Description of two new gill myxozoans from smallmouth (Micropterus dolomieu) and largemouth (Micropterus salmoides) bass

Two previously undescribed species of myxozoan parasites were observed in the gills of bass inhabiting the Potomac and James River basins. They are described using morphological characteristics and small-subunit (SSU) rDNA gene sequences. Both were taxonomically identified as new species of Myxobolus; Myxobolus branchiarum n. sp. was found exclusively in smallmouth bass, and Myxobolus micropterii n. sp. was found in largemouth and smallmouth bass. Small, spherical, white plasmodia of M. branchiarum from smallmouth bass were observed grossly in the gills; these plasmodia had an average length of 320.3 μm and width of 246.1 μm. The development of the plasmodia is intralamellar in the secondary lamellae of the gills. Mature spores were pyriform in shape with a length of 12.8 ± 1.4 (8.1-15.1) μm and width of 6.9 ± 1.1 (4.0-9.0) μm. Analysis of SSU rDNA identified M. branchiarum in a sister-group to 3 species of Henneguya , although morphologically caudal appendages were absent. Myxobolus micropterii observed in the gills of largemouth and smallmouth bass had larger, ovoid, cream-colored plasmodia with an average length of 568.1 μm and width of 148.1 μm. The cysts developed at the distal end of the gill filament within the primary lamellae. The mature spores were ovoid in shape with a length of 10.8 ± 0.7 (9.2-12.2) μm and width of 10.6 ± 0.6 (9.0-11.8) μm. SSU rDNA analysis placed M. micropterii in a sister group with Henneguya lobosa and Myxobolus oliveirai . The highest prevalence of M. branchiarum was observed in the gills of bass collected from the Cowpasture River (50.9%). Prevalence was 44.6% in bass from the Potomac River and only 4.3% in bass collected from the Shenandoah River. A seasonal study of M. branchiarum , which included both infected and uninfected smallmouth bass, determined that a significantly higher intensity was observed in the spring than in the summer (P < 0.001) or fall (P = 0.004). In an analysis excluding uninfected bass, a higher intensity was observed in the spring than in the summer (P = 0.001) or fall (P = 0.008). Prevalence and seasonal differences were not determined for M. micropterii .     

Unicapsula marquesi n. sp. (Mysxosporea, Multivalvulida) a gill parasite of Polydactylus quadrifilis (Cuvier, 1829) (Pisces, Polynemidae) from the senegalese coast (West Africa)]

Unicapsula marquesi n. sp. (Myxosporea) is described from gill filaments of Polydactylus quadrifilis (Pisces, Polynemidae) obtained from coats of Senegal. The cysts were elongated and their length was 1 to 3 mm. The spores were pyramidal and composed of three valves. Only one of theses valves contained a developed polar capsule measuring 3.01 +/- 0.09 microns in diameter. Length of spore was 6.13 +/- 0.21 microns and the width was 7.18 +/- 0.17. No filament like appendage at the extremity of shell valves. Data on ultrastructure of spores are presented.     

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.     

Morphological,ultrastructural, and molecular analysis of a new species of Myxobolus (Cnidaria,Myxosporea) parasitizing Apareiodon piracicabae (Characiformes,Parodontidae) from Brazil

About forty-two species of Myxobolus have been previously described to parasitize characiform fishes in South America. Here, we described a new myxozoan species, Myxobolus parodontidis n. sp., in the gills of Apareiodon piracicabae (Characiformes, Parodontidae) from the streams of the Middle Paranapanema River basin, Brazil. The proposed new species is supported by a combination of morphological, ultrastructural, and molecular characterization (small subunit ribosomal DNA). Thirteen specimens of A. piracicabae were analyzed and 30.8% was infected by Myxobolus parodontidis n. sp. The myxospores was classified as intralamellar asymmetric type. A few aberrant myxospores with three polar capsules were observed: the spore length and width were the same of normal myxospores, but the polar capsules had smaller sizes. Ultrastructural analysis showed that the plasmodial membrane of Myxobolus parodontidis n. sp. was in direct contact with the host tissue and a connective capsule surrounding the plasmodium was not observed. The phylogenetic analysis showed that the main influence in the clustering of species of myxobolids seems to be related to the phylogenetic relationships established among fish hosts, mainly at the level of family and order. This is the first record of a myxozoan species parasitizing parodontid fish, contributing to the knowledge of the biodiversity of myxozoans from Brazil.     

