ULTRASTRUCTURAL-STUDY AND DESCRIPTION OF CYSTOSPOROGENES-DELIARADICAEN-SP (MICROSPORA, GLUGEIDAE), A MICROSPORIDIAN PARASITE OF THE CABBAGE ROOT FLY DELIA-RADICUM (LINNAEUS, 1758) (DIPTERA, ANTHOMYIDAE)

The microsporidium Cystosporogenes deliaradicae sp. nov., a parasite o f the adipose tissue of adult cabbage root flies, Delia radicum in Den mark, is described based on light microscopic and ultrastructural char acteristics. All life cycle stages have isolated nuclei. The sporogony is polysporoblastic, yielding 4-16 (most commonly 6 or 8) ovocylindri cal spores, measuring 1.2-1.5 x 4.6-5.5 mu m when fixed and stained. T he spore wall has an approximately 43 nm thick, layered exospore with a median layer resembling a double membrane. The polaraplast is unifor mly lamellar. The isofilar, 114-123 nm thick, polar filament is arrang ed in 11-15 (most commonly 12-13) coils in a single layer close to the spore wall. The angle of tilt is approximately 35 degrees. The last c oil touches the posterior pole of the spore. A sporophorous vesicle is produced by the sporont. The envelope is generated as a duplication o f the plasma membrane. Typically the vesicle primordia grow from one p ole of the sporont to the other. The episporontal space initially has granular inclusions. Later septate, persistent tubules of exospore mat erial appear. Simultaneously with the release of sporoblasts, wide tub ulus-like, non-persistent structures are formed. They are covered by r egularly spaced electron-dense material. anomalous sporogony was frequ ently observed, probably caused by a simultaneous parasitism by the fu ngus Strongwellsea castrans. The systematic position of the microspori dium is discussed, including the reasons for incorporating the genus i nto the family Glugeidae.