Verrucaria halizoa forme de l'ombre
This forma is characteristic of the middle zones of the foreshore, not sunny and receiving little light in particular the entry of the sea caves. The thallus is smooth, thin, gelatinous and more or less transparent, greenish at the beginning, it then becomes opacified by becoming brownish (appearance of a thin layer of tar) then blackish with purplish reflections. Thalli 1-3 cm in diameter can form mosaics where they are separated by blackish hypothalline lines. The broadly conical to hemispherical apothecia are rarely deformed (unless in contact with one another) and proliferate centrifugally from the center of the thallus. The photobiont (under study) appears to be different from that of Verrucaria halizoa from the sunnier middle foreshore.