn, whereas the scales of older carp are infected in Spring. Myxosporean development of the species is well studied, little is known, however about the actinosporean stage of T. nikolskii. A previous experimental study suggests that aurantiactinomyxon actinospores of this species develop in Tubifex tubifex, Muller, 1774. The description included spore morphology but no genetic sequence data (Szekely et al., 1998). We examined >9000 oligochaetes from Lake Balaton and Kis-Balaton Water Reservoire searching for the intraoligochaete developmental stage of myxozoans. Five oligochaete species were examined, Isochaetides michaelseni Lastochin, 1936, Branchiura sowerbyi Beddard, 1892, Nais sp., Muller, 1774, Dero sp. Muller, 1774 and Aelosoma sp. Ehrenberg, 1828. Morphometrics and SSU rDNA sequences were obtained for the released actinospores. Among them, from a single Nais sp., the sequence of an aurantiactinomyxon isolate corresponded to the myxospore sequences of T. nikolskii.

The present paper describes a novel species of Myxobolus parasitizing the gill filaments of the largescale mullet, Planiliza macrolepis from Cochin backwaters, Kerala, India. The parasite develops in the gill filaments; plasmodia elongated, milky white, measured 1.37 – 2.18 (1.78 ± 0.35) mm x 0.07-0.12 (0.10 ± 0.02) mm in size. Mature myxospores ovoid in valvular view, biconvex in sutural view with smooth shell valves and measured 6.24 - 7.02 (6.63 ± 0.23) × 5.01 - 6.18 (5.68 ± 0.25) μm in size. Polar capsules equal, oval with pointed anterior ends, 3.07 – 3.58 (3.33 ± 0.12) × 1.68 – 2.42 (2.09 ± 0.18) μm in size. Polar filaments with 4 coils, measured 29.61 ± 4.75 μm in length when extruded. Sporoplasm binucleate with a rudimentary nucleus and a vacuole. A comparison with related Myxobolus species revealed significant morphological & morphometric differences. In BLASTN and genetic distance analysis, the present parasite showed high divergence with other myxosporean sequences, indicating its molecular uniqueness. In Maximum Likelihood and Bayesian Interference analysis, the present species stands out with M. ramadus as sister branch within the Myxobolus clade. In infected gill filaments, the plasmodia caused swelling/deformation, compression of lamellae and reduction in respiratory surface area. Three of 222 P. macrolepis screened were infected, indicating a prevalence of 1.3%. Considering the morphological, morphometric, molecular and phylogenetic differences with the previously described species of myxosporeans, along with the dissimilarities in host and geographical locations, the present parasite is treated as a new species and the name Myxobolus cochinensis n. sp. is proposed.

Myxobolus cerebralis (Hofer, 1903), the etiological agent of salmonid whirling disease, reportedly matures in only the oligochaete ‘Tubifex tubifex’. The concept of ‘T. tubifex’ is problematic because it is renowned as a species complex (or having ‘strains’), and many sequences ascribed to this taxon in GenBank are misidentified or indicate several cryptic species. These facts cast doubt on the long-held notion that M. cerebralis is strictly host-specific to the single definitive host, T. tubifex. Herein, as part of an ongoing regional whirling disease monitoring project, oligochaetes (452 specimens) were collected from 31 riverine sites in western North Carolina (August through September 2015) and screened for infection by M. cerebralis. The species-specific nested PCR for M. cerebralis was positive for 8 oligochaete specimens from the French Broad River Basin (Mill Creek and Watauga River) and New River Basin (Big Horse Creek). We individually barcoded these M. cerebralis-positive oligochaete specimens using cytochrome oxidase 1 (CO1) primers and then conducted a Bayesian inference phylogenetic analysis. We identified 2 oligochaete genotypes: one sister to a clade comprising Limnodrilus udekemianus (Haplotaxida: Naididae) and another sister to Limnodrilus hoffmeisteri. This is the first detection of M. cerebralis from an oligochaete in the SE USA and the first detection of M. cerebralis from an oligochaete other than T. tubifex. These results suggest that other non-T. tubifex definitive hosts can harbor the pathogen and should be considered in the context of fish hatchery biosecurity and monitoring wild trout streams for M. cerebralis and whirling disease in the southeastern USA.

