SYNOPSIS. A symbiotic alga from the foraminifer Archaias angulatus was isolated axenically. Algae from crushed hosts were coccoid and highly vacuolated; division stages within an envelope were common. Biflagellate motile piriform organisms predominated in newly transferred cultures and were gradually replaced by the coccoid, highly vacuolated stage. Incorporation of 14C label in intact Archaias was greatest for organisms fed and incubated in light. Starved symbiotized organisms incubated in the light incorporated ∼30% as much label as fed counterparts, There was no obvious difference in 45Ca incorporation between fed and starved organisms. Light significantly enhanced calcification. The Archaias symbiont infected Rosalina leei but not Quinqueloculina spp.

No abstract