Structure of Labyrinthula sp. Zoospores*

Abstract

SYNOPSIS. A species of Labyrinthula closely resembling L. algeriensis was isolated from marsh grass, Spartina alterniflora. Zoosporulation was obtained in ∼50% of the cultures, which were grown on a modified Vishniac medium, when yeasts were used as food organisms; when the temperature was ∼22 C; when thiamine (0.2 mg/l, biotin (1 μg/l, Ba (1 μg/l, and cholesterol (5 mg/l) were present; and when the cells were grown on a semisolid medium (0.6% agar) rather than higher concentrations of agar. The motile cells were similar to biflagellated fungal zoospores in that they were pyriform and laterally biflagellated. The anterior flagellum (13‐15 μ long) possessed what appeared to be 2 rows of mastigonemes and was uniform in diameter while the posterior flagellum (6‐10 μ) lacked mastigonemes and was tapered distally into a whiplash. The planonts are apparently not isogametes since planogametic copulation could not be induced and since synaptinemal complexes were not observed in sectioned presporangia.