PKX organism is identified as a new species of the myxozoan genus Tetracaps
ula, for which the name Tetracapsula bryosalmonae n.sp. is proposed. It inf
ects several species of phylactolaemate bryozoans and salmonid fish. It is
differentiated from the type species Tetracapsula bryozoides in that spores
are derived by aggregation of cells rather than by division of a single sp
orogonic cell, by minor morphological features and by its 18S rDNA sequence
.