Collemopsidium foveolatum forme sur Patella
Form found on Patella. Currently under investigation. This form is very variable, the thallus can be endolithic or be in relief and edged by a whitish "prothallus-like" or, especially in the case of mosaic, limited by a "scar" rim. The perithecia, very small, are on well-characterized individuals, buried in a cavity of the thallus but there are individuals whose medium-sized perithecia are a little emerging and in this case it may be very difficult to distinguish them from Collemopsidium sublitorale which this species shares several common characteristics.
See: Evolution and taxonomy of the marine Collemopsidium species (lichenized Ascomycota) in north-west Europe. MORH Fiona, EKMAN Stefan, HEEGAARD Einar. Mycol. Res. 108 (5) : 515-532 (May 2004). The British Mycological Society.*