Vegetative cell of Actinotaenium diplosporum (forma maius) displaying asteroid chloroplasts.

Cell dimensions (L x B): ca 105 x 50 µm

 

 

Desmid of the month
November 2006

Actinotaenium diplosporum

A. diplosporum is notable because of its very wide and shallow sinus rendering the cell a somewhat guitar-shaped outline. In addition to that, cells are characterized by asteroid chloroplasts whereas conjugation results in the formation of twin zygospores. In the Netherlands A. diplosporum is only known from a few mesotrophic moorland pools.

Conjugated cells of A. diplosporum with twin zygospore.

Vegetative cell of A. diplosporum (forma maius) showing chloroplast configuration in more detail.

Twin zygospore of Actinotaenium diplosporum forma maius

Twin zygospore of A. diplosporum (forma maius) showing four pyrenoids in each spore: two of them (the sharply marked ones) originating from the 'older' gametangial semicells, the other two originating from the (hardly developed) young semicells formed just before conjugation (compare process of conjugation in Closterium ehrenbergii on our web page 'The process of sexual reproduction'). Notice also (faintly expressed) scattered cell wall pores in empty gametangial semicells.