Thallus: crustose, effuse, smooth to slightly verrucose, 0.3-0.7 mm diam. surface: creamy brown to green-brown; soredia: not seen cortex: 20-40 µm thick medulla: white, chalky Ascomata: numerous, circular in outline, sessile, 0.8-1.2 mm diam.; exciple: entire or slightly undulating, protruding above the disc; epithecium, light brown to brown, 25-60 thick; hymenium: hyaline asci: clavate, 70-110 µm, 8-spored ascospores: fusiform, curved, smooth, 3-septate, hyaline, 25-31 x 4-5 µm Spot tests: thallus: K+ yellow turning red, C-, KC-, P+ yellow-red Secondary metabolites: an unknown substance. Substrate and ecology: growing on bark of trunks, twigs and branches of different trees and shrubs near the ocean World and Sonoran distribution: Roccellina conformis is found only from a few sporadic localities near the sea from Santa Catalina Island, California, down to Laguna Manuela in southern Baja California. Notes: Roccellina conformis is similar to Dirina paradoxa subsp. approximata which also grows on the trunks and branches of various trees and shrubs near the sea. Roccellina conformis is easily distinguished from the latter by its C- thallus reaction. Roccellina franciscana differs in its K- and P- reaction and in the more pruinose, grayish white thallus and much more undulating, nearly stromatoid, subimmersed ascocarps with an unconstricted base.