Glugea pimephales Fantham, Porter, and Richardson, 1941, n comb (Microporidia: Glugeidae) in the fathead minnow, Pimephales promelas

A microsporidan parasite, fitting the description of Nosema pimephales Fantham, Porter and Richardson, 1941, was found in fry of the fathead minnow, Pimephales promelas Rafinesque, from the Wray Fish Hatchery near Fort Morgan, Colorado. More detailed studies proved it to be a typical species of Glugea Thélohan, 1891, to which genus it was transferred. Presence of a delicate sporophorous vesicle, like that recently demonstrated in the type species, was observed. A sequence of three distinct kinds of divisions within that membrane, beginning with the plasmodium and ending with sporoblasts, was recognized. These were plasmotomy, multiple fission, and binary fission. The first two kinds, under the one name or the other, have been treated as one process in previous studies on species of Glugea. Results of this, a well as of recent studies, compel us to reconsider our concepts of "sporont" and "sporogony."