During a survey of myxosporean parasites of marine fish in the coastal region of Vietnam, a species of the genus Henneguya (Myxosporea: Bivalvulida) was found in the gill of yellowfin seabream Acanthopagrus latus (Perciformes: Sparidae). White and oval cysts, measuring 145-220 μm in diameter, were detected in the gill lamellae of 4 of 15 fish examined (26.7%). Mature myxospores were elongate, with smooth valves, two similar polar capsules, and having the following dimensions: spore body length 9.9 ± 0.5 (8.9-12.5) μm, body width 6.7 ± 0.3 (6.1-7.6) μm, thickness 5.1 ± 0.2 (4.8-5.4) μm, caudal appendage length 10.0 ± 1 (8.3-11.6) μm, and total myxospore length 19.3 ± 1.4 (16.5-21.5) μm. The polar capsules were ovoid, measuring 3.2 ± 0.2 (2.8-3.9) μm long and 1.9 ± 0.2 (1.5-2.3) μm wide. Each polar capsule has a polar filament with 4-5 coils. Histological analysis revealed plasmodia in the connective tissues of the gill lamellae, but inflammation and deformation of the gills were not observed. In the phylogenetic tree reconstructed from the small subunit ribosomal DNA (SSU rDNA), sequences of the Henneguya specimens found in this study form a distinct branch. Morphological characteristics and molecular data identified a new species, namely Henneguya lata n. sp.

Fish are prone to several parasitic diseases among which are the myxosporean infections. The goal of this study was to assess the prevalence and patterns of Myxobolus infection in O. niloticus in the Adamawa region of Cameroon. Specimens of Oreochromis niloticus were collected monthly in Mape dam from May 2016 to May 2017, and examined for Myxosporean infections. The overall prevalence was 45.43%. Myxobolus tilapiae significantly exhibited the highest prevalence (15.14%) followed by Myxobolus brachiosaurus (12.29%). Myxobolus pharyngeus (0.86%) was the less prevalent parasite. Out of 350 examined fish, 23.14% were poly infected. Five categories of polyinfections were observed i.e. bi (15.71%), tri (4.00%), tetra (2.29%), penta (1.14%) and hexa specific (0.57%) corresponding to two to six parasite species combinations respectively. Their prevalence dropped significantly with the number of coexisting species whatever the fish sex, class size, infection site and season. Kidneys harbored up to four categories of polyinfections, and Myxobolus tilapiae was the most associated contrary to Myxobolus agolus which appeared only in one combination of the tetra specific infection. Fish were significantly more poly infected during the dry season (28.76%) than the rainy season (18.78%). The polyinfection of O. niloticus with Myxobolus species is an alert calling for urgent control strategies.

Myxozoans of the family Myxobolidae are common parasites in fish. The diversity and ecology of the species of the genus Unicauda are poorly known, which hampers the understanding of the distribution and prevalence of this group of parasites. In the present study, cysts containing parasites whose morphology was consistent with the genus Unicauda were found in the circumorbital region of the ocular conjunctiva of the freshwater fish Moenkhausia grandisquamis Muller & Troschel, 1845 (Characiformes: Characidae) and Triportheus angulatus Spix & Agassiz, 1829 (Characiformes: Triportheidae). The spores have an oval body and long caudal appendage, with a mean total length of 65.2 ± 5.9 μm and width of 5.2 ± 0.7 μm, with two oval and symmetrical polar capsules of 4.9 ± 0.5 μm in length and 1.4 ± 0.2 μm in width, containing polar filaments with five or six coils. An integrated comparative analysis of the morphological characteristics of this parasite and partial sequences of the SSU rDNA gene supported the identification of a new species of histozoic parasite of the genus Unicauda found in fish from the Tocantins River basin, in the eastern Brazilian Amazon region. The new species was denominated by Unicauda tavaresii n. sp.

Made available in DSpace on 2020-12-12T02:22:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 The present study describes Henneguya lacustris n. sp. parasitizing Astyanax lacustris (Lütken 1875), from the Tietê River, State of São Paulo, Brazil, through morphological and molecular analysis. Myxospores of the parasites were found in the gills of A. lacustris with 13% prevalence of infection. The myxospores were oval and presented as measures (mean ± standard deviation): total length 18.3 ± 2.2 μm, body length 10.4 ± 1.6 μm, body width 4.9 ± 0.9 μm, tail length 7.2 ± 2.5 μm. The polar capsule was 4.8 ± 0.3 μm long and 1.5 ± 0.2 μm wide. The polar tubules, present inside the polar capsules, had 6 to 7 turns. The ultrastructural analysis allowed the observation of the asynchronous development of the myxospores. Phylogenetic analysis showed H. lacustris n. sp. as a sister species of H. chydadea Barassa and Cordeiro 2003 in a subclade formed by species that parasitize the gills of Characiform fish from Brazil. Using molecular and morphological characterization, this parasite was identified as a new species of the genus Henneguya Thélohan 1892. Departament of Parasitology Universidade Estadual Paulista “Júlio de Mesquita Filho” – Unesp, R. Prof. Dr. Antônio Celso Wagner Zanin, 250 - Distrito de Rubião Junior Faculdade de Ciências e CIIMAR – Porto Universidade do Porto Programa de Pós-graduação em Análise de Sistemas Ambientais Centro Universitário CESMAC Departament of Parasitology Universidade Estadual Paulista “Júlio de Mesquita Filho” – Unesp, R. Prof. Dr. Antônio Celso Wagner Zanin, 250 - Distrito de Rubião Junior