Thelohanellus bicornei n. sp. Myxosporidie (Myxosporea,Bivalvulida) a gill parasite of Labeo coubie Rüppel, 1832 (Osteichthyen,Cyprinidae) from Burkina Faso,West Africa

Thelohanellus bicornei n. sp. (Myxosporea, Bivalvulida) is described from gill of Labeo coubie (Rüppel, 1832) (Osteichthyen, Cyprinidae) in Burkina Faso, West Africa. The cysts are small and their length is 150 to 350 microns. White, linked together they are rounded shape. The spores are ovoids with smooth valvar surface. Their posterior end is rounded and their anterior part shows two "horns like" expansions. Spores measured 13.5 +/- 0.56 (13-14) microns in length and 8.43 +/- 0.49 (8-9) microns in width. Horns length is 1 to 1.5 microns long. Polar capsule is piriform, it's length is 7.24 +/- 0.45 microns and the width 3.75 +/- 0.32 microns. The polar filament formed 10 turns.     

Comparative morphological and molecular studies on Myxobolus spp. infecting chub from the river Danube, Hungary, and description of M. muellericus sp. n

During a survey on fishes from the River Danube, the occurrence of 8 Myxobolus species (Myxozoa: Myxobolidae) was registered in chub Leuciscus cephalus L. Most species had a specific location within the fish host. M. cycloides was found in the wall of the swimbladder; the branched plasmodia of M. dujardini were located typically in the epithelium of the non-lamellar part of gill filaments; the plasmodia of M. ellipsoides infected fins between 2 fin rays; M. muelleri and Myxobolus sp. 2 formed large elongated plasmodia in the afferent gill artery of filaments, while the round cysts of M. muellericus sp. n. filled the capillary network of the gill lamellae. Intramuscular plasmodia of M. pseudodispar proved to be the most common, although large cysts of Myxobolus sp. 1 were also frequently found in the intestinal wall. Despite similarities of some species in spore morphology, 18S rDNA sequences showed clear differences between the species examined.     

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.     

Novel Myxobolus and Ellipsomyxa species (Cnidaria: Myxozoa) parasiting Brachyplatystoma rousseauxii (Siluriformes: Pimelodidae) in the Amazon basin,Brazil

We describe two novel myxosporean parasites from Brachyplatystoma rousseauxii, an economically important freshwater catfish from the Amazon basin, Brazil. Myxobolus tapajosi n. sp., was found in the gill filaments of 23.5% of 17 fish, with myxospores round to oval in frontal view and biconvex in lateral view: length 15 (13.5–17) μm and width 10.7 (9.6–11.4) μm; polar capsules equal, length 5.8 (4.6–7.1) μm and width 3 (2.3–3.8) μm containing polar tubules with 6–7 turns. Ellipsomyxa amazonensis n. sp. myxospores were found floating freely or inside plasmodia in the gall bladder of 23.5% of fish. The myxospores were ellipsoidal with rounded extremities: length 12.8 (12.3–13.6) μm and width 7.6 (6.7–8.7) μm; with two equal, slightly pyriform polar capsules, length 3.8 (3.8–4.0) μm and width 3.1 (2.5–3.4) μm, containing polar tubules with 2–3 turns. We combined spore morphometry, small-subunit ribosomal DNA data, specific host, and phylogenetic analyses, to identify both of these parasites as new myxozoan species. Maximum likelihood and Bayesian analyses showed that Myxobolus tapajosi n. sp. clustered in a basal branch in a subclade of parasites from exclusively South American pimelodid fishes. Ellipsomyxa amazonensis n. sp. clustered within the marine Ellipsomyxa lineage, but we suspect that although the parasite was collected in freshwater, its hosts perform a large migration throughout the Amazon basin and may have become infected from a brackish/marine polychaete host during the estuary phase of its life.     

