Lichina confinis (O. F. Müll.) C. Agardh.

    Thallus shrubby, forming loose small cushions on rocks, elongate or circular, to 3-10 cm across and less than 0.5 mm tall, growth pattern in enlarged circles and becoming sparser towards the center to form rings or typically horse-shoe-shaped. Tufts composed of lobes (branches) more or less terete, blackish, dichotomous branching, apices bearing apothecia, globose, pale brown, 1-1.5 mm diam. Ascii (4) 8-spored, 125-145 x 15-30 µm. Ascospores simple, ellipsoid,  12-18 x 10-15 µm according to literature, 15-21 x 10-15 according to our measures. Photobiont: cyanobacteria: Calothrix or Dichothrix. This species preferentially grows above the mean tide level, in the lower section of the orange belt on little exposed rocks (eulittoral zone) and always above Lichina pygmaea. Lichina pygmaea and Lichina confinis are often found in the same sites and the best method to distinguish them without using magnifying lens to observe the branches is to take into consideration their habitat level in relation to the mean tide level. Lichina confinis is usually found with  Caloplaca marina or d'Hydropunctaria (Verrucaria) maura Lichina pygmaea is distributed lower on the foreshore together with barnacles (Balanus). These two lichens, to the contrary of algae, cannot sustain complete and continuous submersion and require exposure to air a few hours a day.