This study was conducted during the period from March till the end of October 2018, to study the histopathological changes of Myxobolus bramae in kidney tissue of Carasobarbus luteus caught from Tigris River passing through Baghdad city. During the period of this study, a total of 60 fishes belonging to Carasobarbus luteus species from the family Cyprinidae were collected. The prevalence of infection with these protozoa was determinate (5.00%). Histopathological study due to M. bramae in the kidney tissue of C. luteus was done by using three types of stain: Hemotoxylin and eosin, giemsa and acid fast stain to observe plasmodia cyst and structures of spores. These changes characterized by tubular degeneration, necrosis, hyalinization of glomerular tuft, mild distension of Bowman᾿s space with a reduction in haemopoitic tissue together with inflammatory response, and accumulation of melanomacrophages at the site of infection. The results of this study revealed that Carasobarbus luteus from Tigris River at Baghdad city, it infected with Myxobolus bramae and this parasite cause severe histopathological changes in the infected kidneys tissue.

Proliferative gill disease (PGD) caused by the myxozoan Henneguya ictaluri is one of the most damaging diseases affecting U.S. catfish aquaculture. In channel and hybrid catfish, continuous exposure to the actinospore stage of the parasite elicits a destructive branchitis, impairing osmoregulatory and respiratory function. Mortality can reach 100% in severe outbreaks. Despite similarities during acute stages of infection, research indicates arrested development in hybrid catfish, evinced by reduced H. ictaluri sporogenesis and comparably less parasite DNA in hybrid tissues across the developmental timeline. To assess these findings at the pond level, 18, 0.4‐ha ponds were stocked (3,000 fish/pond) with channel (n = 9) or hybrid (n = 9) catfish fingerlings and maintained as monoculture systems for three production cycles, with clean harvests and restocking as warranted. Water was collected monthly for quantitative polymerase chain reaction (qPCR) estimations of H. ictaluri DNA, and sentinel fish were utilized to estimate PGD severity. By the second year, H. ictaluri DNA in hybrid systems was significantly reduced, and PGD lesions in sentinel fish were negligible. Assessment of parasite loads in fish harvested at the termination of the study revealed H. ictaluri DNA in channel catfish to be an order of magnitude higher than hybrid catfish. These results support previous work suggesting that the production of hybrid catfish may reduce PGD incidence in U.S. catfish aquaculture.

In Indian freshwater fish myxosporean infections are among the most cosmopolitan parasites, they are relatively well studied morphologically but their phylogenetic relationships were unclear and the genetic data is limited only to a few species. The study aims to present molecular data for two myxosporean species, Henneguya namae Haldar et al. 1983 and Myxobolus sophorae Jayasri, 1982 collected from Indian freshwater fish, the elongate glass-perchlet Chanda nama (=Ambassis nama) and pool barb Puntius sophore, respectively. In the present study molecular data are provided for H. namae and M. sophorae using nested PCR. The obtained partial 18S rDNA gene sequences were analyzed using maximum likelihood (ML) and Bayesian inference (BI) methods. The 18S rDNA gene sequences of H. namae showed similarity with the sequences of H. chaudhuryi, Henneguya sp. RA-2015, H. voronini and H. setiuensis about 72.1 to 78% and M. sophorae with Myxobolus ticto was about 90% respectively. The aim of this paper was to identify H. namae and M. sophorae morphologically and using molecular methods.

BackgroundHenneguyaThélohan, 1892 (Myxobolidae) is one of the most species-rich genera of myxosporean parasites infecting fish. Although common in nature, there are few reports of these parasites causing important disease in aquaculture. In this paper, we describe a new species ofHenneguyainfectingPagrus major(Temminck & Schlegel), a fish host introduced to the Mediterranean Sea from Japan in the late 1980s.ResultsLarge plasmodia of the parasite were found in the bulbus arteriosus and in the ventricle of the infected fish. Spores were found mainly in the kidney and heart and were accompanied by melanized macrophages or vascular intimal proliferation mixed with a mild non-suppurative response, respectively. Comparisons of morphometric data for spore and polar capsule length and width, suggest a unique combination of features in the newly described species. Molecular analysis, based on18SrDNA sequence of the parasite, followed by phylogenetic analysis, indicated that the parasite described here is a novel species ofHenneguya, clustered with the marine congeneric species.ConclusionsHenneguya aegean. sp. infects in aquacultureP. major, a host introduced as eggs to the Mediterranean from Japan. Despite the high host specificity of the myxobolid parasites,H. aegean. sp. seems to be able to useP. majoras a host and propagate successfully, causing morbidity and mortality. This could result in spillback of the new species from high density cultured non-nativeP. majorto native fish hosts.

