Xanthidium tenuissimum. Notice small cell dimensions, spines at the lateral angles and shallow, widely open, obtusely angled sinus.
Cell dimensions (L x B): 8 x 10 µm



Desmid of the month
August 2019

Xanthidium tenuissimum

X. tenuissimum is a very small-sized Xanthidium species (in older floras usually to be found under the genus of Arthrodesmus). Cells are about as long as broad with a rather shallow, obtusely angled sinus. Semicells are more or less hexagonal with a short, rather blunt spine at each of the lateral angles. The apex is broadly truncate to strongly concave. Close to each of the apical angles there is an additional minute spine but those are pointed to the observer and often overlooked. In the Netherlands, X. tenuissimum was encountered rather recently for the first time and up to now only known from a number of acidic, oligotrophic sites in the province of Drenthe.

Empty cell of X. tenuissimum in frontal view. Notice indication of minute, subapical spines.

Empty semicell of X. tenuissimum in apical view showing the four subapical spines.

Image © Marien van Westen

SEM picture of X. tenuissimum even better exhibiting the subapical spines.