Cosmarium denboeri in apical view
Image © Alfred van Geest

Cell of Cosmarium denboeri in apical view. Notice strong, median inflation of the semicell.

Cosmarium denboeri
Image © Alfred van Geest

Cell of Cosmarium denboeri in frontal view. Notice oblong semicells with slightly produced apex.

Cell dimensions (L x B): 20 x 20 µm

 

 

Desmid of the month
February 2016

Cosmarium denboeri

C. denboeri is a small-sized, inconspicuous Cosmarium species. Cells are about as long as broad with a deep sinus that usually opens about halfway. Semicells are elliptic-oblong in outline, the apex usually slightly produced. The centre of the semicell is abruptly inflated and furnished with a group of small granules. At the semicell margin and just within it also a series of distant, acute granules/dentations. C. denboeri (named after our webmaster, Kees den Boer) was only recently described*, but in the Netherlands it appears to be widely distributed in plankton of eutrophic, alkaline water bodies.

* Meesters, J. & Coesel, P.F.M., 2007. Cosmarium denboeri: een nieuwe, planktonische sieralgsoort met een potentieel groot verspreidingsgebied. Gorteria 32: 144-147.

Cosmarium denboeri, empty cellImage © Alexander Klink

Dead cell of Cosmarium denboeri well showing produced apices and dentate margins.

Cosmarium denboeri, SEM image Image Ton Joosten © Waterdienst, Lelystad

SEM picture of Cosmarium denboeri showing cell wall sculpturing in detail.