Myxosporeans are microscopic cnidarians associated with severe diseases in aquaculture and wild fish populations. This group of parasitic cnidarians thus warrants close attention concerning its potential impact on susceptible fish stocks. At present, little is known about this group of parasites infecting anguillid eels. From myxospore specimens collected from a freshwater eel (Anguilla marmorata) in the Solomon Islands, we describe a new species belonging to the genus Myxobolus based on an integrative taxonomic analysis of morphological, biological traits and molecular data. Furthermore, we determined the phylogenetic position and relationships of this species among other platysporine myxosporeans. Molecular phylogenetic assessment of small subunit ribosomal DNA showed that the species clusters together with Myxobolus portucalensis and Echinactinomyxon type 5 Ozer, Wootten and Shinn, 2002, in a well-supported subclade. This is the first report of a myxosporean parasite infecting fish from the Solomon Islands.

During 9-10 February 2018 and 21-22 February 2020, 7 adult Blue Suckers, Cycleptus elongatus, were collected by hoop nets from the Red River, Little River County (n = 3), and the Black River, Lawrence County (n = 4), Arkansas, and their gills, gallbladders, fins, integument, other major organs, and musculature were examined for myxozoans. All 7 (100%) were infected with an unknown species of gill-infecting Myxobolus sp. Twenty formalin-fixed plasmodia (cysts) of Myxobolus cloutmani n. sp. were elliptoidal, 407 μm long × 270 μm wide. Formalin-fixed myxospores were orbicular to broadly elliptoidal, 8.7 μm long × 7.8 μm wide. Two polar capsules were pyriform and subequal in size, extending over halfway in the myxospore. The larger polar capsule was 5.5 μm long × 3.1 μm wide, while the shorter was 5.1 × 2.9 μm. A coiled polar filament possessed 5 or 6 coils. The myxospore was 3.7 μm thick in sutural view, with a distinct sutural ridge. Qualitative and quantitative morphological data were from formalin-fixed as well as ethanol-preserved spores, while molecular data consisted of a 2,010 base pair sequence of the partial 18S ribosomal RNA gene and a 2,502 base pair sequence of the partial 28S ribosomal RNA gene. Phylogenetic analysis grouped M. cloutmani n. sp. with the other catostomid-infecting myxobolids. This is the first myxozoan reported from C. elongatus.

Two new species of Myxobolus Butschli, 1882 (Bivalvulida: Myxobolidae) are described from the gill of the black redhorse (Moxostoma duquesnei [Leueur][Cypriniformes: Catostomidae]) from the Little Tennessee River Basin, North Carolina, United States. Myxobolus branchiofilum n. sp. infects lumen of the lamellar arterioles and Myxobolus branchiopecten n. sp. infects the bone and cartilage at the tip of the gill rakers. They differ from all congeners by a combination of myxospore dimensions and the presence or absence of an iodinophilic vacuole in the sporoplasm, mucous envelope, intercapsular process, and sutural markings. A phylogenetic analysis of the small subunit ribosomal DNA recovered M. branchiopectin sister to Myxobolus sp. (AF378343) in a clade composed of 6 species of Myxobolus, which infect predominately cypriniform intermediate hosts. Myxobolus branchiofilum was recovered sister to Myxobolus ictiobus Rosser, Griffin, Quiniou, Alberson, Woodyard, Mischker, Greenway, Wise & Pote, 2016 in a clade composed of 8 species of Myxobolus, which predominately infect catostomid intermediate hosts. Histological sections of infected gill revealed intra-lamellar plasmodia of M. branchiofilum in the lumen of the lamellar arterioles and foci of M. branchiopecten developing in the bone and cartilage of the gill raker tip. These are the first myxozoans reported from the black redhorse. Given that these two new species are morphologically congeneric but recovered in distantly related clades, we discuss the persistent issue of myxobolid genera paraphyly/polyphyly.

