Staurodesmus extensus Image © Henk Schulp

Staurodesmus extensus. Note the elongate isthmus and the obversely trapeziform semicells.

Cell dimensions (L x B): ca 30 x 35 µm (including spines).

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Year
Additions

Desmid of the month
March 2007

Staurodesmus extensus

Staurodesmus extensus is characterized by biradiate cells with an elongate isthmus. Semicells are rectangular to obversely trapeziform in outline and the apical angles are furnished with a spine. Length and projection of the spines are most variable (giving rise to the distinction of quite a series of varieties). In the Netherlands, Std. extensus is one of the most common Staurodesmus species to be encountered in acidic habitats. Sexual stages (zygospores) can be met with occasionally.

Another specimen of Std. extensus, marked by relatively long spines (cf var. joshuae).

Zygospore of Std. extensus with adhering, empty gametangial cells. The globose spore is furnished with solid spines gradually broadening towards their base.

Desmid of the month March 2007

Staurodesmus extensus

Desmid of the month
March 2007