Valvular View Research Articles

The description of Myxobolus meijiangensis n. sp. (Myxozoa: Myxobolidae) and its pathogenicity to the gills of goldfish.

Myxobolus Bütschli, 1882 is the most speciose myxozoan genus, although some species have only been described according to the morphological characteristics of spores. In the present study, a new Myxobolus species infecting the gill lamellae of goldfish from Chongqing, China, was described using a comprehensive analysis of morphological, molecular, and histological data. Mature spores were flat-pear in valvular view with tapering anterior and rounded posterior ends, measuring 11.0±0.4 (10.4-11.6) μm in length and 10.3±0.3 (9.6-11.0) μm in width. Two equal-sized elongate pyriform polar capsules were 5.6±0.6 (4.5-6.4) μm long and 3.5±0.5 (2.4-4.1) μm wide. Polar tubules were coiled with 8 or 9 turns. The small-subunit ribosomal DNA gene sequence length of the present species was 1951nt, and the highest similarity was 97.99% with M. pyramidis. Comparative analysis of the morphological and molecular data revealed that the present species was distinct from other known myxosporeans. Plasmodia were located at the interlamellar troughs nearing the top of the primary gills. Infection by the present species destroyed the original structure of gill lamellae and caused an inflammatory response, eventually leading to fish dyspnea. The morphological, molecular, and pathological data from the present study can be used for aquaculture since they provide guidance for easy detection and future control of this myxosporidiosis.

First report of a histozoic Henneguya (Cnidaria, Endocnidozoa) infecting a synbranchid potamodromous fish from South America: Morphostructural and biological data

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.

Morphological and Molecular Characterization of Myxobolus planilizae n. sp. (Cnidaria; Myxosporea; Myxobolidae) Infecting the Largescale Mullet Planiliza macrolepis (Smith, 1846) Collected From Cochin Backwaters, India.

Myxobolus planilizae n. sp. is described from the intestinal muscles of the largescale mullet Planiliza macrolepis from Cochin backwaters, Kerala, India. Host fishes inhabiting Cochin backwaters were collected using Chinese nets/gill nets. The morphometry and morphological studies were carried out using Nomarski differential interference contrast (DIC) optics, followed by molecular and phylogenetic analyses of the small subunit ribosomal DNA gene (SSU rDNA). Plasmodia small, pale white, and infect the muscles of the intestine; measured 0.13-0.22 (0.17) × 0.09-0.14 (0.13) mm. Mature myxospores pyriform in valvular view, and biconvex in sutural and apical views with a short anterior extension, and measured 7.45-8.75 (8.40) × 6.04-6.86 (6.25) µm. Shell valves with sutural ornamentations. Polar capsules two, equal, pyriform, measured 3.96-4.54 (4.45) × 2.22-2.94 (2.52) µm. Polar filament arranged in five coils, measured 24.41-34.44 (28.52) µm when extruded. In morphological and morphometric analysis, the present species exhibit remarkable variations from other species of the genus Myxobolus. In molecular analysis, the present species revealed the highest identity of 91.85% and divergence of 9.95% with related species, underlining its molecular uniqueness. In phylogenetic analysis, species of Myxobolus infecting mullets appeared as a separate clade and the present species was positioned distinctly with a high bootstrap value. Based on morphology, morphometry, and molecular and phylogenetic analyses, along with tissue/host specificities and geographic location, the present parasite is treated as new and is reported here as M. planilizae n. sp.

Ultrastructure, surface topography, morphology and histological observations of a new parasitic cnidarian of the marbled swamp eel from the world's largest tropical wetland area, Pantanal, Brazil

Myxosporeans are a diverse group of microscopic cnidarians of wide distribution that evolved into a parasitic lifestyle. A new myxosporean species, Myxobolus sp., is herein described infecting the mandible of wild specimens of Synbranchus marmoratus, caught in the world's largest tropical wetland area, Pantanal, Brazil. Light, scanning, transmission electron microscopy and histological observations unveiled detailed taxonomic information of the new myxosporean cnidarian. Ultrastructural analysis revealed a detailed description of plasmodia structures which can be used for comparison with plasmodia from other species of myxobolids. Both histological and ultrastructural observations evidenced a connective tissue capsule surrounding the plasmodia of Myxobolus sp. as a histopathological host reaction to the infection of this parasitic cnidarian. Histology showed that tissue tropism of the new myxosporean occurs in a well-defined part of the mandible, with development of plasmodia occurring in the epidermis layer. Mature myxospores from the valvular view featured an ovoid shape and had a short prolongation of the spore valves in the posterior end. Myxospores measured 22.7 ± 1.2 µm (21.5–23.9 µm) in length, 12.5 ± 0.4 µm (12.1–12.9 µm) in width and 11.3 ± 0.5 (10.8–11.8 µm) in thickness. Polar capsules were pyriform equally-sized and measuring 4.6 ± 0.3 µm (3.9–4.3 µm) in length and 2.9 ± 0.1 µm in width (2.8–3.0 µm). Finally, this study substantiates the still hidden myxosporean diversity from South America.

