Actinosporean diversity in a Hungarian fish farm and description of the life cycle of Zschokkella chezhachei

Six distinct actinospore types were identified in the intestinal epithelium of three oligochaete species collected from a fish farm in Ócsárd, in Hungary. Among these, two new types: aurantiactinomyxon type 1 and aurantiactinomyxon type 2 were described both morphologically and molecularly from <i>Branchiura sowerbyi</i>. Other actinospores detected in <i>B. sowerbyi</i>, <i>Tubifex tubifex</i> and <i>Limnodrilus hoffmeisteri</i> have been known previously in literature. Three myxosporean life cycles were inferred through molecular analysis, including a newly described one. Analysis of 18S ribosomal DNA (rDNA) revealed that aurantiactinomyxon type 2 matched the sequence of <i>Zschokkella chezhachei</i> from the bile duct of gibel carp available in GenBank, hereby inferring its life cycle. Phylogenetic analysis placed the aurantiactinomyxon type 1 within the <i>Thelohanellus</i> clade that parasitizes gibel carp and common carp. In contrast, aurantiactinomyxon type 3 and raabeia type 2 clustered within the <i>Myxobolus</i> clade associated with perciform and centrarchid fishes. Additionally, neoactinomyxon type 1 grouped with <i>Thelohanellus wangi</i>, a parasite of gill filaments in gibel carp, while raabeia type 1 clustered with <i>Myxobolus cultus</i>, found in the gill filaments of gibel carp and gold fish. This study represents the first report of the actinospore stage of <i>T. wangi</i> in Hungary, and the second report of the actinospore stage of <i>M. cultus</i>.