Classification and definition of cytokinetic patterns in green algae: Sporulation versus (vegetative) cell division

Abstract

Summary In this paper a preliminary survey and classification are given of cytokinetic events in the green algae. Two basic patterns can be distinguished depending on the kind of cells produced: if daughter cells are motile or evidently derived from a motile (flagellated) condition, the preceding division event is to be considered as “Sporulation”. If there are no (ultra)structural signs of daughter cells being flagellated, they are considered to have originated by “Zellteilung” (vegetative cell division). This concept is essentially based on a proposal made by Ettl in 1988 with the following modifications. First, the genesis and the nature of the division product (i.e., whether or not it is a [possibly reduced] flagellated cell) has been selected as the main distinguishing criterion. The additional criterion of Ettl 's concept concerning the question whether or not a given division event is associated with growth or with reproduction is abandoned. This results in a more transparent and internally more consistent classification. Secondly, definition of cytokinetic categories is less ambiguous if ultrastructural characters are taken into account. A survey is given of the occurrence of these redefined division patterns among major groups of green algae.