Genus: Highly flattened; pellicle firm; body form constant (Kudo, 1966).
Chloroplasts small, discoid, pyrenoids usually absent; most species flat and leaf-shaped;
often with ridges or fins running helically or longitudinally (Illustrated Guide, 1985).
50 μm
100 μm
150 μm; x 400 :
31 μm
63 μm
94 μm; x 640
Phacus longicauda, x 400, x 640, Uruguay Nov. 1999, photo by Yuuji Tsukii
