Saprolegnia longicaulis sp. nov. is described from litter (floating twigs,
leaves, and roots) in Vitel Sur Stream, in Buenos Aires Province, Argentina
. The species is illustrated and compared with other species of the genus.
It differs from S. australis in having very long oogonial stalks, mature oo
spores, and in lacking androgynous antheridial branches; the zoosporangia a
re very much longer; the oogonia and the oospores are larger.