The thesis deals with localization and quantification of Sphaerospora molnari (Myxozoa) in common carp (Cyprinus carpio). Sphaerospora molnari is microscopic endoparasite which attacks various tissues and organs, preferentially parasitizing intracellularly (histozoic type) in a carp fry. In this work, we studied the course of parasite infection in the various tissues and organs of the host (blood, gills, skin, kidney, liver, and muscle) in laboratory conditions. The course of infection was detected using qPCR.

The Malacosporea and Sphaerospora sesnsu stricto clade are the two most basal myxozoan clades. While the evolutionary older malacosporeans possess unique features resembling cnidarians, sphaerosporids are known for special developmental features and unique long insertions in the small and large subunits of the ribosomal DNA. This thesis aimed at elucidating the hidden biodiversity, describing special biological traits and tracing the evolutionary history of these two clades based on both, morphological and molecular data. Host-parasite phylogenetic congruence was studied to understand the evolutionary patterns of cospeciation and host switching.