G lugea sp. infecting Sardinella aurita in Algeria

Parasitological examination of the commercially important pelagic fish Sardinella aurita Valenciennes, 1847 (Clupeidae) from the Eastern coast of Algeria revealed xenomas in the peritoneal cavity, suggesting a microsporidian infection. The prevalence of the disease was approximately 30% on average, higher in smaller individuals and showing significant seasonal variation. The xenomas contained numerous ellipsoidal spores, surrounded by a dense layer of connective tissue. Spore sizes were 6.10 ± 0.38 µm length and 3.54 ± 0.43 µm width. Ultrastructural examination by transmission electron microscopy showed various development stages of the parasite, including meronts, sporonts, sporoblasts and mature spores. The internal organization of the mature spores, with a single nucleus, prominent posterior vacuole, a lamellar polaroplast and an isofilar polar tube arranged in a single row, was typical of the genus Glugea. The DNA sequence of the small subunit ribosomal RNA gene confirmed that this parasite belongs to the genus Glugea. Genetic and morphologic comparison with G. sardinellensis, a species previously described in the same host from Tunisia shows many similarities, although some molecular and morphometric inconsistencies precluded the unambiguous assignment of our samples to G. sardinellensis. At the same time, we do not find sufficient grounds to erect a new taxon for our parasite. We discuss the implications of our findings for the current state of the systematics of Glugea.

from the striated fusilier, Caesio striata, in the Red Sea off Saudi Arabia

Glugea eda n. sp. is described from the mesenteries of the striated fusilier, Caesio striata, collected from the Red Sea coast off Yanbu' al Bahr, Saudi Arabia. Numerous blackish xenomas, ranged from 3 to 5 mm, were found in the body cavity associated with the mesenteries. Mature spores are monomorphic, ellipsoidal with an average size of 5(4-6) μm in length and 2.2 (2-3) μm in width. Observations of the ultrastructure revealed that the development was asynchronous and that the nuclei were isolated throughout the life cycle with uninucleate meronts. Sporoblasts were uninucleated and existed together with sporonts in a fully formed parasitophorous vacuole. The polar filament of the mature spore was isofilar with 24-28 coils, arranged in three rows. Phylogenetic analysis placed the current microsporidia within the clade grouping Glugea species and close to the species described from the Red Sea and Arabian Gulf. The morphometric and molecular comparison with other members of the genus Glugea evidenced the taxonomic novelty of the present form, suggesting that it should be considered as a new species. To the best of our knowledge, the parasite here described represents the first occurrence of microsporidian infection in the fish of the family Caesionidae.