Occurrence of Myxobolus spp. (Myxozoa) in the blood of Metynnis lippincottianus (Osteichthyes: Serrasalmidae) from eastern Amazon, Brazil.

Myxozoans are obligatory parasites and can be found in various organs and bloodstreams of fish, thus, the objective of this work was to describe the occurrence of Myxobolus spp. in the circulating blood of Metynnis lippincottianus from River Curiaú, Macapá City, eastern Amazon, Brazil. The samples of M. lippincottianus (11) were caught using cast net and gillnets. The fish blood was collected by puncturing the caudal vessel, using needles and syringes containing 10% of EDTA solution. Blood smear were prepared and panchromatic stained with a combination of May Grunwald-Giemsa-Wright, for observation and examination of the parasitic structures in optical microscope. Tissues from the kidney was examined using specific stereoscopic binoculars to check for the presence of cysts, lesions and parasites. The prevalence of Myxobolus spp. infecting the circulating blood of the fish was 36.36% (4/11) and 15 spores of mixosporyds were visualized. Myxobolus spp. had a prevalence of 54.55% (6/11) in host's kidney tissue and the morphometric spores data converge with observed in the blood. The morphological characteristics of the spores in the blood samples revealed two morphotypes of Myxobolus spp. This is the sixth occurrence recorded of Myxobolus spp. infecting fish blood in Brazil.

A NEW SPECIES OF MYXOBOLUS (CNIDARIA: MYXOSPOREA: MYXOBOLIDAE) FROM THE BLUE SUCKER, CYCLEPTUS ELONGATUS (LESUEUR) (CYPRINIFORMES: CATOSTOMIDAE: CYCLEPTINAE), FROM ARKANSAS.

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

Myxobolus sp. (Myxozoa; Myxosporea) causing asymptomatic parasitic gill disease in Astyanax aff. bimaculatus (Characiformes; Characidae) in the Tocantins river basin, amazon region, Brazil / Myxobolus sp. (Myxozoa; Myxosporea) causando doença parasitária assintomática nas brânquias em Astyanax aff. bimaculatus (Characiformes; Characidae) na bacia do rio Tocantins, região amazônica, Brasil

Abstract The middle course of the Tocantins river is located in the eastern portion of the "Legal Amazon" region of Brazil and the Dantas river is one of its tributaries. Among the components of the aquatic biota, eukaryote microparasites establish direct relationships with several species of fish and have zoonotic potential that is still little known. Myxozoans stand out among these parasites: they cause myxosporidiosis, a disease that gives rise to high mortality rates worldwide. The genus Myxobolus accounts for the largest number of species that have been described. Thirty specimens of Astyanax aff. bimaculatus that had been caught in the Dantas river were examined. The prevalence of cysts with spores morphologically compatible with myxozoans of the genus Myxobolus in the arcuate and gill filaments of these specimens was 20%.

Resumo O curso médio do rio Tocantins está localizado na porção leste da região da "Amazônia Legal" do Brasil, e o rio Dantas é um dos seus afluentes. Dentre os componentes da biota aquática, os microparasitos eucarióticos estabelecem relações diretas com várias espécies de peixes e possuem potencial zoonótico ainda pouco conhecido. Os mixozoários destacam-se entre esses parasitos causando mixosporidiose, doença que dá origem a altas taxas de mortalidade em todo o mundo. O gênero Myxobolus é responsável pelo maior número de espécies descritas de mixozoários. Trinta espécimes de Astyanax aff. bimaculatus capturados no rio Dantas foram examinados. A prevalência de cistos com esporos morfologicamente compatíveis com mixozoários do gênero Myxobolus nos filamentos arqueados e branquiais desses espécimes foi de 20%.

Myxobolus sp. (Myxozoa; Myxosporea) causing asymptomatic parasitic gill disease in Astyanax aff. bimaculatus (Characiformes; Characidae) in the Tocantins river basin, amazon region, Brazil.