Sphaeromyxa azevedoi n. sp. (Myxozoa: Sphaeromyxidae) infecting the gall bladder of Gobioides grahamae (Perciformes: Gobiidae) in the Amazon region.

Sphaeromyxa azevedoi n. sp. is described from the gall bladder of the goby Gobioides grahamae (Gobiidae) captured on the Paracauari River in Salvaterra, on Marajó Island, northern Brazil. A total of 50 G. grahamae specimens were analysed, and 15 (30%) were parasitised by the plasmodia and myxospore of Sphaeromyxa azevedoi n. sp. Large plasmodia were observed floating in the bile. These plasmodia were flat, rounded, oval or elongated, and of varying sizes. The mature myxospores, found singly or in pairs, were 27.1 ± 2.7 (20.5-30.1) μmLength and 3.8 ± 0.2 (3.5-4.4) μmWidth in the valvular view. The myxospore has two polar capsules of equal size, 8.1 ± 0.6 (7.4-9.4) μm in length and 2.9 ± 0.2 (2.3-3.3) μm in width. A polar tubule was observed in each capsule, arranged perpendicularly to the principal axis, with three or four coils. The histological analysis showed that the plasmodia and myxospore are located in the lumen of the gall bladder, arranged in pairs, and the epithelium of the gall bladder presented multifocal necrosis. The SSU rDNA of Sphaeromyxa azevedoi n. sp. clusters in the 'balbianii' group of the Sphaeromyxa clade. The morphological characteristics and molecular phylogeny of Sphaeromyxa azevedoi n. sp. support its classification as a new species of the genus Sphaeromyxa, which represents an important advancement in the understanding of the diversity of the myxozoan parasite fauna of Brazilian fishes, especially considering that the new species may be detrimental to the host, a commercially important Brazilian fish species.

Description of Myxidium pseudocuneiforme n. sp. (Myxosporea: Myxidiidae) from Cyprinus carpio in China, with the resolution on a taxonomic dilemma of Myxidium cuneiforme.

Investigations on myxozoan parasites of fish from Chongqing in China, revealed two Myxidium cuneiforme-like myxosporeans infecting the gallbladder of Cyprinus carpio carpio and Carassius auratus. We researched their myxospore morphology, and analyzed their genetic similarity and phylogenic relationships to other myxozoans based on small subunit ribosomal DNA (18S rDNA) sequences. Although both parasites recovered were morphologically similar, the myxosporean isolated from C.auratus was consistent in morphology to Myxidium cuneiforme, which was described from this host species. The parasite isolated from C. c.carpio had overlapping myxospore dimensions to M.cuneiforme, but on average, the polar capsules were not as long. More importantly, this parasite was genetically distinct from M.cuneiforme with 96.3% and 96.5% similarity in two sequences of 18S rDNA, and we propose the name Myxidium pseudocuneiforme n. sp. for this myxozoan from common carp. Its mature myxospores are ellipsoidal and asymmetric with pointed ends in valvular view, arc-shaped or fusiform in sutural view. The pyriform polar capsules are equal in size, and polar filament with 5-6 coils. This study highlights that molecular characteristics and host specificity are indispensable for myxozoan species identification when presented with the taxonomic dilemma of whether we are observing one species that exhibits slight morphological differences or multiple, but similar, species in different hosts.

A new myxozoan parasite, Myxobolus allami sp. n. (Myxozoa: Myxobolidae) from the intestinal wall of Sparidentex hasta (Valenciennes) in Arabian Gulf.

