Desmid of the month
July 2009
Penium exiguum
Like P. margaritaceum (desmid of March, 2004) P. exiguum is marked by a finely granulate cell wall. As compared to P. margaritaceum, P. exiguum is smaller in size but more distinctive are the subapical constrictions resulting in capitate cell ends. Girdle bands (which are characteristic of the genus Penium) usually are well to be distinguished. In the Netherlands P. exiguum is occasionally encountered in acidic, oligo-mesotrophic moorland pools. Zygospores, as in other Penium species globose and smooth-walled, are only incidentally found.
Images © Waterdienst RWS (mouse over)
Cell of Penium exiguum marked by capitate apices.
Cell dimensions (L x B): ca 50 x 10 µm
