DEVELOPMENT OF THELOHANELLUS-HOVORKAI AND THELOHANELLUS-NIKOLSKII (MYXOSPOREA, MYXOZOA) IN OLIGOCHAETE ALTERNATE HOSTS

The development of Thelohanellus hovorkai, a myxosporean parasite of t he connective tissues, and Thelohanellus nikolskii, a fin and scale pa rasite of common carp (Cyprinus carpio) was studied in experimentally infected oligochaetes Branchiura sowerbyi and Tubifex tubifex, respect ively. After infection with mature spores of T. hovorkai, the developm ent of actinosporean stages was first observed light microscopically i n the gut of Branchiura sowerbyi 93 days after infection. Free actinos pores of T. hovorkai were found in the lumen of the oligochaete's gut 101 days after infection. They were floating in water and showed a typ ical aurantiactinomyxon form. At 18-22 degrees C, aurantiactinomyxon s pores of T. hovorkai emerged from the worms 104 days after infection. The development of T. nikolskii was examined in Tubifex tubifex, from which aurantiactinomyxon spores were released 60 days after infection at 22-24 degrees C. The diameter of spore body was 18.6 mu m and the l enght of caudal processes 29 mu m for T. hovorkai, while 21.1 mu m and 13.4 mu m for T. nikolskii, respectively. The prevalence of aurantiac tinomyxon infection in B. sowerbyi for T. hovorkai proved to be 16.7%, while in T. tubifex for T. nikolskii it was 12.5%.