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).

P. longicauda	P. longicauda	P. torta	P. torta var. tortuosa
Phacus sp. big !	P. pleuronectes	P. pleuronectes small var.	P. landekiensis
P. curvicauda	P. caudatus	P. warszewiczii	Phacus sp.
Phacus sp. x 640