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The present study records the presence of Bipteria lusitanica n. sp. in wild white seabream, Diplodus sargus (Linnaeus, 1758) off the Portuguese coast. Myxosporean parasites were found in the interstitial tissue of kidney and free in urinary bladder of D. sargus with a 33.3% of prevalence of infection. Myxospores were triangular or inversely pyramidal in shape and anteriorly wider in frontal view, measuring 11.2 ± 1.0 μm in length, 12.6 ± 0.9 μm in width, and 11.6 ± 0.4 μm in thickness. The sinuous sutural line was parallel to the axis that connects the center of the two polar capsules. Spore valves were smooth without ridges. Wing-like appendages extended from the posterior part of each valve in sutural view, measuring 3.9 ± 1.1 μm in length. Spherical polar capsules measured 4.4 ± 0.2 μm in diameter and the polar filaments were helical arranged in 5-6 turns. Molecular data showed that this parasite clusters within species of the Sinuolineidae Shulman, 1959 family, and they all infect the urinary bladder. Using molecular and morphological characterization, we were able to identify this parasite as a novel species of the genus Bipteria Kovaleva, Zubtchenko, and Krasin, 1983. [ABSTRACT FROM AUTHOR]

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 85.0–94.0 μm long and 70.0–82.0 μm 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. [ABSTRACT FROM AUTHOR]

Chloromyxum squali Gleeson and Adlard, 2012 originally described from Squalus acanthias Linnaeus, 1758 is reported for the first time from the gallbladder of Squalus blainville (Risso, 1827) caught from the eastern coast of Tunisia. In the present study, this chloromyxid was described based on morphological and ultrastructural features combined with molecular analysis of 18S rDNA. Young plasmodia were found attached to the gallbladder, while mature plasmodia and myxospores were observed floating free in the bile. Mature plasmodia were polysporic, subspherical in shape, measured 97.8 ± 0.5 µm long and 63.4 ± 0.4 µm wide. Mature myxospores were ovoid with a pointed anterior end, measuring 10.2 ± 0.5 µm long and 8.3 ± 0.5 µm wide. Two asymmetrical shell valves adhered together along an S-shaped suture line. Each valve has 5–7 elevated surface ridges parallel to suture line. A bundle of long caudal filaments extended from the basal end of shell valves. Four pyriform polar capsules equal in size, measuring 3.1 ± 0.4 µm long and 2.5 ± 0.3 µm wide, were situated at the same level in the anterior pole of the myxospore, each with a polar filament coiled in 7–8 turns. Pairwise comparisons among the SSU rDNA sequences revealed significant similarity between Chloromyxum squali infecting S. acanthias with the sequence obtained in this study. Phylogenetic analysis revealed that C. squali clustered in the clade of Chloromyxum species infecting the gallbladder of marine Chondrichthyes. Chloromyxum squali showed a seasonal variation of prevalence with significantly higher prevalence noted in summer and in autumn and absence of infection in winter. [ABSTRACT FROM AUTHOR]

Ceratomyxa gouletti n. sp. is a new parasite described from the gallbladder of the red scorpionfish Scorpaena scrofa (Scorpaeniformes: Scorpaenidae) collected from La Goulette in the Northeast of Tunisia. The parasite develops disporic plasmodia, elliptical to ovoid in shape, measuring up to 33.1 ± 3.6 (28.0-38.2) μm in length and 12.5 ± 2.1 (11.3-14.0) μm in width. Mature spores are elongated transversely and crescent-shaped with rounded ends and unequal shell valves, measuring 8.1 ± 1.27 (7.2-9.0) μm in length and 32.0 ± 2.5 (27.0-38.2) μm in thickness. Sutural line is straight and visible between valves. Polar capsules are subspherical with 3.15 ± 0.63 (2.7-3.6) μm long and 1.9 ± 0.14 (1.8-2.0) μm wide. Posterior spore angle is slightly concave 160°-175°. Molecular analysis based on the small subunit 18S rDNA sequence shows that C. gouletti n. sp. is different from all other ceratomyxid species DNA sequences in GenBank. Phylogenetic trees clustered the new species with long-branching Ceratomyxa species, and it was closely related to the species Ceratomyxa longipes from two gadid fish hosts with 89% bootstrap support. [ABSTRACT FROM AUTHOR]

Infections with myxozoan parasites are a source of concern for fish farm owners, as they can lead to significant economic losses. Owing to such potential detrimental impact, a comprehensive body of knowledge on myxozoans is required and, in this regard, elucidating different aspects of their ecology at the micro- and macroenvironment-level scales is crucial. The present study addresses the correlates of infections at both level-scales, for species of myxozoans occurring in Dicentrarchus labrax (Teleostei: Moronidae), an economically important species of fish for the aquaculture industry. Infection data for Sphaerospora dicentrarchi and S . testicularis (Myxozoa: Sphaerosporidae), and Ceratomyxa diplodae and C . labracis (Myxozoa: Ceratomyxidae), obtained from a total of 764 fish from wild ( N = 373) and cultured ( N = 391) environments, were used in the analyses. The mean prevalences of infection were 79.8% for S . dicentrarchi , 6.2% for S . testicularis and 21.7% for Ceratomyxa spp. At the microenvironment-level scale, a significant relationship was detected between the host sex, age, total weight and length and the prevalences of infection. At the macroenvironment-level scale, the prevalence of S . dicentrarchi was higher in wild than in cultured fish, contrary to that observed for Ceratomyxa spp. The results obtained from the Generalized Linear Model analysis suggest that, the control of the environmental variables which influence the occurrence of infection constitutes a crucial prophilatic measure in the minimization of economic losses occurring in fish farming systems. [ABSTRACT FROM AUTHOR]