Testicular myxosporidiasis in anurans,with a description of Myxobolus fallax n. sp.

During studies of amphibian sperm cryopreservation, a new species of myxosporidean parasite (Myxozoa, Myxosporae) was observed in the testes of the Australian dwarf green tree frog Litoria fallax (Peters). Myxosporidiasis was found to have no affect on L. fallax body condition or sperm numbers. Myxobolus spores from L. fallax are morphologically distinct from Myxobolus hylae spores (infecting the sympatric Litoria aurea Lesson) and the three previously named (exotic to Australia) Myxobolus species found in anurans. Myxobolus fallax n. sp. is characterised by: pseudocyst white, spherical to ovoid, 141 x 74 to 438 x 337 microm in diameter (mature); plasmodium with spores loosely arranged within interior. Spores ovoid 13.4 +/- 0.5 (12.6-14.6) microm length, 9.5 +/- 0.4 (8.3-10.6) microm width, 6.8 +/- 0.4 (6.5-7.6) microm depth, 1.4 +/- 0.1 (1.3-1.6) length/width; polar capsules broadly pyriform and equal in size 4.2 +/- 0.3 (3.3-4.7) microm length, 2.4 +/- 0.2 (2.1-2.8) microm width; filament coils 7-8, wound tightly and perpendicular to the longitudinal axis of the capsule; polar filament 34 +/- 7.0 (18-50) microm length; intercapsular appendix and sutural ridge folds absent; and iodinophilous vacuole and mucous envelope lacking. In addition to this new species, data from archival samples of M. hylae are provided which show two morphologically distinct spore types. Both appeared rarely in the same pseudocysts and we cautiously retain the single species.     

Myxobolus desaequalis n. sp. (Myxozoa,Myxosporea), parasite of the Amazonian freshwater fish,Apteronotus albifrons (Teleostei,Apteronotidae)

Myxobolus desaequalis n. sp. is described from the gill lamellae of the freshwater fish Apteronotus albifrons, collected in the Amazon River, near the city of Salvaterra, Brazil. Large spherical plasmodia filled with disporic pansporoblasts and spores were observed. Ellipsoidal to pyriform spores are 18.3 microm length x 11.2 microm width x 4.4 microm thickness. The anterior end of the spores contain two extremely unequal pyriform polar capsules measuring: (larger): 11.2 microm length, 4.9 microm width, and an isofilar polar filament with 11 to 12 turns obliquely to the longitudinal axis; (smaller): 4.6 microm length, 2.8 microm width, and an isofilar polar filament with 4 to 5 turns, obliquely to the longitudinal axis.     

Myxobolus insignis sp. n. (Myxozoa, Myxosporea, Myxobolidae), a parasite of the Amazonian teleost fish Semaprochilodus insignis (Osteichthyes, Prochilodontidae)

A new myxosporean species is described from the fish Semaprochilodus insignis captured from the Amazon River, near Manaus. Myxobolus insignis sp. n. was located in the gills of the host forming plasmodia inside the secondary gill lamellae. The spores had a thick wall (1.5-2 microm) all around their body, and the valves were symmetrical and smooth. The spores were a little longer than wide, with rounded extremities, in frontal view, and oval in lateral view. They were 14.5 (14-15) microm long by 11.3 (11-12) microm wide and 7.8 (7-8) microm thick. Some spores showed the presence of a triangular thickening of the internal face of the wall near the posterior end of the polar capsules. This thickening could occur in one of the sides of the spore or in both sides. The polar capsules were large and equal in size surpassing the midlength of the spore. They were oval with the posterior extremity rounded, and converging anteriorly with tapered ends. They were 7.6 (7-8) microm long by 4.2 (3-5) microm wide, and the polar filament formed 6 coils slightly obliquely to the axis of the polar capsule. An intercapsular appendix was present. There was no mucous envelope or distinct iodinophilous vacuole.     

