Sphaerozosma aubertianum
Image © Koos Meesters

Filament of Sphaerozosma aubertianum. Notice ellipsoid semicells, on their lateral sides marked by granule-like mucous extrusions.
Cell dimensions (L x B): ca 20 x 20 µm

 

 

Desmid of the month
March 2014

Sphaerozosma aubertianum

Sphaerozosma aubertianum very much resembles Sph. vertebratum. Differences between those two species are subtle and, maybe, partly questionable (Coesel & Van Westen 2013). Sph. aubertianum is said to differ from Sph. vertebratum by more pronounced cell wall pores, marked by granule-like gelatinous extrusions. Moreover, semicell shape is elliptic rather than rounded-oblong, resulting in a wider opened cell sinus. Whereas the globose zygospore in Sph. aubertianum is furnished with long spines, that in Sph. vertebratum (only recorded in a few nineteenth century publications) is described as smooth-walled. In the Netherlands, Sph. aubertianum is a rare species, recently encountered in some mesotrophic moorland pools.

Reference:
Coesel, P.F.M. & Van Westen, M.C., 2013. Taxonomic notes on Dutch desmids V (Streptophyta, Desmidiales): new species, new morphological features. — Phytotaxa 84: 46-54.

Sphaerozosma aubertianum, almost empty cells, cell wall poresImage © Koos Meesters

Filament of Sph. aubertianum with (almost) empty cells. Notice transversal rows of cell wall pores: two in each semicell.


 

Sphaerozosma aubertianum, mucilaginous shaethImage © Koos Meesters

Sph. aubertianum fotographed with interference contrast showing a filament that is surrounded by a thick mucilaginous sheath.

SEM image © Marien van Westen

Cell of Sph. aubertianum, SEM image.

Sphaerozosma aubertianum, interconnecting apicall cell processes
Image © Koos Meesters

Filament of Sph. aubertianum in lateral view better showing the interconnecting apical cell processes.

Sphaerozosma aubertianum, spiny zygospore
Image © Marien van Westen

Spiny zygospore of Sph. aubertianum.

SEM image © Marien van Westen

Zygospore of Sph. aubertianum, SEM image.