New and known taxa ofChlorella (Chlorophyceae): Occurrence as lichen phycobionts and observations on living dictyosomes

The algal partner of the lichenPseudocyphellaria carpoloma is a newChlorella species,Chl. sphaerica. It has a saucer- or band-shaped parietal to subparietal chloroplast with a spherical pyrenoid surrounded by a shell of starch. In some of the fully grown cells two dictyosomes lying parallel to each other and changing their position can be observed in the living state. Reproduction occurs by up to 16 autospores. 8 otherPseudocyphellaria species are also lichenized withChlorella phycobionts, apparently belonging toChl. sphaerica.The phycobiont ofWoessia fusarioides belongs toChlorella saccharophila var.ellipsoidea, and to a strain which is morphologically almost identical to one formerly isolated from the lichenTrapelia coarctata. Its ability to gather granules of india ink on the surface of young cells is one of the remarkable characters differentiating it from the latter. In the lichen thallus its cells are regularly penetrated by fungal haustoria.