The life history of Pyramimonas amylifera Conrad (Prasinophyceae)

Several possible life history stages of a clone of Pyramimonasamylifera Conrad (Prasinophyceae) have been encountered in culturestudies. These include: 1) octoflagellates; 2) cysts; 3) quadriflagellates;4) biflagellates; and 5) multilobate cells with each lobe bearingeight flagella. The octoflagellates have the ultra-structuralcharacteristics previously documented for P. amylifera. Scanningelectron microscopy was used to examine surfaces of cysts andbiflagellates. Scales of the type which form the middle (basket-shaped)and outer (coronate) scale layers on the octoflagellate wereobserved on the surface of cysts. Scales of the type which formthe middle body layer on octoflagellates were observed on thebodies of biflagellates. Biflagellates, quadriflagellates, andempty cysts were observed in several cultures which had beensubjected to a 5-week dark incubation before return to a low-lightregime. In one of those cultures, a single cyst containing motileswarmers was observed. The biflagellates or quadriflagellatesmay represent cyst-germination products. ^*Present address: Department of Biology, University of SouthFlorida, Tampa, Florida, U.S.A. 33620.