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.     

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 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.     

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.     

Description of Chytridiopsis Trichopterae N. Sp. (Microspora, Chytridiopsidae), A Microsporidian Parasite of the Caddis Fly Polycentropus Flavomaculatus (Trichoptera, Polycentropodidae), With Comments On Relationships Between the Families Chytridiopsidae and Metchnikovellidae

ABSTRACT. The microsporidium Chytridiopsis trichopterae n. sp., a parasite of the midgut epithelium of larvae of the caddis fly Polycentropus flavomaculatus found in southern Sweden, is described based on light microscopic and ultrastructural characteristics. All life cycle stages have isolated nuclei. Merogonial reproduction was not observed. the sporogony comprises two sequences: one with free spores in parasitophorous vacuoles, the other in spherical, 5.6-6.8 μm wide, sporophorous vesicles which lie in the cytoplasm. the free sporogony yields more than 20 spores per sporont. the vesicle-bound sporogony produces 8, 12 or 16 spores. the envelope of the sporophorous vesicle is about 82 nm thick and layered. the internal layer is the plasma membrane of the sporont; the surface layer is electron dense with regularly arranged translucent components. Both spore types are spherical. They have an ～ 35-nm thick spore wall, with a plasma membrane, an electron-lucent endospore, and an ～ 14-nm thick electron-dense exospore. the polar sac is cup-like and lacks a layered anchoring disc. the polar filament is arranged in two to three isofilar coils in the half of the spore opposite the nucleus. the coupling between the polar sac and the polar filament is characteristic. the surface of the polar filament is covered with regularly arranged membraneous chambers resembling a honeycomb. There is no polaroplast of traditional type. the cytoplasm lacks polyribosomes. the nucleus has a prominent, wide nucleolus. the two spore types have identical construction, but differ in dimensions and electron density. Free living spores are about 3.2 μm wide, the diameter of the polar filament proper is 102-187 nm, the chambers of the honeycomb are 70-85 nm high, and the polar sac is up to 425 nm wide. Living spores in the vesicle-bound sporogony are about 2.1 μm wide, the polar filament measures 69-102 nm, the chambers of the honeycomb are about 45 nm high, and these spores are more electron dense. Comparisons of cytology (especially the construction of the spore wall and the polar filament and associated structures) and life cycles reveal prominent differences among the Chytridiopsis-like microsporidia, and close relationships between the families Chytridiopsidae and Metchnikovellidae.     

Light and electron microscopic observations of Leptotheca koreana n. sp. (Myxosporea) in the kidney of cultured rockfish Sebastes schlegeli.

The structure and sporogenesis of Leptotheca koreana n. sp. from cultured rockfish Sebastes schlegeli from South Korea were studied by light and transmission electron microscopy. Broadly oval spores and disporous pseudoplasmodia were observed in the lumen of renal tubules. Spores were 8.59 +/- 1.25 microm in length, 13.42 +/- 1.0 microm in width in sutural view and 8.13 +/- 0.52 pm in thickness in the plane perpendicular to the suture. The width of each valve was always smaller than spore length. Two spherical polar capsules were equal in size (3.86 +/- 0.45 microm in diameter) containing a polar filament with 6 to 7 turns, opening at the anterior end of the spore. Two uninucleate sporoplasms filled the spore cavity. The asynchronous division of secondary and tertiary cells and asynchronous development in spore formation of the present Leptotheca koreana resembled the disporous sphaerosporids. Cytoplasmic projections of pseudoplamodia were considered to be rhizoids, as they seem to strengthen the attachment to the epithelial cells of the renal tubules. The capsulogenic cells in early sporoblast had large amounts of rough endoplasmic reticulum but had a few Golgi apparatus.     

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.     

Ultrastructure of Triangulamyxa amazonica n. gen. and n. sp. (Myxozoa, Myxosporea), a parasite of the Amazonian freshwater fish, Sphoeroides testudineus (Teleostei, Tetrodontidae)

Triangulamyxa amazonica n. gen. and n. sp. (Myxozoa, Ortholineidae), found in the lumen of the intestine of the freshwater fish Sphoeroides testudineus, is described. The fish were collected from the Amazon River near the city of Algodoal, State of the Pará, Brazil. Numerous irregular plasmodia containing different stages of sporogony, including spores, were observed. The plasmodia were lying free in the lumen or had slender pseudopodia-like cytoplasmic processes in contact with intestinal epithelial cells with microvilli projections. Spores, which are equilaterally triangular in valvar view with rounded pointed ends and ellipsoidal in transverse section, are 8.5 μm long, 7.6 μm wide, and 3.8 μm thick. The anterior end of the spores contains two equal drop-shaped polar capsules measuring 2.6 μm in length, each having an isofilar polar filament with 5–6 turns. The characteristics of the spore shape, the spore wall structure and its ridge organization, the plasmodial characteristics and the identity of the host suggest that the parasite is a new genus and species, which is herein designated T. amazonica.     

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.     

Ultrastructure of Tricornia muhezae N. G., n. sp. (Microspora, Thelohaniidae), a parasite of Mansonia africana (Diptera: Culicidae) from Tanzania.

