Development of Schroedera plumatellae gen. n., sp n. (Microsporidia) in Plumatella fungosa (Bryozoa: Phylactolaemata)

A new microsporidian, Schroedera plumatellae, is described infecting a freshwater bryozoan. The development of the infection is described both at the light and ultrastructural level. The infection induces the formation of hyperplastic testes within the bryozoan host from which cord-like xenomas form. Development of diplokaryotic sporonts is preceded by haplophasic schizogony. Sporogony forms diplokaryotic spores. The spores formed within the xenomas are oval, tapering to one end and were 7.2 +/- 0.3 mum by 5.0 +/- 0.3 mum with 22-23 turns of the polar filament. Sporogony occurred within the hyaloplasm with the exospore developing into two distinct layers. Phylogenetic analysis showed that the parasite was most closely related to a Bacillidium sp. and Janacekia debaisieuxi.