The first finding of myxosporean development from plasmodia to spores in terrestrial mammals:: Soricimyxum fegati gen. et sp n. (Myxozoa) from Sorex araneus (Soricomorpha)

Soricimyxum fegati gen. et sp. n. is a new myxosporean (Myxozoa) species discovered in the liver of shrews, Sorex araneus L., collected in the Bialowieza primeval forest (Poland). Both developmental stages and mature spores were found during a histological study. The infection had about 40% prevalence at the investigated locality. Plasmodia were polysporic. Elongated plasmodia with an average size of 30 by 8 mu m occupied bile ducts and larger rounded plasmodia up to 80 mu m in diameter were found in liver parenchyma where they most probably entered after the ducts had been destructed. Plasmodia in both locations elicited a vigorous inflammatory reaction. Spores were of an ovoid shape, 7 mu m long, 5.4 mu m wide and about 3.5 mu m thick. They had two shell valves and two equal polar capsules, located in opposite ends of the spore.