Between April 2011 and November 2020, 175 individuals of western creek chubsucker Erimyzon claviformis (Girard) (Cypriniformes: Catostomidae) were collected and examined for parasites from 12 sites in the Ouachita, Red, St. Francis, and White river drainages in Arkansas (n = 138 individuals for endoparasites, 22 of same individuals for gill parasites) and from 4 sites in the Red River drainage in Oklahoma (n = 37 individuals for endoparasites, 14 of same individuals for gill parasites). Ninety-nine (57%) were infected with at least 1 parasite, including 2 (6%) of 36 with Piscinoodinium limneticum, 8 (22%) of 36 with 3 different Myxobolus spp., 4 (11%) of 36 with Octomacrum lanceatum, 40 (23%) of 175 with Plagioporus sinitsini, 30 (17%) of 175 with Lissorchis amniculensis, 38 (21%) of 175 with Calientiella etnieri, 3 (2%) of 175 with Isoglaridacris cf. agminis, 10 (6%) of 175 with larval Spiroxys sp., and 1 (0.6%) of 175 with a Neoechinorhynchus sp.; 31 individuals harbored multiple infections. We document several new host and distributional records. Moreover, this report represents only the second published report of the caryophyllid tapeworm C. etnieri since its description more than 46 yr ago.

Made available in DSpace on 2020-12-12T01:46:50Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-12-01 On the basis of morphological and molecular analyses, a new myxozoan parasite is described from the gills of the fish Hoplerythrinus unitaeniatus, collected in the municipality of Nova Xavantina, Mato Grosso State, Brazil. Plasmodia of Henneguya unitaeniata sp. nov. were oval and whitish and were found surrounded by collagen fibers forming plasmodia wall between gill filaments on the gill arch. The spores were ellipsoidal with two similar polar capsules. Morphometric analysis showed a total spore mean length of 23.8 ± 1.5 μm, spore body mean length of 14.5 ± 0.7 μm, caudal appendage mean length of 10.3 ± 1.4 μm, thickness mean length of 4.3 ± 0.3 μm, polar capsule mean length of 4.2 ± 0.5 μm, polar capsule mean width of 1.8 ± 0.3 μm, spore mean width of 4.8 ± 0.4 μm, and 4–5 polar filament coils. Phylogenetic analysis showed Henneguya unitaeniata sp. nov. as a basal species in a subclade formed by myxozoans that parasitize bryconid fishes. Universidade Estadual Paulista (Unesp) Departamento de Parasitologia Instituto de Biociências, Distrito de Ribeirão Junior, Botucatu Laboratório de Ensino e Pesquisa em Animais Silvestres Faculdade de Medicina Veterinária Universidade Federal de Uberlândia Centro Universitário CESMAC Universidade Estadual Paulista (Unesp) Departamento de Parasitologia Instituto de Biociências, Distrito de Ribeirão Junior, Botucatu

A Henneguya sp., morphologically resembling Henneguya nyongensis Fomena & Bouix, 1996, was isolated from the gills of Peter’s elephantnose fish, Gnathonemus petersii Gunther, imported from Nigeria. Plasmodia were located between lamellae and within the gill epithelium, often leading to lamellar fusion. Although slightly smaller, the myxospores from these fish were morphologically consistent with H. nyongensis. In valvular view, spores are elongate, pyriform with a rounded posterior and tapering caudal processes. Myxospore bodies are 9.6–12.3 (mean 11.2) µm long and 4.0–4.7 (mean 4.3) µm wide. Polar capsules are pyriform, elongate, 4.5–5.2 (4.7) µm long and 1.3–1.6 (1.4) µm wide, with a characteristic neck-like structure at the apical end. Sequence generated for the 18S small subunit rRNA gene did not directly match any sequences available on GenBank, but demonstrated 91% nucleotide similarity to an unpublished Henneguya sp. infecting Mormyrus kannume Forsskal. Herein, the description of H. nyongensis is supplemented with new data on histopathology, molecular characterisation, and expanded host and geographical range.

Thelohanellus Kudo, 1933 is a species rich genus of Myxosporea, sharing many morphological similarities with species of Myxobolus but the former possesses a single polar capsule, and the latter has two. Based on molecular phylogenetic analyses, this single distinguishing feature is not monophyletic, and members of Thelohanellus are intermixed with Myxobolus species, calling into question the validity of genus Thelohanellus. The occurrence of two polar capsules in a small proportion of Thelohanellus spores as observed in this study suggests that these species have the capacity to express this Myxobolus-like trait, clouding the distinction of these two genera further. Herein, using the most comprehensive data set to date, we explored the phylogenetic relationships of Thelohanellus to other myxobolids, to investigate the evolutionary history of the genus Thelohanellus and the origins of single polar capsule in this group. The phylogenetic analyses and statistical tests of topology revealed Thelohanellus as a strongly supported polyphyletic lineage, clustering in five distinct branches within Myxobolus clade. Ancestral state reconstruction for polar capsule number showed that Thelohanellus species have evolved from myxosporean species with two polar capsules at least four times, which could be classified in three possible evolutionary pathways. The polyphyly of Thelohanellus and the multiple evolutionary origins of single polar capsule of Thelohanellus demonstrate that the distinction of this genus from Myxobolus is largely for convenience, and does not reflect their evolutionary history., Graphical abstract Image 1, Highlights • Atypical Thelohanellus spores with two polar capsules were firstly observed. • Most myxobolid genera involved including Thelohanellus were poly- or paraphyletic. • Thelohanellus species have evolved at least four times which could be classified in three different evolutionary pathways.