Myxobolus allami sp. n. is described from the intestinal wall of the silvery black porgy, Sparidentex hasta (Valenciennes), off Saudi Arabian coast of Arabian Gulf. Two of 20 examined fish were found to be infected with irregular-shaped plasmodia 3-8 mm long × 2-3 mm wide. Mature myxospores are subspherical to elliptical in the valvular view and oval in the sutural view, and are 11-13 (12) µm long, 7-8 (7.5) µm wide and 10-12 (10.8) µm thick. Spores have relatively thin valves and mostly (~ 72%) end with short caudal appendages of ~3 µm long. The spores also have two polar capsules, which are oval to elliptical and measure 5-7 (5.7) µm in length and 2-3 (2.7) µm in width. Polar filaments are coiled, with three turns. Transmission electron microscopy revealed that caudal appendages originated from the sutural edge at the posterior pole of the myxospore with density similar to that of its valves. The SSU rRNAgene sequence of the present species does not match any available sequences in GenBank. Phylogenetically, this species is sister to Myxobolus khaliji Zhang, Al-Qurausihy et Abdel-Baki, 2014 within a well-supported clade of Myxobolus-Henneguya with species infecting marine fishes. The combination of molecular data and morphological differences between this and other species of Myxobolus Bütschli, 1882 lead us to propose that the present form be established as a new species, M. allami. The present study also provides more evidence for the idea that caudal appendages cannot be reliably used to distinguish the species of the genera Myxobolus and Henneguya Thélohan, 1892.

Morphological and molecular description of a new species of Myxobolus (Myxosporea: Myxobolidae) infecting Planiliza macrolepis (Smith, 1846) from India.

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 × 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 filamentswith 4 coils, measured 29.61 ± 4.75μm in length when extruded. Sporoplasm binucleate with a rudimentary nucleus and a vacuole. A comparison with related Myxobolus species revealed significant morphological and 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 Inference 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.

Henneguya michiganensis n. sp. (Cnidaria: Myxosporea) from the gills of muskellunge Esox masquinongy Mitchill(Esociformes: Esocidae)

Henneguya Thélohan, 1892is the second most species rich genus of myxozoans, with reports from freshwater and marine fish worldwide. In the Great Lakes region of North America, muskellunge Esox masquinongy is an important game fish species that serves as an apex predator in the ecosystems of many inland lakes. The myxozoan fauna of esocid fish, especially muskellunge, remains largely understudied. During fish health assessments, muskellunge were examined for parasitic infections and myxozoan pseudocysts were observed on gill clip wet mounts. When ruptured under pressure, the intralamellar pseudocysts released thousands of myxospores consistent with those of the genus Henneguya. The myxospores were 67.3-96.6 (79.1 ± 5.9) µm in total length. The spore body was 18.6-22.6 (20.9 ± 1.0) µm × 5.4-6.9 (6.3 ± 0.4) µm in valvular view and 3.5-4.0 (3.8 ± 0.3) µm wide in sutural view. The two pyriform polar capsules positioned at the anterior of the spore body were 6.4-7.7 (7.0 ± 0.4) µm × 1.8-2.1 (2.0 ± 0.1) µm and each contained a tightly coiled polar filament with 9-10 turns. Two tapering caudal processes extended from the posterior of the spore body and were 47.3-75.6 (58.3 ± 5.8) µm in length. Histologically, large intralamellar polysporic plasmodia were surrounded by plump pillar cells and a distinct layer of plasma. Mild inflammation was present peripherally, with small numbers of necrotic germinative cells and intraplasmodial phagocytes internally. Ribosomal 18S rRNA gene sequence data were obtained from three gill pseudocysts. The three ~2000-bp sequences were identical, but shared no significant similarity with any publicly available sequence data. Phylogenetic analyses demonstrated sequence data from this Henneguya fell within a well-supported clade of Henneguya spp. reported from northern pike Esox lucius in Europe. Based on the distinct morphological, histological and molecular data, this species is designated as Henneguya michiganensis n. sp. from muskellunge in Michigan, USA.

Zschokkella epinepheli n. sp. (Myxosporea: Myxidiidae) infecting the gallbladder of the white grouper Epinephelus aeneus (Serranidae) from Tunisian waters.