Ultrastructural data on the spore of Myxobolus maculatus n. sp. (phylum Myxozoa), parasite from the Amazonian fish Metynnis maculatus (Teleostei)

Light and electron microscopy studies of a myxosporean, parasitic in the intertubular interstitial tissue of the kidney of the freshwater teleost fish Metynnis maculatus Kner, 1860 (Characidae) from the lower Amazon River (Brazil), are described. We observed polysporic histozoic plasmodia delimited by a double membrane and with several pinocytic channels and containing several life cycle stages, including mature spores. The spore body was of pyriform shape and was 21.0 microm long, 8.9 microm wide and 7.5 microm thick. Elongated-pyriform polar capsules were of equal size (12.7 x 3.2 microm) and contained a polar filament with 14 or 15 coils. The spore features fit those of the genus Myxobolus. Densification of the capsular primordium matrix, which increased in density from the inner core outwards, differentiating at the periphery into small microfilaments measuring 45 nm each, and tubuli arranged in aggregates and dispersed within the capsular matrix of the mature spores, are described. Based on the morphological differences and specificity of the host, we propose the creation of a new species named Myxobolus maculatus n. sp.     

A new myxozoan parasite from the Amazonian fish Metynnis argenteus (Teleostei, Characidae): light and electron microscope observations

Myxobolus metynnis n. sp. (Phylum Myxozoa) is described in the connective subcutaneous tissues of the orbicular region of the fish, Metynnis argenteus (Characidae), collected in the lower Amazon River, near the city of Peixe Boi, Pará State, Brazil. Polysporic, histozoic plasmodia were delimited by a double membrane with numerous microvilli on the peripheral cytoplasm. Several life-cycle stages, including mature spores, were observed. An envelope formed by numerous fine and anastomosed microfibrils was observed at the spore surface. The spore body presented an ellipsoidal shape and was about 13.1 microm long, 7.8 microm wide, and 3.9 microm thick. Elongated-pyriform polar capsules were of equal size, measuring 5.2 microm in length, 3.2 microm in width, and possessing a polar filament with 8-9 turns around the longitudinal axis. The binucleated sporoplasm contained a vacuole and numerous sporoplasmosomes. These were circular in cross-section, showing an adherent eccentric, dense structure, with a half-crescent section. Based on the morphological differences and host specificity, we propose that the parasite is a new species named Myxobolus metynnis n. sp.     

Parvicapsula bicornis n. sp. and P. limandae n. sp. (Myxozoa, Parvicapsulidae) in Pleuronectidae (Teleostei, Heterosomata) from Denmark

Two species of Parvicapsula were found in the kidney tubules and the urinary bladder of 2 pleuronectid fish from the northern Oresund, Denmark. The coelozoic, spherical, disporic trophozoites of both species are 10 to 12 pm in diameter. The myxospores of both species are elongate, asymmetrical and slightly curved, and have spherical polar capsules. Parvicapsula bicornis n. sp. (6-8 x 5-6 microm, polar capsule 2.5 microm in diameter) occurs in Pleuronectes platessa. The polar capsules of P. bicornis are arranged symmetrically on either side of the longitudinal axis and its spores differ from other species of Parvicapsula in having two 2-3 microm long posterior processes of different length. Parvicapsula limandae n. sp. (8-11 x 4-5 pm, polar capsule 1.6 microm in diameter) is found in Limanda limanda. The polar capsules are arranged along the longitudinal axis. It differs from Parvicapsula unicornis Kabata, 1962, recorded from L. limanda, in the arrangement of the polar capsules and in the absence of a posterior horn-like projection. The phylogenetic relationship between P. bicornis n. sp., P. limandae n. sp. and other Parvicapsula spp. was examined with their partial small subunit rDNA (SSU rDNA) sequences. P. limandae n. sp. and P. asymmetrica appear to be closely related, while P. bicornis n. sp. and P. minibicornis are the most divergent members of the genus.     