Henneguya oviperda (Cohn, 1895) (Myxozoa: Myxobolidae) is a parasite infecting oocytes of the northern pike Esox lucius Linnaeus, 1758 (Actinopterygii: Esocidae). Infected oocytes are surrounded by all oocyte layers, some of them thinner and less visible than intact oocytes. A mature plasmodium of H. oviperda fills the entire internal space of the oocytes at the secondary growth phase, rendering the nucleus and organelles of the latter undetectable. Apart from the observed degradation of internal structures, alterations in the envelopes of the infected oocytes, and the deformation of the intact oocytes adjacent to them, no other developmental anomalies have been found in the reproductive products of female northern pike. Mature spores of H. oviperda have oval bodies with polar capsules of almost equal size and caudal projections that are on average equal to the spore body length. Phylogenetic analysis comparing 18S rDNA sequences placed H. oviperda into a clade of esocid-infecting species of the genus Henneguya and also supported H. psorospermica as a sister species.

Myxobolus gutturocola n. sp. was isolated from the throat of silver carp, Hypophthalmichthys molitrix, in Chongqing, China. Myxospore valves are unsymmetrical and smooth. Mature spores are ellipsoidal in frontal view, measuring 12.5 ± 0.2 μm (n = 25) in length, 8.4 ± 0.2 μm (n = 25) in width and 7.1 ± 0.2 μm (n = 25) in thickness. Each spore has two pyriform and unequal sizes polar capsules, the large one with 5.7 ± 0.2 μm in length × 3.6 ± 0.2 μm in width and the small one with 4.6 ± 0.2 μm in length × 2.6 ± 0.1 μm in width. Polar filaments are coiled seven or eight turns in the large polar capsule and four or five turns in the small polar capsule. The coils are arranged almost perpendicularly to the longitudinal axis of the polar capsule. Morphological analysis revealed that M. gutturocola n. sp. is distinct from related species of Myxobolus Bütschli, 1882. Molecular analysis has demonstrated that its SSU rDNA sequences do not match with any available sequences in GenBank. Phylogenetic analysis of the SSU rDNA sequences indicated this species clustered in a clade composed exclusively of parasites infecting the fishes of the Leucisini lineage and most closely related to Myxobolus pavlovskii isolated from the gill filaments of silver carp in Hungary.

Myxozoan infections of Indian freshwater fishes are relatively well studied, but their validity is supported with molecular and phylogenetic data only for a few species. The primary objective was to present molecular data for two Myxozoan species, Myxobolus cylindricus and Henneguya gachua collected from Indian freshwater fishes, the dwarf snakehead Channa gachua and the striped dwarf catfish Mystus vittatus, respectively. Various organs of 56 C. gachua and 48 M. vittatus were dissected. Myxozoan plasmodia with mature spores were collected from the gills under a dissecting microscope. Spores obtained from plasmodia from infected hosts were fixed in 80% ethanol in vials and sent for further morphological and molecular examinations to Hungary. The 18S rDNA gene of Myxobolus and Henneguya spp. was amplified using nested polymerase chain reaction (PCR). Phylogenetic analysis was performed using maximum likelihood (ML) and Bayesian inference (BI) methods. Morphological characteristics of M. cylindricus and H. mystasi spores corresponded to the original descriptions made by Sarkar, Mazumdar and Pramanik, 1985 and Haldar, Samal, and Mukhopadhyay, 1997, respectively. Phylogenetic analysis of the 18S rDNA gene revealed that the sequences of M. cylindricus differed from those of most Indian Myxobolus sp., known mostly from cyprinid fishes and formed a subgroup with Myxobolus neurophilus, a parasite of a perciform host, and with Henneguya chaudhuryi, a species belonging to a different genus but described from a closely related channid host. It was also closely related to another Henneguya species, H. lesteri, described from Sillago analis, a coastal fish. Henneguya mystasi had the closest similarity to Henneguya bicaudi, a species described from an Indian cyprinid fish and to Henneguya pellucida reported from a characid fish known from South America. Molecular data received by us gives a solid basis for further identification of these myxozoans, the pathogenicity of which probably plays an economic role at culturing the hosts.

