Desmid of the month
September 2003

Spondylosium ellipticum

Spondylosium belongs to the group of colonial, filamentous desmid genera. Contrary to the genera Hyalotheca and Desmidium, dealt with earlier in this series, intercellular connections are delicate, so readily to be broken. Therefore, in practice, often only rather small fragments (consisting of up to some five or ten cells) will be encountered, rather than long, twisted filaments. Single cells of Spondylosium much resemble small, smooth-walled Cosmarium cells. Most probably, mutual relationship of these two genera is much closer than between Spondylosium and most of the other filamentous desmid genera.

The herewith pictured species, identified as Spondylosium ellipticum *, until recently was unknown for the Netherlands. A few years ago it was encountered in a slightly acid, mesotrophic moorland pool near the village of Oisterwijk. Also outside of the Netherlands it has been recorded only incidentally.

 

* Identification is under some reservation as in Wests’ flora (vol. 5, p. 222) the absence of a mucous sheath is explicitly stated whereas in our material such a sheath is demonstratively present.