Cosmarium regnellii. Notice semicells that are more or less hexagonal in outline with broadly rounded angles and retuse sides interconnecting the lateral angles with the apical and basal ones.

Cell dimensions (L x B):  17 x 15 µm

Another cell of C. regnellii in wjich the hexagonal shape of the semicells is more pronounced.



Desmid of the month
August 2020

Cosmarium regnellii

C. regnellii is a small-sized, smooth-walled Cosmarium species. Among the many varieties that have been described there are several ones that may be confused with similarly looking species. The nominate variety is characterized by cells that are a bit longer than broad. Semicells are somewhat hexagonal in outline with rounded angles and (slightly) retuse lateral margins. In the Netherlands, C. regenellii is common in various habitats including alkaline, eutrophic pools.

SEM picture of C regnellii. Notice that the cell wall is scrobiculate in nature.

Image Hanny Kooijman née Van Blokland © IBED

SEM picture of C. regnellii showing scattered pores among the closely spaced scrobiculae.