Dolichospermum

The genus Dolichospermum is divided in two groups:
Dolichospermum with coiled trichomes – PVIK – open version.
Trichomes clearly coiled, regularly or irregularly.

Dolichospermum with straight trichomes – PVIK – subscription.
Trichomes straight, sometimes slightly bent, but not really spiral.

In Dolichospermum species the akinete is a very important feature in identifying. That is why this feature was chosen to the key, although you can’t always see any akinetes. The length of the akinete is filled under the graphic, on the left side – Measured length. Normally this place is for the length of the cell, but with heteocytous cyanobateria you measure the akinete.

Well, if you can’t see any akinetes? You can still use the width of the vegetative cell and all the filters. You just fill in the width of the cell on the right side, under the graphic, and choose the filters that are suitable. PVIK will help you anyway to narrow down the possible species of that width.

When you have the akinete too – bingo! You get even a nicer short list of candidates.

Literature used for the key:
Komárek, Jirí . 2013. Cyanoprokaryota, Teil 3: Heterocytous Genera. Süßwasserflora von Mitteleuropa, Band. 19. Springer Spectrum, 1130 p.