The middle course of the Tocantins river is located in the eastern portion of the "Legal Amazon" region of Brazil and the Dantas river is one of its tributaries. Among the components of the aquatic biota, eukaryote microparasites establish direct relationships with several species of fish and have zoonotic potential that is still little known. Myxozoans stand out among these parasites: they cause myxosporidiosis, a disease that gives rise to high mortality rates worldwide. The genus Myxobolus accounts for the largest number of species that have been described. Thirty specimens of Astyanax aff. bimaculatus that had been caught in the Dantas river were examined. The prevalence of cysts with spores morphologically compatible with myxozoans of the genus Myxobolus in the arcuate and gill filaments of these specimens was 20%.

Morphological and molecular characterization of Myxobolus dibombensis sp. n. (Myxozoa: Myxobolidae), a parasite of the African carp Labeobarbus batesii (Teleostei: Cyprinidae) from Dibombe River, Cameroon.

Myxobolus dibombensis sp. n. (Cnidaria: Myxosporea: Bivalvulida) is described from the fins of the African carp, Labeobarbus batesii, based on morphological and molecular data. Prevalence of infection was 51.9% (67/129). Ovoid to spherical cyst-like plasmodia were found in the intrasegmental region and among the fin rays. No pathological changes were found in the fish host tissue surrounding the cyst-like plasmodia. Mature myxospores were ovoid in frontal view and lenticular in lateral view, with slightly truncated anterior and rounded posterior ends. Myxospores measured 16.8 (15.8-18.0) µm long and 11.4 (10.0-13.0) µm wide. There was a triangular intercapsular appendix measuring 3.8 (2.6-4.5) µm long. Polar capsules were ovoid and slightly unequal in size, occupying approximately one-third of the myxospore length. The larger polar capsule measured 7 (6-8) µm long and 3.6 (3-4) µm wide, while the smaller one measured 5.8 (4.8-7.0) µm long and 3 (2-4) µm wide. The larger polar capsule contained nine to 11 filament coils, whereas the smaller one contained seven to nine coils. SSU rDNA gene sequence of M. dibombensis sp. n. did not match any sequences available in the GenBank. The similarity with available Myxobolus spp. sequences ranged from 65 to 81%. The novel species clustered with M. algonquinensis, which infects the cyprinid Luxilus cornutus from Canada.

Supplemental diagnosis and phylogeny of Myxobolus absonus (Cnidaria, Myxozoa) from the eye of the freshwater fish Pimelodus maculatus (Siluriformes, Pimelodidae).

Myxobolus absonusCellere et al., 2002 was originally described as having free cysts in the opercular cavity of the freshwater fish Pimelodus maculatus in Brazil. The present study provides a supplemental description of this parasite from the eye of its type host, with basis on morphological, ultrastructural, and molecular data of the SSU rRNA gene. The parasite formed spherical whitish cysts, which wall presented numerous microvilli that attached to the collagen layers of the corneal stroma. Myxospores were oval in valvular and sutural view, measuring 13.2 ± 0.4 µm in length, 8.5 ± 0.4 µm in width, and 6.6 ± 0.3 µm in thickness. Two asymmetric pyriform polar capsules were located at the anterior pole: the larger 6.2 ± 0.4 µm long and 3.6 ± 0.3 µm wide, containing a polar filament coiled in 6 turns; and the smaller 3.5 ± 0.3 µm long and 1.9 ± 0.1 µm wide, containing a polar filament coiled in 4 turns. At the posterior pole, the sporoplasm displayed two nuclei and numerous spherical sporoplasmosomes. Phylogenetic analysis using maximum likelihood, Bayesian inference and maximum parsimony revealed M. absonus clustering within a well-supported clade with poorly-resolved internal nodes, amongst the SSU rRNA sequences of other myxobolids that infect siluriform and characiform fish hosts, as well as the perciform-infecting species Myxobolus acanthogobii, Triangula percae and Cardimyxobolus japonensis. This clade appeared separated from the other clades comprising most of the species that infect siluriform and characiform hosts, showing that more than one myxobolid lineage evolved while parasitizing these taxonomic groups of fish.