A new coelozoic myxosporean species, Zschokkella epinepheli n. sp., collected from the gallbladder of the white grouper Epinephelus aeneus (Perciformes: Serranidae) from the bay of Bizerte, Tunisia, is described based on morphological and molecular characteristics. Myxospores and plasmodia were observed floating free in the bile. Mature plasmodia were polysporic and subspherical in shape, measuring 85.0-94.0μm long and 70.0-82.0μm wide. Mature myxospores were ovoid in valvular view, measuring 10.0 ± 1.7 (8.0-11.0) μm in length and 7.0 ± 0.3 (6.6-7.5) μm in width. Polar capsules were pyriform and equal in size, measuring 3.0 ± 0.2 (2.8-3.6) μm in length and 2.3 ± 0.3 (1.8-2.7) μm in width. Myxospore valves had 12-14 longitudinal striations. Based on the small subunit rDNA, the new species Z. epinepheli n. sp. differs from all other Zschokkella species for which there is a DNA sequence deposited in GenBank. Phylogenetic analysis revealed that Z. epinepheli n. sp. clustered in the marine subclade of Zschokkella species within the biliary tract IV clade. This is the first report of a Zschokkella species from the gallbladder of an epinephelin fishes.

Necroulcerative dermatitis associated with Myxobolus dermatoulcerans n. sp. (Cnidaria: Myxobolidae) in red-bellied piranha, Pygocentrus nattereri Kner (Characiformes: Serrasalmidae), from Peru.

A group of red-bellied piranha, Pygocentrus nattereri Kner, recently imported from Peru exhibited multifocal, cutaneous ulcerations with exposure of the underlying musculature. Skin scrapes yielded moderate numbers of myxospores morphologically consistent with Myxobolus Bütschli, 1882. Myxospores from these fish were morphologically and molecularly distinct from other myxobolids infecting piranha. Myxospores are pyriform to capsular with a rounded posterior and slightly rounded to tapering anterior aspect in valvular view. Myxospore bodies are 14.3-17.8 (mean 16.1) µm long and 7.6-10.3 (mean 8.9) µm wide. Polar capsules are symmetrical, slender, elongate, and measure 7.4-10.2 (mean 9.2) µm long and 2.1-3.7 (mean 3.0) µm wide. Sequence generated for the 18S rRNA gene had no direct matches to any sequence available on GenBank but demonstrated less than 89% nucleotide similarity to various published and unpublished Myxobolus spp. from Piaractus brachypomus (Cuvier) and Colossoma macropomum (Cuvier). This paper provides the morphological and molecular characterisation of Myxobolus dermatoulcerans n. sp. from red-bellied piranha and describes associated pathological lesions.

Characterisation of Myxobolus stellatus n. sp. (Cnidaria: Myxobolidae) infecting the cranial nerves and ganglia of the spotfin hatchetfish Thoracocharax stellatus (Kner) (Characiformes: Gasteropelecidae) from Colombia

A previously undescribed Myxobolus sp. was isolated from the cranial nerves and ganglia of the spotfin hatchetfish Thoracocharax stellatus (Kner) that exhibited neurologic signs following importation from Colombia. Associated plasmodia formed space-occupying masses within nerves, compressing neuronal cell bodies and causing axonal degeneration. Myxospores from these fish were morphologically and molecularly distinct from other myxobolids infecting the central nervous system of characins. In valvular view, spores are pyriform with a rounded posterior and tapering anterior aspect. Myxospore bodies are 17.0-19.4 (mean 18.4) µm long and 8.2-9.3 (mean 8.8) µm wide. Polar capsules are asymmetrical and pyriform with a neck-like projection at the apical end. The small polar capsule measures 4.3-5.9 × 2.2-3.1 (mean 5.0 × 2.6) µm, while the large polar capsule measures 9.1-10.7 × 4.9-6.3 (mean 9.9 × 5.4) µm wide. The sequence generated for the small subunit rRNA (18S) gene did not directly match any sequences available on GenBank, but demonstrated 92% nucleotide similarity to Myxobolus axelrodi Camus, Dill, Rosser, Pote & Griffin, 2017 infecting Paracheirodon axelrodi (Schultz). This study provides the first morphological, histological and molecular characterisation of Myxobolus stellatus n. sp. from the spotfin hatchetfish.

Characterization of Myxidium spinibarba sp. nov. (Cnidaria, Myxosporea, Myxidiidae) from Spinibarbus sinensis (Bleeker, 1871) in Chongqing China.

In the present study, we described a new species of Myxidium Bütschli, 1882, obtained from the gallbladder of Spinibarbus sinensis (Bleeker, 1871) from the Jialing River in Chongqing, China. Myxidium spinibarba sp. nov. was identified based on morphological and SSU rDNA sequence data. The mature myxospores were fusiform in valvular view and ovoid in sutural view, with somewhat protrusive poles and mean dimensions (all in μm) of 11.8 ± 0.5 (10.6-12.4) in length and 6.1 ± 0.5 (5.5-7.2) in width. The polar capsules were pyriform and equal in size with mean dimensions of 3.6 ± 0.4 (3.0-4.4) in length and 3.0 ± 0.2 (2.7-3.2) in width. The new species was distinct from related species of Myxidium in its morphology and molecular characteristics. Phylogenetic analysis indicated the clustering of species based on the presence or absence of valvular striations. Moreover, myxospore morphology, rather than the host environment, played an important role in the partial phylogenetic clustering.

