engleski

Occurence of the pathogen Psorospermium haeckeli in Astacid populations in Croatia

Psorospermium haeckeli is a thick-walled unicelular organism widely reported in European astacid crayfish. Its taxonomic status has recently being elucidated, it is closely related to the similar organisms of aquatic pathobiology and they all consist DRIP clade which is near the animal-fungal divergence. Psorospermium haeckeli is considered as a &laquo ; ; ; parasite&raquo ; ; ; although its pathogenic impact still remaines unclear. Untill now there were no data about its presence in Croatian astacid crayfish. We examined 119 specimens of the three astacid species from 10 different locations and found sporocysts of the Psorospermium haeckeli in 7 preparations of epidermal-connective tissue of Astacus astacus and A. leptodactylus. Preparations were made by scraping the epidermal-connective tissue from under the carapace, treating it with 10% KOH and viewing it under the microscope at 120 x magnification. Relative scale was used to describe the degree of infection of the crayfish by P. haeckeli. We found only the mature form of Psorospermium haeckeli. The sporocyst was quite long and narrow and was sourounded by three layers: innermost membranous layer ; the cell wall which is well formed, thick and consists of numerous plates and, barely visible, but fully developed outermost gelatinous layer. Psorospermium sporocyst contained a few large globules and many small ones or sometimes was filled with only small uniform globules. In the A. leptodactylus we found many sporocysts which were fully melanised. Further investigations are needed to understand distribution of infected crayfish in Croatia and patterns of their infection with Psorospermium.

Psorospermium haeckeli; Astacidae; Croatia

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