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.

Morphological and molecular characterization of a novel myxosporean parasite Myxobolus bejeranoi n. sp. (Cnidaria: Myxosporea) from hybrid tilapia in Israel.

Myxosporean infections can cause severe damage to commercially grown tilapia. Here, we report a novel myxosporean that was found in gills of Oreochromis aureus male × Oreochromis niloticus female, which is an important aquaculture tilapia hybrid in Israel. Three-month-old fish were found to have cysts located in gill muscle tissue, which were filled with both immature and mature spores. Affected fish displayed higher mortality rate. Spore dimensions (10.8 ± 0.7 µm length × 6.8 ± 0.6 µm width) and molecular characterization using 18S ribosomal DNA revealed that the unknown parasite belongs in the Myxobolus clade. Based on the infection site, spore morphology and molecular characterization, we describe this parasite as Myxobolus bejeranoi n. sp. (MF401455). Phylogenetic analysis showed that the new species is most closely related to two Myxobolus spp. from O. niloticus in Egypt and Ghana.

Myxobolus marajoensis sp. n. (Myxosporea: Myxobolidae), parasite of the freshwater catfish Rhamdia quelen from the Brazilian Amazon region / Myxobolus marajoensis sp. n. (Myxosporea: Myxobolidae), parasita do bagre de água doce Rhamdia quelen da região da Amazônia brasileira

Abstract This study provides morphological and molecular data of a new parasite species found in the muscle layer of the intestinal tract of the South American silver catfish, Rhamdia quelen from Marajó Island region (Pará State, Brazil), an important fishery resource with recognized potential for fish farming. The morphology of these parasites was reanalyzed and phylogenetic analyses were run on their 18S rDNA gene sequences. The spores were morphologically distinct from those of other Myxobolus species described previously. The obtained partial sequence of the 18S rDNA gene sequences of the new species were compared to those of 24 other Myxobolus and Henneguya species available in GenBank. The results of morphological and molecular analyses indicated clearly the existence of a new species, Myxobolus marajoensis sp. n.

Resumo Este estudo fornece dados morfológicos e moleculares de um novo parasita encontrado na parede intestinal do jandiá, Rhamdia quelen coletado na região da ilha do Marajó (Estado do Pará, Brasil), um importante recurso pesqueiro com potencial para aquicultura. Foram realizadas comparações morfológicas deste parasita e análises filogenéticas da região do gene 18S rDNA sequenciada. Os esporos foram morfologicamente distintos das espécies de outros Myxobolus descritos anteriormente. A sequência parcial obtida do gene 18S rDNA da nova espécie foi comparada com outras 24 espécies de Myxobolus e Henneguya retiradas do GenBank. Os resultados de análises morfológica e molecular indicaram claramente a existência de uma nova espécie, Myxobolus marajoensis sp. n.

Morphological and molecular characterization of Myxobolus sheyangensis n. sp. (Myxosporea: Myxobolidae) with intralamellar sporulation in allogynogenetic gibel carp, Carassius auratus gibelio (Bloch) in China.