Collections of Mansonia africana mosquito larvae were made at one site in N.E. Tanzania in 1985 and 1987 and from two additional sites, both within about 2 mi of the original one in 1987. An octosporous microsporidian, present at all three sites, was found in both years infecting from 7 to 22% of larvae. Spores (stained in Giemsa) measured 3.0 microns +/- 0.25 microns x 2.25 microns +/- 0.26 microns. Ultrastructurally, spores were seen to have an anterior rim surrounding a depressed area where the endospore was at its thinnest. In transmission electron microscopy section, the rim appeared as two processes into which all layers of the wall extended. At the posterior end all layers of the wall extended into a simple knob-like structure which could be interpreted as a section through a crest running longitudinally around the spore. The polar filament was anisofilar, with two anterior coils of greater diameter than the three posterior coils. Although most closely resembling the genera Amblyspora and Parathelohania in the family Thelohaniidae, the species in M. africana differs from the former, which has oval spores, broadly rounded at the ends, and from the latter, which has a prominent, ridged posterior extension to the spores. The new species has been placed in a new genus and the name Tricornia muhezae proposed.     

Six new species of microsporidia of the genus Amblyospora (Microspora: Amblyosporidae) from blood sucking mosquitoes (Diptera: Culicidae) from the west Siberia

Microsporidia of the genus Amblyospora parasiting the adipose body of mosquito larvae of the genus Aedes and Culex has been studied with both light and electron microscopy. Six new species of microsporidia are described based on ultrastructural characteristics of spores and sporogony stages. Amblyospora flavescens sp. n. Mature spores are egg-shaped. The spore wall with three layers, about 165 nm. Exospore is two-membranous. Subexospore is absent. Endospore is electron-translucent. Polaroplast consists of three parts: lamellar, large vesicular, lamellar. The anisofilar polar filament with 10--11 coils (3 1/2 + 2 1/2 + 4-5). Fixed spores are 6.3 +/- 0.1 x 4.24 +/- 0.1 microm. Amblyospora kolarovi sp. n. Mature spores are egg-shaped. The spore wall with three layers, about 265-315 nm. Exospore shapes tucks on the surface of spore. It is two-membranous. Subexospore is quagge, structural. Endospore is electron-translucent. Polaroplast consists of two parts: lamellar and large vesicular. The anisofilar polar filament with 11-13 coils (3 + 8-10). Fixed spores are 5.4-5.6 x 3.5-4.2 microm. Amblyospora orbiculata sp. n. Mature spores are widely egg-shaped. On a back pole there is a small concavity. The spore wall with three layers, about 155 nm. Exospore is shapes tucks on a surface of spore. It is two-membranous. Subexospore is absent. Endospore is electron-translucent. Polaroplast consists of three parts: lamellar, vesicular, lamellar. Polar filament is anisofilar, with 11 1/2 coils (4 1/2 + 1 + 6). Fixed spores are 6.3 +/- 0.1 x x 4.0 +/- 0.1 microm. Amblyospora rugosa sp. n. Mature spores are egg-shaped. On a back pole there is a small concavity. The spore wall with three layers, about 225 nm. Exospore is shapes tucks on a surface of spore. It is two-membranous. Subexospore is quaggy, structural. Endospore is electron-translucent. Polaroplast lamellate. Polar filament is anisofilar, with 17 1/2 coils (3 1/2 + 1 + 13). Fixed spores are 5.3 +/- 0.1 x 3.7 +/- 0.1 microm. Amblyospora undata sp. n. Mature spores are egg-shaped. The spore wall is three-layered, about 220 nm. Exospore is shapes tucks on a surface of spore. It is two-membranous. Subexospore is quaggy, structural. Endospore is electron-translucent. Polaroplast lamellate. The anisofilar polar filament with 8 coils (3 + 5). Fixed spores are 5.0 +/- 0.1 x 3.0 +/- 0.1 microm. Amblyospora urski sp. n. Mature spores have widely oval form. The back pole is concave. The spore wall with three layers, about 280 nm. Exospore is shapes tucks on a surface of spore. It is two-membranous. Subexospore is quaggy, structural. Endospore is electron-translucent. Polaroplast lamellate. Polar filament is anisofilar, with 6 coils (2 + 4). Fixed spores are 4.4 +/- 0.1 x 2.9 +/- 0.1 microm.     

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.     

Ultrastructure of Tricornia muhezae N. G., N. Sp. (Microspora, Thelohaniidae), a Parasite of Mansonia africana (Diptera: Culicidae) from Tanzania

ABSTRACT. Collections of Mansonia africana mosquito larvae were made at one site in N.E. Tanzania in 1985 and 1987 and from two additional sites, both within about 2 mi of the original one in 1987. An octosporous microsporidian, present at all three sites, was found in both years infecting from 7 to 22% of larvae. Spores (stained in Giemsa) measured 3.0 μ m × 0.25 μ m × 2.25 μ m × 0.26 μ m. Ultrastructurally, spores were seen to have an anterior rim surrounding a depressed area where the endospore was at its thinnest. In transmission electron microscopy section, the rim appeared as two processes into which all layers of the wall extended. At the posterior end all layers of the wall extended into a simple knob-like structure which could be interpreted as a section through a crest running longitudinally around the spore. The polar filament was anisofilar, with two anterior coils of greater diameter than the three posterior coils. Although most closely resembling the genera Amblyspora and Parathelohania in the family Thelohaniidae, the species in M. africana differs from the former, which has oval spores, broadly rounded at the ends, and from the latter, which has a prominent, ridged posterior extension to the spores. The new species has been placed in a new genus and the name Tricornia muhezae proposed.     

