Myxobolus cultus n. sp. (Myxosporea: Myxobolidae) in the goldfish Carassius auratus transformed from the actinosporean stage in the oligochaete Branchiura sowerbyi.

A new myxosporean Myxobolus cultus n. sp. was found in experimentally infected goldfish Carassius auratus exposed to actinosporean spores from the oligochaete Branchiura sowerbyi (Tubificidae). At 2-4 mo following initial exposure, spores of M. cultus were observed in the cartilage of goldfish. A lymphocytic infiltrate surrounded the pseudocysts. Some pseudocysts were destroyed and spores had been engulfed by phagocytes. Phagocytized spores were also found in the epidermis of skin and within melanomacrophage centers in the kidney.