Allogynogenetic gibel carp is one of the most important freshwater cultured species in China. However, myxosporidiosis represents a severe threat to prevent the sustainable development of aquaculture of this species. During the investigation of myxosporean diversity of reared allogynogenetic gibel carp in East China, a new myxosporean with typical characteristics of Myxobolus was found from 169 out of 210 (80.4 %) examined samples, designated as Myxobolus sheyangensis n. sp. by combing comparative analysis of morphological and molecular data. The diagnostic features of this species are reminiscent with Myxobolus pyramidis Chen, 1958 as follows: round or ellipsoidal, grayish white, cyst-like polysporous plasmodia, averaging 219.3 ± 11.9 (98.7-421.7) × 158.4 ± 9.7 µm (79.9-191.8) in size; spores flat-pear shaped in frontal view with tapering anterior and rounded posterior ends and lemon-shaped in sutural view, averaging 11.0 ± 0.31 (10.5-11.9) × 10.2 ± 0.25 (9.2-10.7) × 6.3 ± 0.23 µm (5.9-6.9) in size; and two equal pyriform polar capsules averaging 5.5 ± 0.3 (4.5-6.1) × 3.4 ± 0.26 µm (2.9-4.0) in size with convergent longitudinal axes and polar filaments wounded in seven to eight coils, perpendicularly to the longitudinal axis of the polar capsules. Spore surface was smooth and two spore valves were symmetrical, with a thin and straight sutural ridge. Occasionally, abnormal spores with typical Henneguya-like caudal appendage and atypical papillary caudal appendage could be observed. The sporogenesis is asynchronous. Histopathological investigation showed that the plasmodia developed inside the capillary network of gill lamellae, belonging to the intralamellar vascular type, and no significant inflammatory responses were provoked by the infection. Homology search by BLAST showed that the newly obtained sequence did not match any available sequences in GenBank. Phylogenetic analysis of the aligned sequences indicated that M. sheyangensis n. sp. positioned in a clade composed of Myxobolus species infecting the gill of several freshwater cyprinid fish.

Molecular characterization and morphological aspects of Myxobolus parvus (Myxozoa) from Liza saliens (Mugilidae) off the Turkish Black Sea coasts.

Members of the phylum Myxozoa are among the most cosmopolitan parasites of fish, and the genus Myxobolus is the largest within the class Myxosporea in freshwater and marine environment from all over the world. Myxobolus parvus has been reported from mainly mugilid fishes from different localities including the Black Sea. Leaping mullet Liza saliens collected by fishermen off Sinop coasts of the Black Sea in the period between September 2014 and December 2015 was investigated for myxosporean parasites using conventional methods. M. parvus Schulman, 1962 was the only Myxobolus species identified and it was found in the gills, gall bladder, kidney tubules, and inside several cysts located on the lower jaw of examined fish in the present study. Morphometric data and all details of parasitic infection were determined and presented in tables and illustrated in figures. Molecular characterization was also conducted to reveal its position within Myxosporea. Two M. parvus samples from gills and kidney showed the same haplotype and appeared in the same sub-lineage with marine Myxobolus species. The closest haplotypes to M. parvus were Triactinomyxon sp. and Endocapsa sp. which are the actinosporeans forms of unknown myxozoan species. These data are the first in molecular characterization of M. parvus, its occurrence in lower jaw of leaping mullet along with its infection prevalence values off the Turkish Black Sea coasts.

Myxozoan infections of the three Indian major carps in fish ponds around Meerut, UP, India, with descriptions of three new species, Myxobolus basuhaldari sp. n., M. kalavatiae sp. n. and M. meerutensis sp. n., and the redescription of M. catlae and M. bhadrensis.

New myxosporean species are described from Indian fishes cultured in pond farms of Meerut, Uttar Pradesh (UP) state. Based upon plasmodia found in the Indian major carps (Catla catla, Cirrhinus cirrhosus, Labeo rohita and their hybrids), three new Myxobolus spp., Myxobolus basuhaldari sp. n., Myxobolus kalavatiae sp. n. and Myxobolus meerutensis sp. n., are described, and two species, Myxobolus catlae and Myxobolus bhadrensis, are redescribed. Plasmodia of M. basuhaldari sp. n., M. kalavatiae sp. n., M. meerutensis sp. n. and M. catlae developed in small cysts in the gill lamellae, while plasmodia and scattered spores of M. bhadrensis were found in the muscles and kidney, respectively. Plasmodia and spores found in these fishes differed from each other with respect to their morphology, tissue tropism and 18S ribosomal DNA (18S rDNA) sequence. No major pathological changes were found, but severe infections were observed.

Study of Myxosporea (Myxozoa), infecting worldwide mullets with description of a new species.