Two Novel Myxozoans from Pirate Perch Aphredoderus sayanus (Gilliams, 1824) in the Upper Mississippi River, Including the First North American Species of Hennegoides Lom, Tonguthai, & Dyková, 1991

The pirate perch Aphredoderus sayanus is a relatively small fish species found in rivers throughout much of the eastern United States. Due to their cryptic nature, relatively little is known regarding their parasite fauna. A survey of pirate perch from the upper Mississippi River revealed 2 novel myxozoans. Hennegoides flockae n. sp. was observed in heavily infected gills where the lamellae featured irregular expansion by bulbous myxozoan polysporic plasmodia, typically affecting the middle to distal half of the filaments. When severe, infection of sequential filaments was such that the filaments were fused, forming what appeared as multicystic/lobular parasitic aggregates subdivided by fine epithelial cords. The total myxospore length of Hennegoides flockae was 35.4-46.4 (41.3 ± 3.3) and the spore body, asymmetrically ovoid in valvular view, was 15.4-18.7 (17.0 ± 0.7) × 7.1-8.7 (7.9 ± 0.4). Henneguya marcquenskiae n. sp. was observed in the liver with plasmodia present randomly and infrequently in the hepatocellular parenchyma. The total myxospore length for Henneguya marcquenskiae was 39.5-55.9 (48.4 ± 4.2), with the spore body being lanceolate, 13.9-16.5 (15.4 ± 0.7) × 7.1-9.0 (8.3 ± 0.5). Phylogenetic analysis of the SSU rRNA gene placed both Hennegoides flockae and Henneguya marcquenskiae as sisters to each other in a clade containing other Myxozoans known to infect the gills of esocids, percids, and centrarchids. These parasites represent the first reports of Henneguya and Hennegoides from pirate perch, with the latter being the first report of this genus outside of the Asian continent.

A morphological, molecular, and histopathological redescription of Henneguya nyongensis Fomena & Bouix, 1996 (Cnidaria: Myxobolidae) infecting the gills of Peter's elephantnose fish, Gnathonemus petersii (Günther) (Osteoglossiformes: Mormyridae), imported from Nigeria.

A Henneguya sp., morphologically resembling Henneguya nyongensis Fomena & Bouix, 1996, was isolated from the gills of Peter's elephantnose fish, Gnathonemus petersii Günther, 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 Forsskål. Herein, the description of H. nyongensis is supplemented with new data on histopathology, molecular characterisation, and expanded host and geographical range.

First molecular evidence of Thelohanellus wallagoi Sarkar, 1985 (Myxozoa) from economically important food fish, freshwater shark Wallago attu (Siluridae) in India

The freshwater shark Wallago attu (Bl. and Schn.) is a frequent silurid in the River Ganga and one of the most commercially exploit fish in India. In a survey on its infection with myxosporeans, spore type belongs to Thelohanellus species was found in the gills, kidney and intestine respectively. Through morphological and molecular investigations, we identified the spore as Thelohanellus wallagoi Sarkar, 1985. They were pyriform in valvular view and slim in sutural view, and had one pyriform polar capsule with four to five turns. The spores measured 8.0 × 4.0 × 2.3 μm. T. wallagoi developed in small cysts in the gill lamellae, whereas cyst and scattered spores of T. wallagoi were also found in the kidney and intestine respectively. The 18S rDNA sequence of T. wallagoi isolates recovered from gills, kidney and intestine were found similar to each other and differed from any other Thelohanellus species available in GenBank and validated its status after 32 years of original description. Phylogenetic analysis signified that T. wallagoi was placed sister to Myxobolus species in the clade that indicated the polyphyletic nature of the genus Thelohanellus.