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.     

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.     

Myxobolus goensis n. sp. (Myxozoa, Myxosporea, Myxobolidae), a parasite of the gills of Mugil cephalus (Osteichthyes, Mugilidae) from Goa, India

Two species of Myxobolus are reported from the gills of Mugil cephalus collected at Goa, India: M. goensis n. sp. and M. parvus Shulman, 1962. Myxobolus goensis n. sp. forms digitiform or rounded plasmodia between the gill rakers. Their spores are oval in frontal view, with tapered anterior extremity, and lemon-shaped in lateral view, measuring 9.7 (9.5-10.5) microm in length, 6.6 (6-7.5) microm in width, and 5.2 (5-6) microm in thickness. The polar capsules are pyriform and unequal in size. The larger ones are 5.3 (4.5-6) microm long and 2.4 (2-3) microm wide; the smaller ones are 2.4 (2-3) microm long and 1.8 (1.5-2) microm wide. The polar filament forms five turns aligned perpendicularly to the longitudinal axis of the larger polar capsules. Within the smaller polar capsules the polar filament is difficult to observe and, apparently, forms three coils. The spores are distinctly different from other Myxobolus species infecting M. cephalus and other Mugil spp. Furthermore, the present material is also different from 204 Myxobolus species presenting differently sized polar capsules, representing nearly all the known species with this characteristic. The fact that only the M. cephalus specimens were infected among a sample of 206 fish specimens, comprising 27 different species, strongly suggests that this parasite is specific to M. cephalus.     

Description of a new Myxobolus species, M. colossomatis n. sp. from the teleost Colossoma macropomum of the Amazon River basin

Myxobolus colossomatis n. sp. (Myxosporea) is described from a pond-cultured Amazon River fish (Colossoma macropomum). The parasite cysts developed in the connective tissue of the fins, gills, heart, liver and serous membranes around the intestine.     

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.     

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.     

Sphaerospora epinepheli n. sp. (Myxosporea: Sphaerosporidae) observed in grouper (Epinephelus malabaricus)

Sphaerospora epinepheli n. sp. is described from grouper, Epinephelus malabaricus, in cage-cultured and wild fish collected from both coastal lines of southern Thailand. Subspherical to spherical spores and mono- or disporous pseudoplasmodia were observed in the lumen of kidney tubules. Pseudoplasmodia were round to elongate, size range 15.6-22.9 microns (length) x 8.4-21.6 microns (width). Spores were 7.8-10.0 microns (length) x 12.3-14.5 microns (thickness), and 7.0-9.5 microns (width) with two spherical polar capsules of equal size measuring 2.9-4.4 microns in diameter and containing polar filaments with six or seven windings. Two uninucleate sporoplasms showed iodine vacuoles. Blood stages, similar to C-blood protozoans observed from freshwater fish in Europe, were found from peripheral blood smears of grouper. Ultrastructural studies of blood stages showed a similar structure to unidentified mobile protozoans from the blood of carp. Electron dense bodies were observed in the cytoplasm of the primary cell blood stages. Infected proximal-tubular epithelial cells showed highly vacuolated cytoplasm and pycnotic nuclei.     

Myxobolus absonus sp. n. (Myxozoa: Myxosporea) parasitizing pimelodus maculatus (siluriformes: Pimelodidae), a South American freshwater fish

A new myxoporean species is described from a freshwater fish in Brazil. Myxobolus absonus sp. n. was found infecting Pimelodus maculatus captured in the river Piracicaba, State of S?o Paulo, Brazil. Cysts were found free in the opercular cavity. The spores are large (length--15.7 +/- 1.5 microns, width--10.2 +/- 0.7 microns; mean +/- S.D.) and oval in shape, with the anterior end slightly pointed. The spore valves are relatively thin, smooth, and asymmetrical in a frontal view. The polar capsules are pyriform in shape, and unequal in size; the largest are 6.4 +/- 0.7 microns long and 3.6 +/- 0.5 microns wide, while the smallest are 4.2 +/- 0.6 microns long and 2.5 +/- 0.5 microns wide.     

