Two different morphotypes could be distinguished:
colonies with irregularly spiralled trichomes which were determined as A. flos-aquae
(Lyngbye) Brébisson ex Bornet et Flahault (Fig. 3), and regularly coiled trichomes (Fig. 4).
The latter trichomes often accumulated to very dense coiled rope-like colonies and were
determined as A. discoidea (Schmidle) Ostenfeld (Fig. 5, 6). The shape and size of the
vegetative cells (spherical to slightly oval, 5 x 5-7 µm) and heterocysts (spherical, 6-8 µm in
diameter) in both taxa were identical (Figs 7, 8). Akinetes were not observed.