Desmid of the month
June 2013

Gonatozygon kinahanii

Gonatozygon kinahanii. Notice elongate, cylindric cell holding two plate-like chloroplasts.

Cell dimensions (L x B): 420 x 15 µm

Gonatozygon kinahanii very much resembles G. monotaenium except that its cell wall is perfectly smooth instead of finely granulate. By this, it can be easily confused with loose cells of the filamentous zygnematalean genus Mougeotia. Both taxa are characterized by elongate, cylindric cells provided with  plate-like chloroplasts. However, whereas cells in Mougeotia hold but a single chloroplast, those in Gonatozygon usually have two of them (one per semicell). In addition to that, cells of Gonatozygon kinahanii may be recognized by their pinched apical angles (versus more rounded in Mougeotia). Like in G. monotaenium, cells of G. kinahanii may stick together to form filaments of variable length. G. kinahanii has a wide ecological range: from mesotrophic to slightly eutrophic and from slightly acidic to alkaline. In the Netherlands it is rather widely distributed (but often overlooked).

Another cell of G. kinahanii. Notice pinched apical angles.

Cell of G. kinahanii amongst several chlorococcalean algae, a euglenid (and a cell of Cosmarium humile) indicating an eutrophic environment (actually, a garden pond).

Detail of the same cell showing an unsculptured, smooth wall characteristic of G. kinahanii.

Detail of the same cell in another position showing that the chloroplast is really plate-like (not pillar-shaped).

Cell of G. kinahanii with, below, some loose cells of the filamentous alga Mougeotia.

Filament of 3 cells
Image © Jan Šťastný

Filament of 3 cells of G. kinahanii.