Description of a new species of Myxobolus (Myxozoa: myxobolidae) based on morphological and molecular data

Myxobolus ampullicapsulatus n. sp. was isolated from the gills of Carassius auratus auratus (L., 1758) in Chongqing, China. Myxospores were pyriform, measuring 16.5-19.5 microm long x 8.5-10.0 microm wide x 7.0 microm thick. Two equal polar capsules were ampullaceous, measuring 7.0-10.0 microm long x 2.5-4.0 microm wide, containing polar filaments coiled 9-10 turns. Spore length of this species exceeds that of the majority of other Myxobolus spp., and those overlapping in this dimension can be differentially diagnosed by other characters. Furthermore, the small subunit ribosomal DNA (SSU rDNA) of M. ampullicapsulatus n. sp. is unique among myxozoans sequenced to date. Phylogenetic analyses of the SSU rDNA gene sequence placed this species in a clade composed exclusively of gill parasites, most closely related to Myxobolus longisporus, which also infects the gills of cyprinid fishes in China.     

Sphaerospora ovophila N. Sp. and Myxobolus algonquinensis N. Sp. (Myxozoa, Myxosporea), Ovarian Parasites of Fish from Algonquin Park, Ontario, Canada

ABSTRACT. Sphaerospora ovophila n. sp. and Myxobolus algonquinensis n. sp., found in the ovary of the pumpkinseed ( Lepomis gibbosus ) and the golden shiner ( Noremigonus crysoleucas ) respectively from Algonquin Park, Ontario, are described using light and electron microscopy. Ovoid cysts of S. ovophila measured up to 500 pm in length. Monosporic pseudoplasmodia were ovoid or ellipsoid in shape and measured up to 12.5 pm in length. Spores were 7.2–8.4 pm long × 6.0–7.0 pm wide (in sutural plane) × 7.4–8.2 pm thick (perpendicular to sutural plane), with two subspherical polar capsules of equal size measuring 2.7–3.2 × 2.6–3.1 pm and each of which contained a polar filament with 6–7 coils. The spore had a straight sutural ridge which protruded slightly at the anterior end and contained two uninucleate sporoplasms. The spore valve had ornate folds on the posterior end. Cysts of M. algonquinensis ranged from ovoid to elongated ellipsoid in shape and measured up to 800 pm in length. Mature spores measured 13.G15.7 pm long × 10.1–12.1 pm wide × 5.0–6.9 pm thick. with two pyriform polar capsules of equal size measuring 5.1–5.5 pm × 2.5–2.9 pm, each of which contained a polar filament with 4–6 coils. The spores of M. algonquinensis had smooth valves, a straight sutural ridge and a distinct small intercapsular appendix.     

A new genus Gadimyxa with three new species (Myxozoa, Parvicapsulidae) parasitic in marine fish (Gadidae) and the two-host life cycle of Gadimyxa atlantica n. sp

The myxozoans Gadimyxa atlantica n. sp. and G. sphaerica n. sp., and G. arctica n. sp. (Myxozoa, Parvicapsulidae), are described from Gadus morhua L. and Arctogadus glacialis (Peters) (Gadidae), respectively. They develop coelozoic in bisporic plasmodia in the urinary systems. Two morphological forms of spores were found in all 3 species, i.e., wide and (sub)spherical forms. Both spore types are bilaterally symmetrical along the suture line. The wide spores, semicircular in frontal view and elliptical in apical view, have 2 spherical polar capsules, which open in the sutural or median plane mid on the flat side of the spore. Mean widths of the wide spores of G. atlantica, G. sphaerica, and G. arctica are 7.5, 10.0, and 10.0 microm, respectively. The older, more thick-walled, (sub)spherical spores with binucleate sporoplasm are 8.0, 5.3, and 7.3 microm in mean width, respectively. The mean diameters of the polar capsules of (sub)spherical spores are 2.4, 1.7, and 2.2 microm, respectively. The (sub)spherical forms of Gadimyxa are most similar to Ortholinea within the Ortholineidae, but they differ in the development of the spores and in the arrangement of the polar capsules. The polychaetes Spirorbis spp. (Spirorbidae) act as invertebrate hosts of G. atlantica. The previously described actinospores of the tetractinomyxon type develop to myxospores in Gadus morhua within 8 wk. This is the second known myxozoan 2-host life cycle in the marine environment. Phylogenetic analyses based on partial small subunit rDNA sequences places Gadimyxa spp. among Parvicapsula spp. in the Parvicapsulidae.     

