Diagnosis_Species: Perkinsus olseni Lester & Davis 1981. Infected abalone had soft cream or brown necrotic foci 1 to 8 mm across on the surface or within the musculature of the foot and mantle. When near the surface, they appeared as a hemispherical cream or brown swelling. Lesions over 3 mm in diameter contained pus. Those adjacent to the shell caused the formation of a brown scar on the shell’s internal surface.  In fresh smears, spherical cells were 16.6 µm (range of 10 measurements: 14- 18 µm) in diameter with prominent walls. Live cells had a large vacuole up to 10 µm in diameter and 50 to 100 droplets 1 pm in diameter. In fixed tissues, cells 13.8 µm ( 13 - 16 µm) in diameter with peripheral nucleus and a large vacuole were found. A vacuoplast when present was weakly eosinophilic. Dividing cells (19 µm live, 15 µm fixed and stained) divide into two, four, eight or more equal or subequal units.

Body_trophozoite_diameter: 13-16 µm
Body_prezoosporangia_diameter: 56-94 µm