Made available in DSpace on 2021-06-25T10:55:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-08-01 Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Myxozoans are microscopic cnidarians that mainly parasitize fishes. The present study aimed to describe a new myxozoan parasite from the gills of Boulengerella cuvieri (Spix and Agassiz, 1829) by morphological and molecular analysis. The fish was collected in 2019 at the Pindaíba River, municipality of Cocalinho, Mato Grosso State, Brazil. Whitish and circular plasmodia were found in the primary gill filaments, occupying an intralamellar position, with an average of 0.5 mm in diameter. Henneguya Thélohan, 1892 myxospores found inside the plasmodia were elongated and ellipsoidal, consisting of two long and elliptical shell valves with two long, tapering caudal appendages. Morphometric measurements revealed a total spore length of 36.1 ± 2.0 μm; spore body length of 12.8 ± 0.5 μm; spore width of 4.9 ± 0.3 μm; tail length of 23.3 ± 1.6 μm; capsule length of 7.2 ± 0.4 μm; capsule width of 1.5 ± 0.2 μm; and 10 coils in the polar filament. Phylogenetic analysis showed that the isolates from this study were grouped into the main-clade of freshwater fishes, within a group of species parasitizing fishes from Brazil. Intergenotypic difference ranged from 23%–25.9% compared with other Brazilian myxozoan isolates. Using molecular and morphological characterization, this parasite was identified as a new species of the genus Henneguya. São Paulo State University (UNESP) Institute of Biosciences DBBVPZ Section of Parasitology, Rua Professor Doutor Antônio Celso Wagner Zanin, 250, Botucatu Laboratório de Ensino e Pesquisa em Animais Silvestres Faculdade de Medicina Veterinária Universidade Federal de Uberlândia São Paulo State University (UNESP) Institute of Biosciences DBBVPZ Section of Parasitology, Rua Professor Doutor Antônio Celso Wagner Zanin, 250, Botucatu FAPESP: #2016/50377-1 FAPESP: #2018/00754-9 FAPESP: #2018/09623-4 CNPq: #309125/2017-0 FAPESP: 2018/09623-4 FAPESP: 2019/19060-0

We herein document the metazoan parasite component communities of channel catfish (Ictalurus punctatus), blue catfish (Ictalurus furcatus), and their commercially cultured hybrid (female I. punctatus × male I. furcatus) communally stocked as parasite-free fingerlings into each of 3 experimental earthen ponds (each pond harbored channel catfish, blue catfish, and hybrid catfish). The fundamental objective of this work was to test the hypothesis that hybrid catfish exhibit less susceptibility to infection by metazoan parasites than do their parental species. Fingerlings of each catfish species from each pond were parasitologically examined monthly for 1 yr. A total of 112 channel catfish, 74 blue catfish, and 209 hybrid catfish were necropsied; collectively resulting in the detection of 14 metazoan parasite species. Channel catfish had the most diverse component community (12 species: 3 myxozoans, 2 monogenoids, 3 cestodes, 1 nematode, 1 unionid, and 2 copepods) followed by hybrid catfish (11 species: 3 myxozoans, 2 monogenoids, 2 cestodes, 1 nematode, 1 unionid, and 2 copepods) and blue catfish (6 species: 1 myxozoan, 2 monogenoids, 2 cestodes, and 1 copepod). These results do not support the assertion that hybrid catfish are demonstrably more resistant to parasitic infection than either parental species. New host–parasite records herein comprise Corallotaenia intermedia (Fritts, 1959) Freze, 1965, and Corallotaenia parafimbriata (Befus and Freeman, 1973) Scholz, de Chambrier, Mariaux, and Kucha, 2011 for channel catfish; Henneguya sp., C. parafimbriata, and Neoergasilus japonicus (Harada, 1930) Yin, 1956 for blue catfish; and Henneguya adiposaMinchew, 1977, Henneguya bulbosusRosser, Griffin, Quiniou, Khoo, and Pote, 2014, Ligictaluridus mirabilis (Mueller, 1937) Beverley-Burton, 1985, Ligictaluridus pricei (Mueller, 1936) Beverley-Burton, 1984, Essexiella fimbriata (Essex, 1928) Scholz, de Chambrier, Mariaux, and Kucha, 2011, C. parafimbriata, Spiroxys sp., Pyganodon sp., N. japonicus, and Achtheres sp. for hybrid catfish. To our knowledge, this is the most extensive parasitological study of this particular hybrid catfish, or any hybrid catfish, published to date.