A new species of Myxozoa, Henneguya rondoni n. sp. (Myxozoa), from the peripheral nervous system of the Amazonian fish, Gymnorhamphichthys rondoni (Teleostei)

Henneguya rondoni n. sp. found in the peripheral lateral nerves located below the two lateral lines of the fish Gymnorhamphichthys rondoni (Teleostei, Rhamphichthyidae) from the Amazon river is described using light and electron microscopy. Spherical to ellipsoid cysts measuring up to 110 microm in length contained only immature and mature spores located in close contact with the myelin sheaths of the nervous fibres. Ellipsoidal spores measured 17.7 (16.9-18.1)-microm long, 3.6 (3.0-3.9)-microm wide, and 2.5 (2.2-2.8)-microm (n=25) thick. The spore body measuring 7.0 (6.8-7.3)-microm long was formed by two equal symmetric valves, each with an equal tapering tail 10.7 (10.3-11.0) microm in length. The tails were composed of an internal dense material surrounded by an external homogeneous sheath of hyaline substance. The valves surrounded two equal pyriform polar capsules measuring 2.5 (2.2-2.8)-microm long and 0.85 (0.79-0.88)-microm (n=25) wide and a binucleated sporoplasm cell containing globular sporoplasmosomes 0.38 (0.33-0.42) microm (n=25) in diam. with an internal eccentric dense structure with half-crescent section. Each polar capsule contains an anisofilar polar filament with 6-7 turns obliquely to the long axis. The matrix of the polar capsule was dense and the wall filled with a hyaline substance. The spores differed from those of previously described species. Based on the ultrastructural morphology of the spore and specificity to the host species, we propose a new species name H. rondoni n. sp.     

A new species of myxozoan (Myxosporea) from the brain and spinal cord of rainbow trout (Oncorhynchus mykiss) from Idaho

A new species of Myxosporea, Myxobolus neurotropus n. sp., is described from the brain and spinal cord of rainbow trout (Oncorhynchus mykiss) from Duncan Creek, Owyhee County, Idaho. Spores are oval, have 2 pyriform polar capsules, and possess a thick spore wall (sutural rim) with a short intracapsular offshoot. The mean spore dimensions are length 11.8 microm, width 10.8 microm, and thickness 8.8 microm. This myxozoan is compared to other described Myxobolus species found in cranial tissues of salmonids in terms of spore morphology and phylogenetic analysis. Because it is found in brain and spinal cord, it is encountered while performing screening tests for Myxobolus cerebralis, the causative agent of salmonid whirling disease. Where chronic inflammation and granulomatous lesions are associated with M. cerebralis, histological examination shows no host response to M. neurotropus n. sp. A diagnostic polymerase chain reaction (PCR) test is included as an aid in properly identifying the species.     

Fine structure of the myxosporean,Henneguya curimata n. sp., parasite of the Amazonian fish,Curimata inormata (Teleostei,Curimatidae)

Henneguya curimata n. sp. (Myxozoa, Myxobolidae) is described from the kidney of the teleost Curimata inormata collected in an estuarine region of the Amazon River, near Belém. Brazil. This myxosporean produces large cysts (0.6-1.2 mm in diam.) that represent plasmodia containing all life cycle stages, including spores. The spore body is ellipsoidal (approximately 16.6 microm in length and approximately 6.2 microm in width), and each valve presents a tapering tail (approximately 19.1 microm in length). These valves surround the binucleate sporoplasm cell and two ellipsoidal polar capsules located side-by-side at the same level, measuring 6.5 x 1.2 microm each and containing 10-11 coils of the polar filament. On the basis of its host specificity and on data collected by light and electron microscopy, the organism, H. curimata n. sp. is distinguished as a new species. The taxonomic affinities and morphological comparisons with other similar species of the same genus are discussed.     

