A New Microsporidium, Nosema cristatellae n. sp. in the Bryozoan Cristatella mucedo (Bryozoa, Phylactolaemata)

A microsporidian infecting cells of the body wall of the phylactolaemate bryozoan Cristatella mucedo is described. All stages of the parasite are diplokaryotic and lie in direct contact with the host cell cytoplasm. Sporogony is probably disporoblastic. Spores measure 7.5 x 5.1 &mgr;m and have 22-32 coils of the polar tube arranged in several rows and a bell-like polaroplast of compact membranes. The parasite is assigned to the genus Nosema as a new species, Nosema cristatellae. It is differentiated from the previously described parasites of Alcyonella (=Plumatella) fungosa (Bryozoa), named Myxosporidium bryozoides and Nosema bryozoides, by spore characters and tissue specificity. Although it was found in a different species of bryozoan, it is not known whether N. cristatellae is infective to P. fungosa. Copyright 1997 Academic Press. Copyright 1997 Academic Press