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 constitute DRIP clade which is near the animal-fungal divergence. P. haeckeli is considered as a &laquo ; ; ; ; parasite&raquo ; ; ; ; although its pathogenic impact still remains unclear. Untill now there were no data about its presence in Croatian Astacid crayfish. We examined 144 specimens of the three Astacid species from 12 different locations and found sporocysts of the P. haeckeli in 13 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 125x, 250x and 400x magnification. Relative scale was used to describe the degree of infection of the crayfish by P. haeckeli. We found two types of mature sporocysts and also some developing stages of P. haeckeli. Both types of sporocysts were sourounded by three layers: innermost double membraned layer ; the cell wall which is well formed, thick and amorphous ; outermost layer which consists of numerous plates. Psorospermium sporocysts contained a few large globules and many small ones or sometimes were 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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