Saprolegnia parasitica

Animal / pathogen
colony of Saprolegnia parasitica infects epidermis of Salmonidae

Animal / pathogen
colony of Saprolegnia parasitica infects epidermis of Salmo trutta

Saprolegnia parasitica Coker, Saproleg. 57. 1923
Isoachlya parasitica Nagai, Jour. Fac. Agr. Hokkaido Univ. 32: 12. 1931.
Growth rather delicate on usual media, moderately dense, not long, rarely reaching 1 cm. on a mushroom-grub; gemmae abundant, very variable in size and shape, often in chains, mostly terminating hyphae, sometimes intercalary; sporangia variable, usually bent and irregular, at times up to 0.7 mm. long, very often proliferating from below as in Achlya, when growing through others sometimes discharging spores through the side wall of the old sporangium; spores 9-11.5 ju thick; oogonia usually formed only on special media, spheric, subspheric, pyriform, or clavate, 65-95 /j. in diameter, borne on the tips of the hyphae or intercalary, the wall thin, smooth, and unpitted; eggs 18-22 /i in diameter, subcentric, 3-25 in an oogonium; antheridial branches long, slender, diclinous or androgynous; antheridia clavate or subcylindric, usually 1-5 to an oogonium, rarely lacking.
Type locality: Wytheville, Virginia. Habitat: Parasitic on fish. Distribution: Cosmopolitan.