Characterization of four novel actinospore types of fish parasitic myxozoans and the occurrence of and from fish farms of Hungary.

Six distinct actinospore types were identified in the intestinal epithelium of oligochaetes collected from the Szigetbecse and Makád fish farms of Ráckeve Danube Arm Fishing Association, in Hungary. Four new types: triactinomyxon type, raabeia type, aurantiactinomyxon type 1, and aurantiactinomyxon type 2, were described morphologically and molecularly from three invertebrate host species: , and . The 18S ribosomal DNA (rDNA) analysis revealed that these new types of actinospores did not match any myxospore sequences available in GenBank. Phylogenetic analysis placed the triactinomyxon type within the clade that parasitizes cyprinid fish, while the raabeia type and aurantiactinomyxon type 2 were both placed within the clade associated with Perciformes fish. Aurantiactinomyxon type 1 was clustered in a clade containing gill-infecting spp. from Esociformes fish. However, no myxospores have been found yet to link to the newly sequenced actinospores reported in this survey. This study also reports the first occurrence of two oligochaetes species, and in Hungary, specifically in fish farms of Ráckeve Danube Arm Fishing Association. Moreover, this is the first report on the involvement of in the life cycle of myxozoans.