Cosmarium rostafinskii
image © Alfred van Geest


Cosmarium rostafinskii. Notice trapeziform semicells with some 16 marginal crenations.
Cell dimensions (L x B): 46 x 31 µm


Your Pic
image © Alfred van Geest

Empty cell of Cosmarium rostafinskii. Notice shallow sinus and transversal band of supraisthmial granules (mouse-over).

 


Desmid of the Month
June 2025

Cosmarium rostafinskii*


C. rostafinskii belongs to a group of Cosmaria the cells of which are marked by elongate trapeziform, crenulate semicells, a relatively shallow sinus and more or less well developed longitudinal series of granules just above the isthmus. Ecologically, they can be linked to shallow, often ephemeral pools and rain puddles. In C. rostafinskii, the longitudinal series of granules are well developed forming a broad, transversal band over the inflated semicell base. In the Netherlands, C. rostafinskii is only incidentally recognized and possibly not seldom confused with other species.

* Also known as C. speciosum var. rostafinskii (Gutw.) West et G.S.West


Cosmarium rostafinskii
image © Alfred van Geest

Isthmial view of C. rostafinskii showing basal inflation of semicell.

Cosmarium rostafinskii
image © Alfred van Geest

SEM picture of C. rostafinskii showing cell wall ornamentation in detail.