Existing data on Myxozoa parasites infecting mullets were reviewed. The validity of nine species names was updated. Sixteen species were registered during analysis of original material collected in the Mediterranean, Black, Azov, and Japan Seas in 2004-2005. A new bivalvulid myxozoan parasite, Myxobolus adeli n. sp., was described from the inner organs of the golden grey mullet Liza aurata (Risso, 1810) collected in the Mediterranean (Ebro Delta, Spain), Black Sea (Kerch Strait, Ukraine), and Azov Sea (Genichesk, Ukraine) coastal waters. It is characterized by the presence of elongated, spindle-like cysts 0.5-1.3 mm in size, filled with wide transverse-oval spores about 6.2 × 7.2 × 4.6 µm in size, with two equal polar capsules measuring about 3.0 × 1.8 µm and short polar filament, turned into four coils. The obtained data show that this species differs from all previously described Myxobolus spp. with equal polar capsules. Comparative study of Myxobolus spp. recorded in worldwide mullets indicates a close relationship with M. adeli n. sp. and Myxobolus improvisus Isjumova, 1964 registered in mullets. Probably, the last species includes representatives of some different species, infecting freshwater and marine hosts.

Myxobolus anatolicus sp. nov. (Myxozoa) infecting the gill of Anatolian khramulya Capoeta tinca (Cyprinidae) in Turkey.

This work is part of an ongoing investigation into the characteristics of myxozoan parasites of freshwater fish in Turkey and was carried out using morphology, histopathology and molecular analysis. A new species of the genus Myxobolus (M. anatolicus sp. nov.) was found infecting the gills of 3 of 34 specimens (8.8%) of Anatolian khramulya Capoeta tinca from the Samsun Province, Northern Turkey. Both morphology and 18S rDNA sequence data revealed that M. anatolicus sp. nov. was distinct from other Myxobolus species found in the gills of cyprinid fishes. The small, white and round-shaped plasmodia, measuring 0.2 to 1.4 mm in diameter, were observed macroscopically in the gills. Histological analysis revealed that the cyst-like plasmodia have an intralamellar-vascular type development. Mature spores of M. anatolicus sp. nov. were oval in both frontal and sutural views, and tapered at the anterior poles. The spores were 10.1 ± 0.41 (9.4 to 10.7) µm long, 6.9 ± 0.28 (6.6 to 7.2) µm wide, and 4.5 ± 0.36 (4.4 to 4.6) µm thick. The 2 polar capsules were pyriform, equal in size, 4.6 ± 0.45 (4.4 to 4.8) µm long and 2.1 ± 0.12 (2 to 2.3) µm wide. Polar filaments within the polar capsules were coiled with 5 or 6 turns. Phylogenetic analysis placed M. anatolicus sp. nov. in a clade of gill-infecting myxobolids. This is the first record of a Myxobolus species infecting Anatolian khramulya Capoeta tinca, and the first record of this species from Eurasia.

Two novel myxosporean species (Myxosporea: Bivalvulida), Myxobolus marumotoi n. sp. and Cardimyxobolus japonensis n. sp., from the dark sleeper, Odontobutis obscura, in Japan.

