Picture taken at Garraf Park Information Center, on a brick wall, South exposure, vertical, 300 m. altitude.
Common lichen on calcareous rocks and walls.
Crustose lichen, very variable, areolate, thick, with a very typical white marginal area of the thallus and with not a very conspicuous dark prothallus.Apothecia present, with a black disc, with pruina , 1 mm diameter.
It is very variable. It is necessary to compare with existing Rinodina species, very similar in form. I remind you a very good paper on Rinodina with keys:
M. Giralt, X. Llimona (1997) The saxicolous species of the genera Rinodina and Rinodiella lacking spot test reactions in the Iberian Peninsula. Mycotaxon, Vol. LXII, pp. 175-224.
Realment, en tot el mon vegetal costa identificar espècies que són molt variables i que poden induïr a confussions, i que unes bones claus d'identificació són fonamentals.
Molt bona la captura i molt interessant l'explicació.