DEVELOPMENT OF MYXOBOLUS-HUNGARICUS (MYXOSPOREA, MYXOBOLIDAE) IN OLIGOCHAETE ALTERNATE HOSTS

The extrapiscine development of Myxobolus hungaricus Jaczo, 1940, a my xosporean parasite of the gill of bream Abramis brama, was studied in experimentally infected oligochaetes Tubifex tubifex and Limnodrilus h offmeisteri. Uninfected tubificids were infected with mature spores of M. hungaricus, and development of actinosporean stages was first obse rved by light microscopy 21 d later. In histological sections, early p ansporocysts were located in the gut epithelium of the experimental ol igochaetes. Mature pansporocysts, each containing 8 triactinospores, a ppeared 89 d after infection. After rupture of the epithelial cell and the pansporocyst, free actinosporean stages were found in the gut lum en of the oligochaete. Actinospores emerged from the oligochaetes and appeared in water 102 d after infection. They were floating in water a nd showed a typical triactinomyxon form. Each triactinospore had 3 pyr iform polar capsules, a sporoplasm with 18 secondary cells inside the spore body, a moderately long style and 3 slightly bent, conically end ing tails. The total length of the triactinospore was approximately 31 5 mu m. The prevalence of infection in 67 oligochaetes proved to be 43 .3%. No infection was found in control oligochaetes.