Vavraia lutzomyiae n. sp. (Phylum Microspora) infecting the sandfly Lutzomyia longipalpis (Psychodidae, Phlebotominae), a vector of human visceral leishmaniasis

Vavraia lutzomyiae (Microsporida; Pleistophoridae) is a new species parasitic in the tropical phlebotomine sandfly, Lutzomyia longipalpis (Diptera, Psychodidae, Phlebotominae), a major vector of Leishmania chagasi in Latin America where human visceral leishmaniasis is endemic. Infected larvae and pupae were parasitized in the abdomen, and some adults were parasitized in Malpighian tubules and midgut. The sporogonial plasmodium divided by multiple divisions into up to 64 uninucleate sporoblasts. These stages were surrounded outside the plasmalemma by a thick, amorphous dense coat and transformed into a merontogenetic sporophorous vesicle within which the sporonts developed into sporoblasts. The mature microsporidian spores were broadly ellipsoidal and measured 6.1+/-0.43 x 3.1+/-0.15 microm. The spore wall consisted of a transparent endospore (approximately 100 nm) and a thin electron dense exospore (approximately 30 nm) with the outer limit slightly undulated. Spores contained a polar filament arranged peripherally in a single layer of eight to nine wide anterior coils (approximately 125 nm diameter), and three to four narrow posterior coils (approximately 70 nm diameter). Transverse sections revealed a concentric layer organization with the internal layer surrounded by numerous (up to 25) longitudinal microfibrils. The angle of tilt of the polar filament was about 65-68 degrees.     

Supplemental diagnosis of Kudoa funduli (Myxozoa) parasitizing Fundulus heteroclitus (Cyprinodontidae) from coastal northeastern North America

The diagnosis of Kudoa funduli (Hahn, 1915) Meglitsch, 1948 (Myxozoa), is supplemented through study of new material collected from Fundulus heteroclitus (Cyprinodontidae) in coastal waters of Nova Scotia, Canada, and Connecticut. Plasmodia normally develop intracellularly in striated muscle of the flank and head, eventually rupturing and releasing spores. Spores disperse along adjacent epimysium, sometimes as far as the skin surface. Some plasmodia develop extracellularly within the bony cavities of vertebrae. Formalin-fixed spores viewed with a light microscope possess rounded edges, an inconspicuous apical region, thin sutural ridges, measure 6.6-7.4 microm wide, 4.3-5 microm thick, and 5.1-5.4 microm long, and have 4 equally sized polar capsules, 1.7-2.3 microm length by 1.4-1.7 microm width. Scanning electron microscopy revealed that spores are almost stellate, with inconspicuous uplifted tips, and that, within intracellular plasmodia, are embedded in an extensive honeycomb-like matrix. Prevalence of infection of K. funduli was 100% in host populations sampled in both Nova Scotia and Connecticut. Molecular sequence data of the 18S ribosomal DNA (737 base pairs) reveal that K. funduli is a valid species and a member of a clade that includes Kudoa dianae Dyková, Avila, and Fiala, 2002, Kudoa miniauriculata Whitaker, Kent, and Sakanari, 1996, and Kudoa paniformis Kabata and Whitaker, 1981.     

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.     

Leptotheca sparidarum n. sp. (Myxosporea: Bivalvulida), a parasite from cultured common dentex (Dentex dentex L.) and gilthead sea bream (Sparus aurata L.) (Teleostei: Sparidae)

A new myxosporean, Leptotheca sparidarum n. sp., is described from the trunk kidney of two sparid fish, Sparus aurata and Dentex dentex, in several culture facilities from the Western Mediterranean coasts. It is distinguished from all the previously described species by spore morphometrics. Spores with two equal polar capsules and one binucleated sporoplasm. Spore measurements from D. dentex were 5-7.1 micron long x 8.8-12.3 micron thick x 5.88-6.18 micron wide; polar capsules 2.6-3.5 micron in diam. Spore measurements from S. aurata were 5.1-8.24 micron long x 9.41-11.76 micron thick; polar capsules 2.4-3.2 micron in diam. No significant differences were detected between either host. Prevalence could reach 21.4% in D. dentex and 19% in some stock of S. aurata. Renal tubules were the typical site of infection, which was also found in ureters and glomeruli, but seldom in the epiepithelial position of the gut. Spores were formed in disporous sporoblasts, and spore maturation seemed to proceed from the host epithelium towards the lumen. Trophozoites were attached to the host epithelial cells of renal tubules by pseudopodial-like projections, which were inserted into gaps between epithelial cells. Also, cell junctions were observed between primary cells and between neighboring spores.     

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.