Phylogeny, ultrastructure, histopathology and prevalence of Myxobolus oliveirai sp. nov., a parasite of Brycon hilarii (Characidae) in the Pantanal wetland, Brazil

This paper presents the morphological, histological and ultrastructural characteristics of Myxobolus oliveirai sp. nov., a parasite of the gill filaments in Brycon hilarii from the Brazilian Pantanal. Out of 216 B. hilariispecimens examined (126 wild and 90 cultivated), 38.1% of wild specimens (n = 48) were infected. The parasites form elongated plasmodia primarily in the tip of gill filaments, reaching about 3 mm in length. A thorough comparison with all the Myxobolus species described from South American hosts, as well as nearly all the Myxobolus species described so far is provided. Partial sequencing of the 18S rDNA gene revealed a total of 1,527 bp. The Myxobolus species parasite of B. hilarii did not match any of the Myxozoa available in GenBank. In the phylogenetic analysis, M. oliveirai sp. nov. composed a monophyletic group with eight other species: five species of Myxobolus parasites of mugilid fishes, two parasites of pangasiid and one of centrarchid. Infection prevalence values of the parasite revealed no significant differences between wet and dry seasons or between males and females. The importance of the infection to the farming of the host species is emphasized.     

Entamoeba bubalus, n.sp., from Carabao

SUMMARY. Twelve carabao in the Philippines were found to be lightly infected with intestinal amoebae. Trophic forms (12 microns in diameter) of this protozoan possessed a definite ectoplasm and a homogeneous endoplasm. They were found only in stained preparations. The nucleus was similar to that of the cyst. All unconcentrated fecal smears contained at least a few cysts (8 microns in diameter). In these forms the cytoplasm usually contained a large vacuole and one or more irregular chromatoidal bodies. The nucleus (2.6 microns in diameter) possessed a pronounced, deeply staining, uniform peripheral ring and a large irregular endosome. There was no periendosomal ring. This amoeba is designated as Entamoeba bubalus , n.sp.     

Life history, pathology, and description of Kudoa ovivora n. sp. (Myxozoa, Myxosporea): an ovarian parasite of Caribbean labroid fishes

We describe Kudoa ovivora n. sp. from ovaries of bluehead wrasse, Thalassoma bifasciatum, and record its presence in 6 species (Labroidei) collected in the San Blas Islands. Panama. Kudoa ovivora spores are quadrate with rounded edges in apical view, oval-shaped with apical valve extensions in side view (mean spore dimensions: length 6.5 microns, width 7.7 microns, thickness 6.9 microns; mean polar capsule dimensions: length 2.1 microns, width 1.5 microns). This is the first Kudoa species from gonads of fishes. Prevalence of infection varied among labrids (Thalassoma bifasciatum, Halichoeres bivittatus, Halichoeres garnoti, Halichoeres poevi), with T. bifasciatum exhibiting the greatest prevalence. Density of infection, measured as percent infected eggs, also varied among species with highest densities occurring in H. garnoti. Kudoa ovivora may not require an intermediate host because fishes fed infected tissue developed more infections than unfed fish. Infected eggs are inviable and larger and heavier than uninfected eggs. Infected eggs contain more organic and inorganic material, indicating that K. ovivora increases resource allocation to eggs. Therefore, infected females may have reduced growth, fecundity, and/or spawning activity. Because males were uninfected and all identified hosts are protogynous sequential hermaphrodites, further studies of K. ovivora may provide new insights on the costs/benefits of sex change.     

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.