Made available in DSpace on 2021-07-14T10:29:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-06-11. Added 1 bitstream(s) on 2021-07-14T11:31:36Z : No. of bitstreams: 1 S1519-69842022000100213.pdf: 986068 bytes, checksum: 0fee8f102ed8dba854ae4eeb6cf3d2ba (MD5) Ibama UFU Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) A mixosporidiose é considerada uma doença infecciosa causada por mixozoários pertentences ao Filo Cnidaria, Classe Myxosporea e Ordem Bivalvulida, considerados parasitos comuns de peixes de água doce e salgada, parasitando vários órgãos, principalmente as brânquias. No presente estudo, 49 espécimes de peixes pertencentes a oito gêneros: Tetragonopterus, Leporinus, Myleus, Pirinampus, Rhapiodon, Pygocentrus, Ageneiosus and Serrasalmus foram coletados e extensões sanguíneas foram feitas com a finalidade de encontrar hemoparasitos. Entretanto, mixoesporos foram observados em cinco (10.20%) espécimes de peixes, pertencentes aos gêneros Tetragonopterus, Myleus e Pygocentrus. Dois morfotipos de Myxobolus spp. foram identificados parasitando esses peixes. Normalmente, as investigações sobre mixozoários em peixes é realizada com a procura de plasmódios ou cistos nos órgãos dos peixes e observação da cavidade de órgãos. Porém, esse trabalho ressalta a importância de se examinar também o sangue desses animais, já que esses parasitos podem ocasionar patogenias severas em peixes. Sendo assim, a análise sanguínea pode proporcionar controle sanatório preventivo para peixes comerciais e evitar perdas econômicas. Myxosporidiosis is an infectious disease caused by myxozoans of the Phylum Cnidaria, Class Myxosporea, and Order Bivalvulida, considered a common parasite in fresh and saltwater fishes that parasitize many organs, especially gills. In the present study, 49 specimens of fishes belonging to eight genera: Tetragonopterus, Leporinus, Myleus, Pirinampus, Rhapiodon, Pygocentrus, Ageneiosus, and Serrasalmus were collected and blood smears were made, fixed with absolute methanol, and stained with Giemsa 10% to survey hemoparasites. However, myxospores were found in the circulating blood of five (10.20%) fishes belonging to genus Tetragonopterus, Myleus, and Pygocentrus. Two morphological types of Myxobolus spp. were identified in all the five fish specimens analyzed. Usually, investigations on myxozoans in fish are carried out with the search for plasmodia or cysts in the fish organs and observation of the cavity of organs. Nevertheless, this study highlights the importance of also examining the blood of these animals, since these parasites can cause severe pathogenic diseases in fish. Thus, the blood analyses can proportionate preventive sanitary control for commercial fish avoiding economic loss. Universidade Estadual Paulista, Instituto de Biociências Universidade Federal de Uberlândia, Faculdade de Medicina Veterinária Universidade Estadual Paulista, Instituto de Biociências Ibama: 60640-1; 52063-3; 17625-4 UFU: 106/15 CNPq: #309125/2017-0; #2018/00754-9; # 2018q09623-4 FAPESP: #2018/09623-4 FAPESP: 2019/19060-0

Made available in DSpace on 2022-04-29T08:30:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-03-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Purpose: We describe two new Henneguya spp. (Myxobolidae) found parasitizing Cyphocharax modestus from Pardo river, Paraná river basin, municipality of Botucatu, São Paulo State, Brazil: Henneguya fastigata n. sp. from gill lamellae and Henneguya pardensis n. sp. from gill arches. We based the descriptions on myxospore morphology, histology, and small subunit ribosomal DNA sequences. Methods: In this investigation, 50 specimens of Cyphocharax modestus were examined between July and December 2020 for myxozoan infections. Morphological characterization was based on the mature myxospores. The small subunit ribosomal DNA sequences were used for molecular and phylogenetic study. Results: Phylogenetic analysis provided the evolutionary position of these new species with other myxobolids species. Myxospores of the two species had similar morphology and morphometrics, but differed in spore body width and length, and ssrDNA sequences differed by 7.2%. These data supported the diagnosis of the parasites as distinct and novel species. The phylogenetic analysis showed a well-supported subclade formed by species that parasitize curimatid fishes, with Henneguya gilbert as a sister species of Henneguya fastigata n. sp., and Henneguya pardensis n. sp. as a sister species of both species. Conclusion: Our analysis was consistent with previous studies suggesting that orders and families of the hosts are strongly correlated with phylogenetic signals in the Myxobolidae. These are the first species of myxozoans described in the Pardo river. Laboratory of Parasitology of Wild Animals Division of Parasitology Institute of Biosciences Universidade Estadual Paulista “Júlio de Mesquita Filho” (UNESP), R. Prof. Dr. Antônio Celso Wagner Zanin, 250, Rubião Junior, SP Programa de Pós-Graduação Em Análise de Sistemas Ambientais Centro Universitário CESMAC, AL Laboratory of Parasitology of Wild Animals Division of Parasitology Institute of Biosciences Universidade Estadual Paulista “Júlio de Mesquita Filho” (UNESP), R. Prof. Dr. Antônio Celso Wagner Zanin, 250, Rubião Junior, SP FAPESP: 2019/19060-0 FAPESP: 2019/26831-2 FAPESP: 2020/05412-9 CNPq: 309125/2017-0