Two new myxosporean species, Myxobolus marumotoi n. sp. and Cardimyxobolus japonensis n. sp. (Myxozoa: Myxosporea: Bivalvulida), are described from the dark sleeper, Odontobutis obscura, in Japan, based on their morphological and molecular characterizations. Plasmodia of M. marumotoi n. sp. (Myxobolidae) grew in the myofiber of trunk muscles, forming pseudocysts. The rounded spore was relatively large, measuring 13.3-15.0 µm (average 13.8) in length, 14.2-15.0 µm (14.6) in width, and 10.0-11.7 µm (10.8) in thickness, with two subspherical polar capsules of 7.9-9.6 µm (8.4) in length by 5.4-6.3 µm (5.9) in width (n = 15). The polar capsules were directed toward the apex of the spore, packing five to six spirals of the polar filament. Plasmodia of C. japonensis n. sp. (Ortholineidae) were surrounded by thin fibrous tissue, forming cysts in the lamina propria of the alimentary tract. The spore was ovoid, wider than long, in valvular view and spindle-shaped in sutural view. It measured 8.8-10.4 µm (9.4) in length, 11.3-12.5 µm (11.9) in width, and 5.2-6.7 µm (5.8) in thickness, with two ovoid polar capsules of 4.2-5.0 µm (4.7) in length by 2.9-3.8 µm (3.3) in width (n = 15). The shell valves of spores often showed a flattened anterior border and semicircular posterior border, and the two polar capsules were directed toward opposite lateral sides. In addition, the sporoplasm contained an iodinophilous vacuole. Almost complete small-subunit (SSU) rDNA sequences, except for primer flanking regions, were obtained for both species; 1,996 bp long for the former and 1,588 bp long for the latter. On phylogenetic trees based on the SSU rDNA sequences of representative species of Bivalvulida, M. marumotoi n. sp. and C. japonensis n. sp. formed a distinct branch in the Henneguya/Myxobolus clade or near but outside this clade, respectively. This study is the first report of the genetic characterization for the genus Cardimyxobolus.

Proliferation and resistance difference of a liver-parasitized myxosporean in two different gynogenetic clones of gibel carp.

Some myxosporeans have been demonstrated to be harmful to worldwide aquaculture. However, the proliferation information has remained unclear in the fish hosts. In this study, we utilized the mix-culturing equality to reveal significant difference in disease assistance between two different clones of gibel carp, in which clone D had been cultured for nearly 40 years, whereas clone A(+) was a newly created clone. According to morphological and genetic analysis of isolated spores, the diseasing pathogen was identified as Myxobolus wulii of the genus Myxobolus in Myxosporea. Subsequently, a polyclonal antibody specific to soluble proteins of the purified spores was generated. Using the antibody, we performed immunofluorescence observation of the liver lump sections sampled from the heavily diseased clone D individuals, and found that the liver lumps were completely composed of numerous honeycomb-like cysts, full of maturing and mature myxosporean spores, and almost all of liver tissues were destroyed. Comparative co-localization detection revealed a significantly inducing expression of apo-14 protein around the infected myxosporean sporoplasms and plasmodia, and the inducing level was much stronger in clone A(+) than in clone D. Furthermore, a primarily screening of 15 different major histocompatibility complex class Iα variants also excavated major variants that respectively belong to clones D and A(+). Therefore, these data provide significant information for differences in myxosporean proliferation and disease resistance in fish clone hosts with different genetic background. Further studies on myxosporean development and the mechanism for disease resistance will be very important for preventing and controlling the parasitic myxosporean disease.

Phylogeny, ultrastructure and histopathology of Myxobolus lomi sp. nov., a parasite of Prochilodus lineatus (Valenciennes, 1836) (Characiformes: Prochilodontidae) from the Peixes River, São Paulo State, Brazil.

This paper presents the morphological, histological, molecular and ultrastructural data on Myxobolus lomi sp. nov., a parasite of the gill filaments of Prochilodus lineatus from the Peixes River (48º06'38″W; 22º 49'53.1″S), São Paulo State, Brazil. From 20 P. lineatus specimens examined, 90.0% (n=18) were infected. The plasmodia were white and round, measuring 250 to 300µm in diameter and the development occurred in the base of the gill filament. The spores showed symmetrical and smooth valves, with the polar filament having 8 to 11 coils. A thorough comparison with all the Myxobolus species described so far is provided. A partial sequencing of the 18S rDNA gene revealed approximately 1600-bp. The Myxobolus species parasite of P. lineatus did not match any of the Myxozoa available in GenBank. In the phylogenetic analysis, M. lomi sp. nov. is clustered with ten other species and only four of these parasites were from gills. Histological analysis of P. lineatus gills infected by M. lomi sp. nov. revealed numerous well-delimited cysts at the base of the primary lamella, between connective tissue and bone, next to the gill arteries. However no pronounced inflammatory response was found at the infection site.