Morphological and molecular characterization of a new microsporidian species from the predatory mite Metaseiulus occidentalis (Nesbitt) (Acari,Phytoseiidae)

A new microsporidian species is described from the predatory mite Metaseiulus (formerly Typhlodromus or Galendromus) occidentalis (Nesbitt) (Acari, Phytoseiidae). The ultrastructure of this new species is presented together with the first molecular characterization for a microsporidium of mites. All stages of this new microsporidium are haplokaryotic and develop in direct contact with the host-cell cytoplasm. Sporogony is disporoblastic and spores are formed in eggs, immature stages, and adults of M. occidentalis. There are two morphological classes of spores, one with a short polar filament (3-5 coils) that measured 2.53 x 1.68 microm and one with a longer polar filament (8-9 coils) that measured 3.14 x 1.77 microm. Horizontal transmission of this new species occurs by cannibalism of eggs and other stages and perhaps involves the spores with the long polar filament. Spores with the short polar filament may play a role in autoinfection and vertical (transovarial) transmission that is highly efficient in transferring the microsporidium from adults to progeny. Analysis of the small subunit ribosomal DNA indicated that this species from M. occidentalis is most closely related to the Nosema/Vairimorpha clade of microsporidia. A conflict between the morphological and molecular data is discussed. The species is compared to previously described microsporidia of arachnids resulting in creation of Oligosporidium occidentalis n. sp. in the family Unikaryonidae.     

Morphological and molecular comparison of <Emphasis Type="Italic">Myxobolus procerus</Emphasis> (Kudo, 1934) and <Emphasis Type="Italic">M. intramusculi</Emphasis> n. sp. (Myxozoa) parasitising muscles of the trout-perch <Emphasis Type="Italic">Percopsis omiscomaycus</Emphasis>

Inter- and intracellular cysts from a presumed single species, Myxobolus procerus (Kudo, 1934), parasitising the trout-perch Percopsis omiscomaycus were compared with respect to their spore morphology and small subunit 18S ribosomal DNA. The two cyst types have similar pyriform spores and comparable ranges in spore length and width, size of the polar capsules and number of filament coils. However, fixed spores of the intracellular cysts are significantly shorter (p < 0.05) in mean length than those from intercellular cysts, giving them a broader appearance. Comparing 991 base pairs of 18S rDNA revealed a 20 bp difference between the two cyst types (97.9% similarity), 10 due to base substitutions and 10 due to the presence or absence of a base. The described morphological differences and consistent 2.1% difference in the 18S rDNA reveal that the intracellular form is a separate species, which is described herein as Myxobolus intramusculi n. sp. M. intramusculi n. sp. and M. procerus may be sister species and it is suggested that the two species arose through sympatric speciation involving a switch in site specificity within a single host species.     

Description of Myxobolus gayerae sp. n. and re-description of M. leuciscini infecting European chub from the Hungarian stretch of the river Danube

Myxobolus gayerae sp. n. and M. leuciscini González-Lanza & Alvarez-Pellitero, 1985 (Myxozoa: Myxobolidae) have been described and re-described from European chub Leuciscus cephalus L. from the Hungarian stretch of the river Danube. The ellipsoidal plasmodia of M. gayerae sp. n. were found in the mucosa of the intestinal wall, whereas the large, elongated plasmodia of M. leuciscini infected the afferent arteries of the gill filaments. The spores of M. gayerae sp. n. are relatively large, slightly oval and almost rectangular in shape. On the basis of spore morphology and 18S rDNA sequences, the most similar species was M. cycloides Gurley, 1893, but the 2 species differed in host and tissue tropism as well as in the size of the spores. The spores of M. leuciscini from L. cephalus, having no intercapsular appendix or occasionally a very small one, showed a high morphological similarity to spores collected from L. cephalus cabeda, Chondrostoma polylepis and Rutilus arcasi in Spain and described as M. leuciscini González-Lanza & Alvarez-Pellitero, 1985.     

Myxosporidan parasites for pumpkinseed (Lepomis gibbosus L.) from Ontario.