A new pathogen, Myxobolus holzerae (Myxosporea: Myxozoa) causing severe gill disease in an Indian major carp Labeo rohita in a cold water wetland, Punjab (India)

The Indian major carp, Labeo rohita Hamilton, 1822 is a tropical freshwater cyprinid fish native to inland waters in Asia. Herein, we describe a novel myxozoan forming plasmodia in the gill lamellae of L. rohita from Ranjit Sagar Wetland in Punjab, India. Myxospores were consistent with the genus Myxobolus, round to elliptical in valvular view, lemon shaped in side view with a characteristic protrusion at the anterior end and a round posterior end; length 7.65 ± 0.07 μm, width 4.62 ± 0.09 μm. There were two polar capsules of equal length, pear shaped, length of polar capsule 2.54 ± 0.05 μm, width 1.60 ± 0.02 μm, with 5–6 turns of the polar filament. The 890 bp 18S rDNA sequence was up to 97% similar to M. catlae from other cyprinid fishes in India. In having, unique myxospore morphology and 18S rDNA sequence, we propose Myxobolus holzerae as new to science.

Molecular and phylogenetic characterization of Thelohanellus boggoti Qadri, 1962 (Cnidaria, Myxosporea, Bivalvulida) infecting the fin of Indian minor carp Labeo dero (Hamilton, 1822).

A myxozoan parasite belonging to the genus Thelohanellus Kudo, 1933 (Cnidaria, Myxosporea, Bivalvulida) was isolated from the fins of Labeo dero inhabiting Ranjit Sagar Wetland, Punjab, India. The plasmodium was 0.5-0.7 mm in diameter each containing 80- 100 number of myxospores. Myxospores were egg shaped to ovoidal in valvular view having bluntly pointed anterior and broad rounded posterior end measuring 8.36x 4.77 µm. Polar capsule was single, broadly pyriform in shape, measuring 4.77x3.98 µm in size containing a polar filament coiled perpendicular to the longitudinal axis of myxospore body making 7-9 turns. Blast analysis of 18S rDNA sequence of the isolate demonstrated 98% homogeneity with Thelohanellus sp. (KU155561, Unpublished), followed by 91% with T. caudatus (KM252684) and Thelohanellus sp. FCO (KR819273). The intensity of infection was recorded to be light as indicated by fin plasmodial index (FPI = 1). In the present study, T. boggoti has been described using 18S rRNA gene and phylogenetic analysis using MEGA.6.

Life cycle inference and phylogeny of Ortholinea labracis n. sp. (Myxosporea: Ortholineidae), a parasite of the European seabass Dicentrarchus labrax (Teleostei: Moronidae), in a Portuguese fish farm.

Ortholinea labracis n. sp. is described and its life cycle is inferred from a Southern Portuguese fish farm, with basis on microscopic and molecular procedures. This myxosporean parasite infects the urinary bladder of the European seabass Dicentrarchus labrax and the intestinal epithelium of a marine oligochaete of the genus Tectidrilus. Myxospores subspherical in valvular view and ellipsoidal in sutural view measuring 7.6±0.3 (6.8-8.7)μm in length, 7.2±0.2 (6.7-7.7)μm in width and 6.5±0.4 (5.8-7.7)μm in thickness. Two polar capsules, 3.0±0.2 (2.6-3.4)μm long and 2.4±0.1 (2.0-2.9)μm wide, located at the same level, but with divergent orientation and opening to opposite sides of the suture line. Sequencing of the SSU rRNA gene revealed a similarity of 100% between the analysed myxospores and triactinomyxon actinospores. The phylogenetic setting of O.labracis n. sp. shows subgrouping in correlation with tissue tropism, but identifies this parasite as another exception to the main division of Myxosporea into the main freshwater and marine lineages.

Morphological and molecular characterization of Thelohanellus hoffmanni sp. nov. (Myxozoa) infecting goldfish Carassius auratus auratus.

A new species of the genus Thelohanellus Kudo, 1933 (Myxosporea, Bivalvulida) was isolated from the fins of goldfish Carassius auratus auratus (Linnaeus 1758). The fish had been imported from China by an Austrian retailer. Nodules from the margins of the fins contained pyriform myxospores with a singular polar capsule. In valvular view, the spores measured 12.2 µm in length and 6.4 µm in width. In sutural view, the thickness was 2.9 µm. The polar capsule measured 4.2 × 3.1 µm and contained a polar filament with 8 to 9 coils. Histological sections showed plasmodia of 0.2 to 4.0 mm diameter with the earlier developmental stages of the parasite in the periphery and the mature spores closer to the center. In the transmission electron microscope examination, the different developmental stages could be observed. Morphological data, host specificity, tissue tropism, and molecular analysis of the small subunit rDNA identify this parasite as a new species of Thelohanellus, which we have named Thelohanellus hoffmanni sp. nov.