Morphologic and genetic evidence for mixed infection with two Myxobolus species (Myxozoa: Myxobolidae) in gray mullets, Mugil cephalus, from Korean waters.

The present study was performed to trace the decisive evidence for mixed infection of 2 Myxobolus species, M. episquamalis and Myxobolus sp., in the gray mullet, Mugil cephalus, from Korean waters. Mullets with whitish cyst-like plasmodia on their scales were collected near a sewage plant in Yeosu, southern part of Korea, in 2009. The cysts were mainly located on scales and also found in the intestine. The spores from scales were oval in a frontal view, tapering anteriorly to a blunt apex, and measured 7.2 µm (5.8-8.0) in length and 5.3 µm (4.7-6.1) in width. Two polar capsules were pyriform and extended over the anterior half of the spore, measuring 3.5 µm (2.3-4.8) in length and 2.0 µm (1.5-2.2) in width. In contrast, the spores from the intestine were ellipsoidal, 10.4 µm (9.0-11.9) in length and 8.4 µm (7.3-10.1) in width. The polar capsules were pyriform but did not extend over the anterior half of the spore, 3.7 µm (2.5-4.5) in length and 2.2 µm (1.8-2.9) in width. The nucleotide sequences of the 18S rDNA gene of the 2 myxosporean spores from scales and intestine showed 88.1% identity to each other and 100% identity with M. episquamalis and 94.5% identity with M. spinacurvatura from mullet, respectively. By the above findings, it is first confirmed that mullets from the Korean water are infected with 2 myxosporean species, M. episquamalis and Myxobolus sp.

Myxobolus leafa sp. nov. (Myxozoa: Bivalbulida) from the gill filament of Labeo bata (Hamilton) from Manipur, India.

OBJECTIVE: The aim of this study was to investigate the gill filaments of Labeo bata in India parasitologically and to describe the new Myxozoa parasite species, Myxobolus leafa sp. nov., which was determined. METHODS: Fish were collected alive from fish farms from Manipur (India). Sporogonic plasmodia were removed with sterile forceps and observed under phase contrast microscope. For permanent preparations, air dried smears were stained with Giemsa after fixation in acetone free absolute methanol. RESULTS: Mature spores of the new species appear as leaf-like structures in valvular or frontal view, tapering at both ends. The anterior end of the spore is broader than the posterior end. Spores measure 15.3-11.8 µm (16.91 ± 1.16) in length and 13.6-15.3 µm (14.15 ± 0.67) in breadth. CONCLUSION: The new gill parasite species, Myxobolus leafa sp. nov., was described from fish in India. The prevalence of the parasite was 3.3% and two stages (cyst and spore) of the parasite existed in its life cycle.

Infection of wild mullet (Mugil cephalus) with Myxobolus episquamalis in Korea.

Wild mullet (Mugil cephalus) with white cysts on their scales were obtained from Yeosu on the south coast of Korea in 2009. Cyst-like plasmodia consisted of a large number of mature myxosporean spores and numerous sporogonic stages. Spores were oval-shaped in their front view, tapering anteriorly to a blunt apex, and lenticular in their lateral view. They measured 7.0 µm (6.2-7.6) in length, 5.2 µm (4.0-6.2) in width, and 4.9 µm (3.8-6.0) in thickness. Polar capsules contained a polar filament with five to six turns and measured 3.5 µm (2.5-4.5) in length and 2.0 µm (1.6-2.3) in width. Nucleotide sequences of the 18S rRNA gene of the myxosporean parasites in our study showed 99.8 % identity with Myxobolus episquamalis Egusa, Maeno and Sorimachi, 1990 from mullet in Tunisia. These results suggest that the Myxobolus sp. found on the scales of wild mullet is M. episquamalis. In the histopathological examination, spores were observed not only in the plasmodia on the scales, but also in the intestine, pancreas, heart, kidney, stomach, gill, skin, spleen, and liver, suggesting the possibility of the coinfection by different Myxobolus species.