Dirina ceratoniae (Ach.) Fr.

     Thallus crustose relatively thick, 1-3 mm thick, with wavy thickenings in places, rarely cracked, greyish-white if dry, pale yellowish, pale greenish-yellow if moist, hypothalle whitish dirty to darker than thallus. Apothecia always numerous and at different stages of growth, often grouped together in the center of the thallus, sessile, 1-3 mm in diameter, disc greyish to blackish but appearing whitish under a very large bloom, thalline rim thick, smooth, wavy in contact with other apothecia, concolorous with thallus. Hyaline spores, elongated, more or less curved (banana), 3-septate, 21-26 x 4-5.5 µm depending on the literature; 22-25 x (4) 5-6 µm according to our measurements. Photobiont: Trentepohlia. Cortex and apothecia: C+ red, KC+ fleeting red; medulla: C-, K-, KC-, P-. Mediterranean thermophilic species coming on the bark of trees usually in the vicinity of the sea.

NB. DNA studies have shown that this species could also be saxicolous (on limestone rocks) but that there were no morphological or microscopic characters allowing to differentiate it from Dirina massiliensis forma massiliensis reliably, however the latter species is C+ pink according to our observations.