Five species of myxosporideans were found in pumpkinseed (Lepomis gibbosus L.) from Ryan Lake, Algonquin Park, Ontario. Myxobolus osburni Herrick 1936 was found in pancreatic tissue. Myxobilatus ohioensis (Herrick 1941) Davis 1944 was found in the ureters and urinary bladder. Three new species are described, namely, Myxobolus uvuliferis sp. n. (in the fibrous capsule surrounding the metacercariae of Uvulifer ambloplitis (Hughes 1927), Myxobolus magnaspherus sp. n. (in the parietal peritoneum) and Myxobolus dechtiari sp. n. (in the gills). Myxobolus uvuliferis sp. n. is most similar to M. osburni, but its spores are subspherical and not spherical. Myxobolus magnaspherus sp. n. is most similar to Myxobolus gigas Auerbach 1906, but its spores are wider than long, and they have exceedingly long polar filaments. Myxobolus dechtiari sp. n. is similar to Myxobolus karelicus Petruschewsky 1940 but it lacks an intercapsular appendix.     

Two unusual myxozoans,Kudoa quadricornis n. sp. (Multivalvulida) from the muscle of goldspotted trevally (Carangoides fulvoguttatus) and Kudoa permulticapsula n. sp. (Multivalvulida) from the muscle of Spanish mackerel (Scomberomorus commerson) from the Great Barrier Reef,Australia

Two unusual myxozoan parasites are described from the somatic muscle of 2 reef fishes from Australia's Great Barrier Reef. Kudoa quadricornis n. sp. from the somatic muscle of Carangoides fulvoguttatus is morphologically consistent with other Kudoa sp., having 4 polar capsules and 4 shell valves. Kudoa quadricornis n. sp. is unique in that it has a pyriform spore body with a greater length than width (7.82-9.95 and 5.94-8.66 microm, respectively) and distinct posterolateral projections. Spores of Kudoa permulticapsula n. sp. observed within pseudocysts of the somatic muscle tissue of Scomberomorus commerson are different from those of all other myxozoans. The ovoid spores (length, 4.69-6.65 microm; width, 8.42-9.92 microm; thickness, 6.36-8.33 microm) contain 13 polar capsules with an equal number of shell valves. Phylogenetic analysis using small subunit ribosomal DNA sequences of K. quadricornis n. sp. and K. permulticapsula n. sp. showed that these parasites cluster within a clade comprised of Kudoa species. This brings into question the division of parasites of the Multivalvulida into genera based solely on polar capsule numbers.     

Two new species of Myxozoa, Myxobolus inaequus sp. n. and Henneguya theca sp. n. from the brain of a South American knife fish, Eigemannia virescens (V.)

Two new species of Myxozoa from the brain of the green knife fish Eigemannia virescens are described: Myxobolus inaequus sp. n. has an unusually large spore body and extremely unequal polar capsules, and Henneguya theca sp. n. has an attenuated spore encased in a sheath not previously described in other Myxozoa . Only spores of the two species were observed, and infections caused no obvious pathological changes in the brain.     

Ultrastructural aspects of the myxosporean Henneguya astyanax n. sp. (Myxozoa: Myxobolidae), a parasite of the Amazonian teleost Astyanax keithi (Characidae)

This study reports light and electron microscopical aspects of a myxosporean found in the gills of the freshwater teleost Astyanax keithi Géry, Planquete & Le Bail, 1996 (family Characidae), collected from the estuarine region of the Amazon River, near Belém, Brazil. The prevalence of infection was 23%. In interlamellar spaces of the gills, ellipsoidal whitish cyst-like plasmodia structures were present, which contained spores. The spores had a spermatozoa-like appearance (47.8 +/- 0.71 microm in total length) with a fusiform body (15.2 +/- 0.77 pm in length, 5.7 +/- 0.71 microm in width and 4.2 +/- 0.31 microm in thickness), and each of the 2 valves presented a tapering tail (32.6 +/- 1.11 microm in length). The valves surrounded a binucleate sporoplasm cell and 2 polar capsules (5.0 +/- 0.13 microm in length, 1.5 +/- 0.07 microm in width) that contained 8 to 9 coils of the polar filament. In the sporoplasm, several unique sporoplasmosomes were visible. A synoptic table of spore measurements of known Brazilian Henneguya species is presented. The spores differed from those of previously described species. Based on spore morphology, it is concluded that this species belongs to the family Myxobolidae, genus Henneguya, and that it constitutes a new species: H. astyanax n. sp.