Culture studies of Acrochaete leptochaete comb. nov. and A. wittrockii comb. nov. (Chaetophoraceae, Chlorophyceae)

A culture study of the plants known as Phaeophila leptochaete (Huber) Nielsen and P. wittrockii (Wille) Nielsen proved that these are distinct species. Both have the Acrochaete type of hairs, and therefore, the new combinations Acrochaete leptochaete and A. wittrockii are introduced. Several isolates of both species were started from plants collected at different places in Europe.

A. leptochaete in culture was mainly characterised by having two or more (up to six) pyrenoids in many of its cells, while in A. wittrockii there invariably was only one. The swarmers formed by A. leptochaete had two or four flagella. Several hairs from one basal swelling were sometimes observed in one of the isolates. Another isolate often formed a hair on the germinated zoospore. The isolates of A. wittrockii had a variable morphology, from unicellular plants to large pseudoparenchymatous cell masses. Different kinds of swarmers were observed; zoospores with three flagella seemed typical, but ones with two or four flagella were also observed. Small, pale biflagellate swarmers were assumed to be gametes. One of the isolates of A. wittrockii differed from the rest as the only swarmer type observed was zoospores with two flagella. Chlorophilum ephemerum is considered identical to A. wittrockii. Observations on hair formation in A. repens suggested that the hair structure represents a separate cell.